diff --git "a/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" "b/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" --- "a/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" +++ "b/raw_rss_feeds/https___arxiv_org_rss_astro_ph.xml" @@ -7,3574 +7,1837 @@ http://www.rssboard.org/rss-specification en-us - Wed, 21 Jan 2026 05:00:28 +0000 + Fri, 23 Jan 2026 05:00:11 +0000 rss-help@arxiv.org - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 Saturday Sunday - Orbital Stability of Closely-Spaced Four-planet Systems - https://arxiv.org/abs/2601.11692 - arXiv:2601.11692v1 Announce Type: new -Abstract: We investigate the orbital dynamics of four-planet systems consisting of Earth-mass planets on initially-circular, coplanar orbits around a star of one solar mass. In our simulations, the innermost planet's semimajor axis is set at 1 AU, with subsequent semimajor axes spaced equally in terms of planets' mutual Hill radii. Several sets of initial planetary longitudes are investigated, with integrations continuing for up to $10^{10}$ orbits of the innermost planet, stopping if a pair of planets pass within 0.01 AU of each other or if a planet is ejected from the system. We find that the simulated lifetimes of four-planet systems follow the general trend of increasing exponentially with planetary spacing, as seen by previous studies of closely-spaced planets. Four-planet system lifetimes are intermediate between those of three- and five-planet systems and more similar to the latter. Moreover, as with five-planet systems, but in marked contrast to the three-planet case, no initial semimajor axes spacings are found to yield systems that survive several orders of magnitude longer than other similar spacings. First- and second-order mean-motion resonances (MMRs) between planets correlate with reductions in system lifetimes. Additionally, we find that third-order MMRs between planets on neighboring orbits also have a substantial, though smaller, destabilizing effect on systems very near resonance that otherwise would be very long-lived. Local extrema of system lifetimes as a function of planetary spacing occur at slightly smaller initial orbital separation for systems with planets initially at conjunction relative to those in which the planets begin on widely-separated longitudes. This shift is produced by the asymmetric mutual planetary perturbations as the planets separate in longitude from the initial aligned configuration that cause orbits to spread out in semimajor axis. - oai:arXiv.org:2601.11692v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + OmniSpectra: A Unified Foundation Model for Native Resolution Astronomical Spectra + https://arxiv.org/abs/2601.15351 + arXiv:2601.15351v1 Announce Type: new +Abstract: We present OmniSpectra, the first native-resolution foundation model for astronomy spectra. Unlike traditional models, which are limited to fixed-length input sizes or configurations, OmniSpectra handles spectra of any length at their original size, without resampling or interpolation. Despite the large-scale spectroscopic data from diverse surveys fueling the rapid growth of astronomy, existing foundation models are limited to a fixed wavelength range and specific instruments. OmniSpectra is the first foundation model to learn simultaneously from multiple real-world spectra surveys with different configurations at a large scale. We achieve this by designing a novel architecture with adaptive patching across variable lengths, sinusoidal global wavelength encoding, local positional embeddings through depthwise convolution, and validity-aware self-attention masks. Allowing us to learn multi-scale spatial patterns while skipping attention for invalid patches. Even with a limited training example, OmniSpectra demonstrates excellent zero-shot generalization compared to methods tailored for specific tasks. This transfer learning capability makes this model the state-of-the-art across various astronomy tasks, including source classification, redshift estimation, and properties prediction for stars and galaxies. OmniSpectra reduces the need for training individual models for different tasks from scratch, establishing itself as the next-generation astronomy foundation model. + oai:arXiv.org:2601.15351v1 + astro-ph.IM + cs.AI + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Bennet Outland, Gretchen Noble, Andrew W. Smith, Jack J. Lissauer + Md Khairul Islam, Judy Fox - Exoplanet atmospheres and demographics in the 2040s - https://arxiv.org/abs/2601.11695 - arXiv:2601.11695v1 Announce Type: new -Abstract: Direct observations of exoplanets probe the demographics and atmospheric composition of young self-luminous companions, yielding insight into their formation and early evolution history. In the near future, Gaia will reveal hundreds of nearby young exoplanets amenable to direct follow-up observations. Long-baseline interferometry with current and future facilities is best capable of exploiting this unique synergy which is poised to deliver a statistical sample of benchmark planets with precise dynamical masses and in-depth atmospheric characterization. This will enable tackling the longstanding question of how giant planets form from multiple angles simultaneously, shining light on the complex physical processes underlying planet formation. - oai:arXiv.org:2601.11695v1 + LISA and the LISA Science Team + https://arxiv.org/abs/2601.15365 + arXiv:2601.15365v1 Announce Type: new +Abstract: LISA, the Laser Interferometer Space Antenna, due to launch mid-2035, is a large class space mission by the European Space Agency (ESA). In partnership with NASA and ESA-member states, ESA is on track to launch what is expected to be the first space-based gravitational wave detector. By hosting detectors in space, one gains access to a lower frequency band of gravitational wave sources and with them, a plethora of new science. To maximise this scientific gain, ESA and NASA selected 20 scientists for the LISA Science Team, to carry out and/or lead necessary actions on the run up to LISA launch. We give a short overview and update of the LISA mission, some of its science objectives and related waveforms, as well as the work of the LISA Science Team as of December 2025. + oai:arXiv.org:2601.15365v1 astro-ph.IM - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jens Kammerer, Sydney Vach, Sylvestre Lacour, Mathias Nowak, Thomas Winterhalder, Antoine M\'erand, Akke Corporaal, Guillaume Bourdarot, Stefan Kraus, Sasha Hinkley - - - Hedorah, the first yellow supergiant Kaiju star candidate at $z\approx3$ revealed by behind AS1063 - https://arxiv.org/abs/2601.11704 - arXiv:2601.11704v1 Announce Type: new -Abstract: We present a new free-form lens model for the $z=0.348$ galaxy cluster AS1063, based on previously spectroscopically confirmed lensed galaxies and new images from the GLIMPSE program. We use the ultra-deep data to identify new counterimages for previously confirmed (spectroscopically) lensed systems. We use the full set of spectroscopically confirmed systems to derive a new lens model, which is later used to confirm many of the previous lensed system candidates and discover new lensed system candidates in the images. We compute the geometric redshifts, time delays, and magnification for all counterimages (confirmed and not confirmed). Among the new systems we find a peculiar multiply lensed galaxy with a strong emission line at $\approx 4\, \mu$m that likely corresponds to H$-\beta$ and/or OIII at $z\approx 7.5$. This galaxy could be a little-red-dot or an extreme emission line galaxy. We also identify a yellow supergiant lensed star candidate at $z\approx 3.1$. This star shows some similarities with previous Kaiju stars and we nickname it "Hedorah", in honor of the famous yellow-eyed Kaiju. Previous lensed stars at $z>0.1$ are either blue supergiants or red supergiants, making Hedorah the first yellow supergiant discovered beyond $z=0.1$ and confirming that, despite their rarity, they can also be found at these redshifts. Since many Cepheid stars are yellow supergiants, we consider the possibility that Hedorah could also be the first Cepheid discovered at cosmological distances, but we conclude that Hedorah is more likely a hypergiant yellow star approaching the end of its life. Alternatively, Hedorah could be a small group of stars, although this is less likely based on Hedorah's peculiar colors and additionally may require the more exotic fuzzy dark matter to help explain the lack of counterimage. - oai:arXiv.org:2601.11704v1 astro-ph.GA - astro-ph.CO - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - J. M. Diego, J. M. Palencia, C. Goolsby, C. J. Conselice, D. J. Lagattuta, G. Mahler, J. Richard, K. Sharon, L. L. R. Williams + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Anna Heffernan - Inferring hemispheric asymmetries of stellar active regions through the information content of astrometric signals - https://arxiv.org/abs/2601.11707 - arXiv:2601.11707v1 Announce Type: new -Abstract: Photometric light curves suffer from fundamental degeneracies that limit surface information recovery. We demonstrate that astrometry enables access to complementary information through photocentre variations induced by rotating surface features. The forthcoming commissioning of microarcsecond-precision astrometric missions presents an opportunity to improve stellar surface mapping. This paper extends a previous theoretical framework for stellar surface mapping, along three primary directions: (1) we derive analytical selection rules showing that astrometry is sensitive to spherical harmonic modes not detectable via photometry, particularly odd-$\ell$ modes that encode north-south asymmetries; (2) we quantify the information content of combined photometric and astrometric observations, showing that the rank of observable modes grows faster for combined observations than for either technique alone, though the fraction of recoverable modes still decreases asymptotically with increasing spatial resolution; and (3) we reframe astrometric jitter-traditionally treated as noise in exoplanet studies-as a signal encoding stellar surface structure. Given the limited proposed target lists of high-precision astrometric missions, this capability is particularly valuable: understanding host star surfaces is crucial for both removing stellar signals from exoplanet detections and characterising star-planet interactions. We show that while Sun-like stars require sub-microarcsecond precision, evolved stars with angular diameter and larger spots present immediate opportunities with current technology, such as the Gaia mission. - oai:arXiv.org:2601.11707v1 - astro-ph.SR + Non-uniform Antenna Loading Effect on Embedded Element Patterns and Application to Fault Detection + https://arxiv.org/abs/2601.15367 + arXiv:2601.15367v1 Announce Type: new +Abstract: A new, iterative algorithm is presented to calculate the Embedded Element Pattern (EEP) tranformation from a set of patterns computed for a uniform antenna port loading (scaled identinty matrix) to a set of those computed for a non-uniform one (arbitrary diagonal matrix). This method proves particularly useful when inverting the computations to derive the non-uniform entries of the arbitrary load, given the minimum number of EEPs necessary, which disposes of the redundancy of other matrix-based computations and leads to numerically stable impedance fault calculation. As the EEPs are envisioned to be obtained primarily through measurement, our method is also tested with the inclusion of various noise components and its convergence is evaluated, suggesting the minimum SNR and fading level of the measurement apparatus, as well as the optimal choice of reference antenna to minimise the estimation error. + oai:arXiv.org:2601.15367v1 astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Conaire Deagan, Benjamin T. Montet - - - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) I: Motivation, sample, data reduction, and results overview - https://arxiv.org/abs/2601.11708 - arXiv:2601.11708v1 Announce Type: new -Abstract: The outer regions of planetary systems host dusty debris discs analogous to the Kuiper belt (exoKuiper belts), which provide crucial constraints on planet formation and evolution processes. ALMA dust observations have revealed a great diversity, and that some belts contain CO gas, whose origin and implications are uncertain. Most of this progress, however, has been limited by low-resolution observations. We conducted the first ALMA large programme dedicated to debris discs: the ALMA survey to Resolve exoKuiper belt Substructures (ARKS). We selected the 24 most promising belts to constrain their detailed radial and vertical structure, and to characterise the gas content. We constrained the radial and vertical distribution of dust, as well as the presence of asymmetries. For a subset of six belts with CO gas, we constrained the gas distribution and kinematics. To interpret these observations, we used a wide range of dynamical models. The first ARKS results are presented as a series of ten papers. We discovered that up to 33% of our sample exhibits multiple dusty rings. For highly inclined belts, we found that non-Gaussian vertical distributions are common and are indicative of multiple dynamical populations. We also found that 10 of the 24 belts present asymmetries. We find that the CO gas is radially broader than the dust, but this could be an effect of optical depth. At least one system shows non-Keplerian kinematics due to strong pressure gradients, which may have triggered a vortex that trapped dust in an arc. Finally, we find evidence that the micron-sized grains may be affected by gas drag in gas rich systems. ARKS has revealed a great diversity of structures in exoKuiper belts that may arise when they are formed in protoplanetary discs or subsequently via interactions with planets and/or gas. We encourage the community to explore the reduced data and data products. - oai:arXiv.org:2601.11708v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1051/0004-6361/202556489 - Volume 705, 2026, page A195 - S. Marino, L. Matr\`a, A. M. Hughes, J. Ehrhardt, G. M. Kennedy, C. del Burgo, A. Brennan, Y. Han, M. R. Jankovic, J. B. Lovell, S. Mac Manamon, J. Milli, P. Weber, B. Zawadzki, R. Bendahan-West, A. Fehr, E. Mansell, J. Olofsson, T. D. Pearce, A. Bayo, B. C. Matthews, T. L\"ohne, M. C. Wyatt, P. \'Abrah\'am, M. Bonduelle, M. Booth, G. Cataldi, J. M. Carpenter, E. Chiang, S. Ertel, A. S. Hales, Th. Henning, \'A. K\'osp\'al, A. V. Krivov, P. Luppe, M. A. MacGregor, J. P. Marshall, A. Mo\'or, S. P\'erez, A. A. Sefilian, A. G. Sepulveda, D. J. Wilner + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Georgios Kyriakou - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) IX: Gas-driven origin for the continuum arc in the debris disc of HD 121617 - https://arxiv.org/abs/2601.11709 - arXiv:2601.11709v1 Announce Type: new -Abstract: Debris discs were long considered to be largely gas-free environments governed by collisional fragmentation, gravitational stirring, and radiative forces. Recent CO detections show that gas is present, but its abundance and origin remain uncertain. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) revealed a narrow gas and dust ring in the disc HD 121617 with an asymmetric arc 40% brighter than the rest of the ring. We aim to constrain the total gas mass in HD 121617 assuming the dust arc is produced by hydrodynamical gas-dust interactions. We used the Dusty FARGO-ADSG code, modelling dust as Lagrangian particles, including radiation pressure and dust feedback, and varying the total gas mass. Simulations were compared to observations using radiative transfer. An unstable gas ring creates a size-dependent radial and azimuthal dust trap whose efficiency depends on gas mass. Two models, with 50 and 5 Earth masses of gas, reproduce both the ALMA band 7 arc and the outward offset of the VLT/SPHERE scattered-light ring via gas drag and radiation pressure. We infer a conservative gas-mass range of 2.5 to 250 Earth masses. If the ALMA asymmetry is caused by gas drag, the required gas mass compared with the observed CO implies substantial H2, consistent with primordial gas. HD 121617 would then be a hybrid disc between protoplanetary and debris stages. Since a planet could also create an arc, future observations are needed to distinguish these scenarios. - oai:arXiv.org:2601.11709v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Digging into the Interior of Hot Cores with ALMA (DIHCA). VII. Disk candidates around high-mass stars and evidence of anisotropic infall + https://arxiv.org/abs/2601.15371 + arXiv:2601.15371v1 Announce Type: new +Abstract: We study the kinematics of condensations in 30 fields forming high-mass stars with ALMA at a high-resolution of ~0.08'' on average (~230 au). The presence of disks is important for feeding high-mass stars without feedback halting growth as their masses increase. In the search for velocity gradients resembling rotation that can reveal the presence of disks, we analyze the emission of gas tracers in 49 objects using CH$_3$OH, CH$_3$CN, and tentative detections of HNCO and cis-HCOOH. Most of the velocity distributions show velocity gradients indicative of rotation. We reveal a total of 32 disk candidates, the largest sample to date that has been uniformly analyzed at a few hundred au scales in the high-mass regime. Their position-velocity maps are generally asymmetric with one side brighter than the opposite. We successfully fit a power law to the position-velocity maps of the disk candidates and find indices between -0.5 (Keplerian rotation) and -1 (rotation under specific angular momentum conservation) with a median of -0.7. Under Keplerian rotation assumption, we estimate central masses, uncorrected for inclination, ranging between 7 to 45 M$_\odot$. Excluding outliers, the disk candidates are relatively more compact (<200 au) and less massive (<5 M$_\odot$) than previous results at coarser angular resolution. We calculate an average Toomre-$Q$ parameter and find that most are gravitationally unstable (median of 0.5). We conclude that these observations offer the first opportunity to separate the disk and envelope components of hot cores on a statistically significant sample, and confirm that anisotropic collapse plays an role in feeding high-mass (proto)stars. + oai:arXiv.org:2601.15371v1 + astro-ph.SR + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Philipp Weber, Sebasti\'an P\'erez, Cl\'ement Baruteau, Sebastian Marino, Fernando Castillo, Marija R. Jankovic, Tim Pearce, Mark C. Wyatt, Antranik A. Sefilian, Johan Olofsson, Gianni Cataldi, Joshua B. Lovell, Carlos del Burgo, A. Meredith Hughes, Sorcha Mac Manamon, Aoife Brennan, Luca Matr\`a, Julien Milli, Brianna Zawadzki, Eugene Chiang, Meredith MacGregor, David J. Wilner, Myriam Bonduelle, John Carpenter, Yinuo Han, \'Agnes K\'osp\'al, Patricia Luppe + Fernando A. Olguin, Patricio Sanhueza, Yoko Oya, Adam Ginsburg, Maria T. Beltr\'an, Kaho Morii, Roberto Galv\'an-Madrid, Huei-Ru Vivien Chen, Qiuyi Luo, Kei E. I. Tanaka, Suinan Zhang, Yu Cheng, Fumitaka Nakamura, Shanghuo Li, Kotomi Taniguchi, Guido Garay, Qizhou Zhang, Masao Saito, Takeshi Sakai, Xing Lu, Jixiang Weng, Andr\'es E. Guzm\'an - Resonant Scattering of the He I 1.0833$\mu$m Triplet in H II Regions: Emission Spectra - https://arxiv.org/abs/2601.11710 - arXiv:2601.11710v1 Announce Type: new -Abstract: Resonant scattering of He I 1.0833$\mu$m triplet photons by metastable He 2 $^3$S$_1$ is studied for optical depths characteristic of H II regions. Regions with large He 2 $^3$S$_1$ column densities are predicted to have unusually broad, multi-peaked 1.0833$\mu$m emission profiles, with the centroid blue-shifted by up to $\sim$14 km/s relative to other lines. The feature FWHM can exceed 100 km/s for some regions. Resonant trapping enhances dust absorption and reduces the He I 1.0833$\mu$m emission. Care must be taken when using the He I 1.0833$\mu$m/H I 1.0941$\mu$m (Pa$\gamma$) ratio to estimate the He$^+$/H$^+$ ratio. Predicted spectra are computed for examples, including M-17B and NGC3603 in the Galaxy, and a star-forming region in M51. Observations of the 1.0833$\mu$m triplet with spectrometers such as NIRSPEC, CARMENES, or X-Shooter can confirm the predicted effects of resonant scattering in H II regions, and constrain the nebular conditions. - oai:arXiv.org:2601.11710v1 + Hierarchical bayesian inference: constraining population distribution of dark matter halo shapes via stellar streams + https://arxiv.org/abs/2601.15373 + arXiv:2601.15373v1 Announce Type: new +Abstract: Stellar streams, the debris of tidally disrupted satellites, trace their host's gravitational potential and thus probe dark matter halo structure. While six-dimensional phase-space data of Galactic streams enable precise dark matter halo modelling in the Milky Way, streams around external galaxies are typically available only as low surface brightness features without kinematics (i.e. two-dimensional photometric data), providing only weak constraints when considered individually. We present a hierarchical Bayesian framework that infers the population distribution of halo flattening using only projected stream tracks. Streams are forward-modelled in StreaMAX, a new JAX-accelerated particle-spray package that achieves orders of magnitude faster stream generation when compared to traditional methods. For each stream we fit an axisymmetric dark matter halo model and obtain a posterior on the flattening. These posteriors are then combined through hierarchical reweighting to constrain the population distribution. Using mock data, we show that individual fits recover the correct flattening with modest precision and exhibit projection-induced multi-modalities. Nevertheless, aggregating these fits yields accurate and confident constraints on the underlying population distribution of dark matter halo morphologies, clearly distinguishing between oblate, spherical, and prolate populations. The total computational cost scales linearly with sample size. Our results demonstrate that ensembles of purely photometric streams carry sufficient information to constrain dark matter halo shapes in external galaxies at the population level. With the forthcoming samples from Euclid and Rubin/LSST, this approach offers a practical path to population-level inferences of halo morphology without any kinematic measurements. + oai:arXiv.org:2601.15373v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-sa/4.0/ - B. T. Draine - - - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) VIII: A dust arc and non-Keplerian gas kinematics in HD 121617 - https://arxiv.org/abs/2601.11711 - arXiv:2601.11711v1 Announce Type: new -Abstract: ExoKuiper belts around young A-type stars often host CO gas, whose origin is still unclear. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) includes 6 of these gas-bearing belts, to characterise their dust and gas distributions and investigate the gas origin. As part of ARKS, we observed the gas-rich system HD121617 and discovered an arc of enhanced dust density. In this paper, we analyse in detail the dust and gas distributions and the gas kinematics of this system. We extracted radial and azimuthal profiles of the dust (in the millimetre and near-infrared) and gas emission ($^{12}$CO and $^{13}$CO) from reconstructed images. To constrain the morphology of the arc, we fitted an asymmetric model to the dust emission. To characterise the gas kinematics, we fitted a Keplerian model to the velocity map and extracted the azimuthal velocity profile by deprojecting the data. We find that the dust arc is narrow (1-5 au wide at a radius of 75 au), azimuthally extended, and asymmetric; the emission is more azimuthally compact in the direction of the system's rotation, and represents 13% of the total dust mass (0.2$M_\oplus$). The arc is much less pronounced or absent for small grains and gas. Finally, we find strong non-Keplerian azimuthal velocities at the inner and outer wings of the ring, as was expected due to strong pressure gradients. The dust arc resembles the asymmetries found in protoplanetary discs, often interpreted as the result of dust trapping in vortices. If the gas disc mass is high enough ($\gtrsim20M_\oplus$, requiring a primordial gas origin), both the radial confinement of the ring and the azimuthal arc may result from dust grains responding to gas drag. Alternatively, it could result from planet-disc interactions via mean motion resonances. Further studies should test these hypotheses and may provide a dynamical gas mass estimate in this CO-rich exoKuiper belt. - oai:arXiv.org:2601.11711v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1051/0004-6361/202556493 - Volume 705, 2026, Page A202 - S. Marino, V. Gupta, P. Weber, T. D. Pearce, A. Brennan, S. P\'erez, S. Mac Manamon, L. Matr\`a, J. Milli, M. Booth, C. del Burgo, G. Cataldi, E. Chiang, Y. Han, Th. Henning, A. M. Hughes, M. R. Jankovic, \'A. K\'osp\'al, J. B. Lovell, P. Luppe, E. Mansell, M. A. MacGregor, A. Mo\'or, J. Olofsson, A. A. Sefilian, D. J. Wilner, M. C. Wyatt, B. Zawadzki + http://creativecommons.org/licenses/by/4.0/ + David Chemaly, Elisabeth Sola, Vasily Belokurov, Sergey Kosposov, GyuChul Meyong, HanYuan Zhang, Denis Erkal - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) IV: CO gas imaging and overview - https://arxiv.org/abs/2601.11712 - arXiv:2601.11712v1 Announce Type: new -Abstract: CO gas is detected in a significant number of debris discs, but its origin and evolution remains unclear. Key constraints are its mass and spectro-spatial distribution, which are coupled through optical depth and have only been analysed at low to moderate resolution so far. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) is the first ALMA large program to target debris discs at high spectro-spatial resolution. We used $^{12}$CO and $^{13}$CO J=3-2 line data of 18 ARKS debris belts, 5 of which were already known to host gas, to analyse the spectro-spatial distribution of CO, constrain the gas masses, and to search for gas in the remaining systems. We developed a line-imaging pipeline and produced line cubes for each disc, with a spatial resolution down to $\sim$70 mas and spectral resolution of 26 m s$^{-1}$. Using spectro-spatial shifting and stacking, we produced high signal-to-noise maps, and radial and spectral profiles that reveal the distribution and kinematics of gas in 5 gas-bearing discs. For these discs, we constrained the inner radius of the $^{12}$CO, and found the radial brightness profile of CO peaked interior to the dust ring, but that CO was more radially extended than the dust. We present the first radially resolved $^{12}$CO/$^{13}$CO isotopologue flux ratios in gas-bearing debris discs, which are constant with radius for the majority of systems, indicating $^{12}$CO and $^{13}$CO are both optically thick or thin throughout the discs. We report CO line fluxes/upper limits for all systems and optical depth dependant masses for the 5 gas-bearing systems. Finally, we analysed the $^{12}$CO J=3-2 line luminosities for the ARKS debris discs and discs from the literature. We confirm that gas is mostly detected in young systems. However, the high scatter seen in young/high fractional luminosity systems indicates no trend within the systems with detected gas. - oai:arXiv.org:2601.11712v1 - astro-ph.EP + What factors shape the radio luminosity of star-forming galaxies? A new calibration from LoTSS-DR2 + https://arxiv.org/abs/2601.15374 + arXiv:2601.15374v1 Announce Type: new +Abstract: Radio observations offer a dust-unobscured view of galaxy star formation via the radio continuum-star formation rate (RC--SFR) relation. Emerging evidence of a stellar mass dependence in the RC--SFR relation raises the broader question of how other galaxy properties may influence this relation. In this work, we study the dependence of the global RC--SFR relation on galaxy properties in local ($z\,\leq$\,0.3) star-forming galaxies (SFGs) using the second data release of the LOFAR Two-Metre Sky Survey (LoTSS-DR2). Employing a non-parametric decision-tree regression algorithm, we identify the most important galaxy properties for estimating the radio luminosity using a sample of 18,828 emission-line-classified SFGs based on spectroscopic data from the SDSS-DR8. Along with the spectroscopically obtained SFRs and stellar mass values, we also use SFRs and stellar masses derived using photometric SED-fitting from the \textit{GALEX}--SDSS--\textit{WISE} Legacy Catalogue (GSWLC) for the same sample. We find that a galaxy's SFR is most important for predicting the radio luminosity, followed by the stellar mass, at $>5\sigma$ significance. Complementing the LoTSS catalogue 150\,MHz flux densities with aperture photometry for the rest of the emission-line classified sample (35,099 galaxies in total), we obtain a new calibration of the RC--SFR relation, which does not change significantly whether we use spectroscopic or photometrically derived SFRs and stellar masses, despite the fact that the methods probe star formation on different characteristic timescales. Our results highlight the utility of decision-tree algorithms for handling censored radio-selected galaxy samples, which will be useful for future spectroscopic surveys of radio sources. + oai:arXiv.org:2601.15374v1 astro-ph.GA - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1051/0004-6361/202556605 - A&A 705, A198 (2026) - S. Mac Manamon, L. Matr\`a, S. Marino, A. Brennan, Y. Han, M. R. Jankovic, P. Weber, M. Bonduelle, J. M. Carpenter, G. Cataldi, A. M. Hughes, A. K\'osp\'al, J. P. Marshall, B. C. Matthews, J. Milli, A. Mo\'or, K. \"Oberg, S. P\'erez, A. A. Sefilian, D. J. Wilner, M. C. Wyatt, E. Chiang, A. S. Hales, J. B. Lovell, P. Luppe, M. A. MacGregor, T. Pearce, M. Booth, C. del Burgo, A. Fehr, E. Mansell, B. Zawadzki + Shravya Shenoy, Daniel J. B. Smith, Sarah K. Biddle, G\"ulay G\"urkan, Martin J. Hardcastle, Marina I. Arnaudova, Soumyadeep Das, Luke R. Holden, Gaoxiang Jin, Leah K. Morabito, Huub J. A. R\"ottgering - Blobs and Blurs: A Citizen Science-Identified Catalog of Diffuse Galaxies in the Fornax Cluster - https://arxiv.org/abs/2601.11715 - arXiv:2601.11715v1 Announce Type: new -Abstract: We present a catalog of 643 diffuse galaxies identified through a citizen science search of the Fornax cluster, of which we estimate 21.8% are nucleated (139/637; 6 inconclusive). This marks the first crowd-sourced effort to construct a cluster-scale census of diffuse galaxies. These objects were visually identified using a combination of the Fornax Deep Survey and Dark Energy Camera Legacy Survey imaging across 26 deg$^2$. Over 1,400 volunteers cataloged the candidates within this sky area at a rate of 1.15 days/deg$^2$. Our catalog is highly complete relative to existing dwarf catalogs of Fornax ($> 80\%$ of objects recovered) down to an effective radius $r_{\mathrm{eff}} = 5^{\prime \prime}$, the minimum size we suggested volunteers classify, and to an effective r-band surface brightness as faint as $\langle \mu_r \rangle \simeq26$ mag arcsec$^{-2}$. We detect 97 candidates that existing automated searches of Fornax did not find and three candidates not found by any prior search, automated or visual. The stellar mass distribution of our sample is consistent with similar dwarf studies of Fornax, with the nucleated fraction peaking at 80% for a host galaxy mass of $\sim$10$^{8.5}M_{\odot}$. The efficiency and completeness of our catalog thus establishes citizen science as a valuable tool for mapping diffuse galaxy populations in future sky surveys, such as the Legacy Survey of Space and Time. - oai:arXiv.org:2601.11715v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + The Back-in-time Void Finder: dynamical identification of cosmic voids through optimal transport reconstruction + https://arxiv.org/abs/2601.15378 + arXiv:2601.15378v1 Announce Type: new +Abstract: Cosmic voids have increasingly emerged as a powerful cosmological probe. However, their large spatial extent and intrinsically underdense environments make their identification highly sensitive to shot noise, redshift-space distortions (RSD), and observational systematics, particularly for topological and density-based void definitions. We introduce the Back-In-Time Void Finder (BitVF), a novel dynamical and physically motivated algorithm that identifies cosmic voids as regions of negative divergence of the Lagrangian displacement field reconstructed from the present-day tracer distribution. The reconstruction relies on an optimized discrete optimal transport algorithm that recovers the backward-in-time dynamics of tracers, naturally accounting for tracer bias without relying on cosmological assumptions. We validate BitVF against the widely used topological void finder REVOLVER using high-resolution N-body simulations, showing that it produces void catalogs with smoother and more physically motivated density profiles, as well as abundances that are more stable under tracer subsampling and shot noise. We further apply it to realistic DESI-like mock light-cone galaxy catalogs, demonstrating that it intrinsically mitigates redshift-space systematic effects, preserving real-space void size functions more faithfully than topological methods. Modeling RSD, the reconstruction can be combined with a fiducial cosmology and an assumed tracer bias within a bias-corrected Kaiser framework, yielding reconstructed-space void catalogs consistent with real-space statistics across redshift. Its performance is characterized as a function of the main internal parameters, showing an optimal balance between accuracy, computational efficiency, and applicability to stage IV galaxy surveys. BitVF will be publicly released within the CosmoBolognaLib. + oai:arXiv.org:2601.15378v1 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Nicolas Mazziotti, Michael G. Jones, Donghyeon J. Khim, David J. Sand, Paul Bennet + Simone Sartori, Sofia Contarini, Elena Sarpa, Giulia Degni, Federico Marulli, Stephanie Escoffier, Lauro Moscardini - Discovery of High X-Ray Polarization from the Neutron Star Low-Mass X-Ray Binary Cyg X-2 in the Horizontal Branch - https://arxiv.org/abs/2601.11718 - arXiv:2601.11718v1 Announce Type: new -Abstract: We present results from simultaneous X-ray polarimetric and spectroscopic observations of the bright neutron star low-mass X-ray binary Cyg X-2, performed by the Imaging X-ray Polarimetry Explorer (IXPE) and the Nuclear Spectroscopic Telescope Array (NuSTAR). IXPE detected significant polarization (15 sigma) from the source in the 2-8 keV energy band with an average polarization degree (PD) of 4.5% +/- 0.3% and a polarization angle (PA) of 128 +/- 2 degrees as the source moved along the horizontal branch of its Z-track. The PD increases with energy reaching 9.9% +/- 2.8% in the 7-8 keV band, with no evidence for energy-dependent variation in the PA. The PA is roughly consistent with previous measurements obtained during the normal and flaring branches and also with the known radio jet axis. From spectropolarimetric analysis, the main contribution to the polarized radiation is due to Comptonized photons, but the polarization is higher than predicted in typical spreading layer geometries. The observed high polarization may be due to a combination of a highly polarized reflected component and a moderately polarized spreading layer on the neutron star surface or produced by electron scattering in an equatorial wind. - oai:arXiv.org:2601.11718v1 + Optimizing Optical Searches for Supermassive Black Hole Binaries in AGN Light Curves: Fourier versus Bayesian Periodicity Detection + https://arxiv.org/abs/2601.15379 + arXiv:2601.15379v1 Announce Type: new +Abstract: Simulations predict that supermassive black hole binaries (SMBHBs) will exhibit periodic brightness variations that may exceed the stochastic variability intrinsic to active galactic nuclei (AGN). In this paper, we simulate SMBHBs with damped random walk (DRW) AGN variability and an added sinusoidal signal from the orbital motion, and test three methods -- the Generalized Lomb Scargle Periodogram (GLSP), the nested Bayesian sampler (NBS), and the Weighted Wavelet Z-Transform (WWZ) -- to determine which is best at recovering the periodicity. Our simulated light curves follow the properties of the Catalina Real-Time Transient Survey (CRTS), Legacy Survey of Space and Time (LSST), and Zwicky Transient Facility (ZTF) to best inform current and future SMBHB searches. We map a broad range of parameter space and identify which DRW-only light curves best mimic periodicity and pass each method's model selection. The NBS performs best at detecting periodicity and filtering out DRW-only light curves. Combined candidate selection with both the NBS and GLSP significantly reduces false positive rates with marginal impact to true positive rates. With this joint model selection pipeline, we find the lowest false positive rates in ZTF-like simulations and the highest detection rates in LSST-like simulations. Using a modified computation of the False Alarm Probability (FAP) with GLSP, we efficiently triage LSST AGN light curves (~10^7 light curves in ~10-30 hours) and achieve true- and false- positive rates of ~40% and ~0.5%, respectively. + oai:arXiv.org:2601.15379v1 + astro-ph.GA astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Andrea Gnarini, Swati Ravi, Philip Kaaret, Anna Bobrikova, Juri Poutanen, Sofia V. Forsblom, Francesco Ursini, Maria Cristina Baglio, Stefano Bianchi, Fiamma Capitanio, Massimo Cocchi, Maria Alejandra Diaz Teodori, Sergio Fabiani, Ruben Farinelli, Giorgio Matt, Mason Ng, Alexander Salganik, Paolo Soffitta, Antonella Tarana, Silvia Zane + Sebastian Banaszak, Caitlin Witt, Adam Miller - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS). X. Interpreting the peculiar dust rings around HD 131835 - https://arxiv.org/abs/2601.11732 - arXiv:2601.11732v1 Announce Type: new -Abstract: Dusty discs detected around main-sequence stars are thought to be signs of planetesimal belts in which the dust distribution is shaped by collisional and dynamical processes, including interactions with gas if present. The debris disc around the young A-type star HD 131835 is composed of two dust rings at ~65 au and ~100 au, a third unconstrained innermost component, and a gaseous component centred at ~65 au. New ALMA observations show that the inner of the two dust rings is brighter than the outer one, in contrast with previous observations in scattered light. We explore two scenarios that could explain these observations: the two dust rings might represent distinct planetesimal belts with different collisional properties, or only the inner ring might contain planetesimals while the outer ring consists entirely of dust that has migrated outwards due to gas drag. To explore the first scenario, we employed a state-of-the-art collisional evolution code. To test the second scenario, we used a simple dynamical model of dust grain evolution in an optically thin gaseous disc. Collisional models of two planetesimal belts cannot fully reproduce the observations by only varying their dynamical excitation, and matching the data through a different material strength requires an extreme difference in dust composition. The gas-driven scenario can reproduce the location of the outer ring and the brightness ratio of the two rings from scattered light observations, but the resulting outer ring is too faint overall in both scattered light and sub-millimetre emission. The dust rings in HD 131835 could be produced from two planetesimal belts, although how these belts would attain the required extremely different properties needs to be explained. The dust-gas interaction is a plausible alternative explanation and deserves further study using a more comprehensive model. - oai:arXiv.org:2601.11732v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Blazars define a stable celestial reference frame + https://arxiv.org/abs/2601.15381 + arXiv:2601.15381v1 Announce Type: new +Abstract: Recent work has shown that optical-radio position offsets and radio position variability are inversely correlated with the photometric variability of active galactic nuclei (AGN). A key prediction of these findings is that a reference frame constructed using highly photometrically variable AGN should be more stable than a frame that does not account for variability and that variability can be used to optimally weight all sources in order to maximize frame stability. Using ICRF3 matched to Gaia DR3, we employed a bootstrap method to estimate the multi-epoch stability of frames constructed using AGN selected at varying levels of photometric variability. We fit vector spherical harmonics to the coordinate differences between the three ICRF3 frames (S/X, K, and X/Ka) and Gaia and quantified the statistical dispersion as a function of blazar-like (high variability), quasar-like (low variability), and intermediate-variability class. An S/X reference frame constructed using blazars exceeds the stability of a frame constructed with quasars by a factor of 6 and is twice as stable as the ICRF3 defining sources. At K and X/Ka, a blazar-based frame matches or exceeds the stability of the defining sources by a factor of 1.4 in the case of X/Ka and exceeds the stability of a frame based on quasars by over a factor of 2 in both cases. The smaller improvement at K and X/Ka is likely because sources selected at higher frequency are more likely to be blazars. We derived a variability-based astrometric covariance scaling method that results in factor of 2 reduction in frame distortions and instabilities between S/X and Gaia, with a mild improvement for K but no difference for X/Ka, which is dominated by known distortions. Our results confirm the prediction that an optimal weighting of the link between the optical and radio celestial reference frames is enabled by accounting for photometric variability. + oai:arXiv.org:2601.15381v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1051/0004-6361/202556637 - M. R. Jankovic, N. Pawellek, J. Zander, T. L\"ohne, A. V. Krivov, J. Olofsson, A. Brennan, J. Milli, M. Bonduelle, M. C. Wyatt, A. A. Sefilian, T. Pearce, S. Mac Manamon, Y. Han, S. Marino, L. Matr\'a, A. Mo\'or, M. Booth, E. Chiang, E. Mansell, P. Weber, A. M. Hughes, D. J. Wilner, P. Luppe, B. Zawadzki, C. del Burgo, \'A. K\'osp\'al, S. P\'erez, J. M. Carpenter, Th. Henning + Nathan Secrest, Sebastien Lambert - Using Astrometry to Break Degeneracies in Stellar Surface Mapping - https://arxiv.org/abs/2601.11737 - arXiv:2601.11737v1 Announce Type: new -Abstract: Astrometric jitter noise arises when starspots on a rotating stellar surface move in and out of view, shifting the photocenter. This noise may limit our ability to detect and weigh small, sub-Neptune-sized planets around active stars. By deriving a linear forward model for the astrometric jitter signal of a rotating star in a spherical-harmonic coordinate system, we show that jitter noise can be used to reconstruct surface-brightness maps and, in principle, disentangle jitter from stellar reflex motion due to an orbiting planet. Furthermore, we show that astrometry and photometry probe complementary surface information: photometry measures even-degree spherical harmonic surfaces that are symmetric about the equator, while astrometry measures odd-degree modes. Their joint use, therefore, breaks degeneracies in surface mapping. Our model further quantifies the variation in the astrometric signal with inclination angle, which is foundational for studies of worst-case configurations of astrometric star-spot noise. For example, we show that pole-on stellar inclinations lead to poorly constrained inversions, as any stellar surface produces a purely circular astrometric jitter signal. We characterize the degeneracy in jointly identifying the stellar surface and stellar inclination, and develop a surface estimation approach. Using this approach, we present example simulations and reconstructions that demonstrate the use of astrometry data alongside light-curve data to improve stellar surface mapping and localize spot positions in latitude and longitude. With forthcoming high-precision Gaia astrometry, astrometric surface mapping provides a promising new approach to probe stellar activity. - oai:arXiv.org:2601.11737v1 - astro-ph.SR - astro-ph.EP - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + A Stratification in Magnetic Field Structures: The Radio Outflow in NGC 4151 + https://arxiv.org/abs/2601.15382 + arXiv:2601.15382v1 Announce Type: new +Abstract: The nature of radio outflows in radio-quiet AGN remains poorly understood. In this study, we present kpc-scale polarization observations of the Seyfert galaxy NGC\,4151 using the Karl G. Jansky Very Large Array (VLA) in B-array at 3 and 10 GHz. We find that the inferred magnetic (B-) field structures show a stratification: a `spine-sheath'-like structure, with fields perpendicular to the jet direction in the `spine' and parallel in the `sheath', is observed in the higher resolution (0.5 arcsec) image at 10 GHz. In addition, a `wind'-like component with B-fields perpendicular to the radio outflow is observed in the 3 GHz image (resolution 2 arcsec); this feature is prominent along the `receding' (eastern) jet direction. Rotation measure (RM) ranges from $-230$ to 250 rad m$^{-2}$ over the polarized regions, indicating a low-electron-density ($10^{-2}-10^{-3}$ cm$^{-3}$) tenuous medium surrounding the source causing Faraday rotation. A {tentative} RM gradient of $+75$ to $-25$ rad m$^{-2}$ is observed transverse to the northern `wind' component, while a similar gradient with opposite sign is seen across the southern `wind' component, suggestive of a helical magnetic field threading the outflow. Based on an analysis of the available radio and X-ray data, we conclude that the stratified radio outflow in NGC 4151 is magnetically-driven. The bi-conical radio `wind' is found to be massive ($1050-3200 M_\odot$) with a high mass outflow rate ($0.01-0.03$ M$_\odot$ yr$^{-1}$) but low in kinetic power ($<0.01$% of L$_{\rm{bol}}$), making it less impactful for galactic-scale feedback. Our study suggests that radio-quiet AGN may also host magnetically dominant jets and winds, even while their jets are smaller and weaker compared to radio-loud AGN. + oai:arXiv.org:2601.15382v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Jamila Taaki, Lia Corrales, Alfred O. Hero III + http://creativecommons.org/licenses/by/4.0/ + Salmoli Ghosh (NCRA-TIFR), P. Kharb (NCRA-TIFR), E. Costantini (SRON, API-UvA, The Netherlands), J. Gallimore (Bucknell University), D. Williams-Baldwin (JBCA, The University of Manchester), M. Mehdipour (University of Michigan) - Black hole accretion disks with outflows II. Time dependent Green's function solutions in Newtonian gravity - https://arxiv.org/abs/2601.11754 - arXiv:2601.11754v1 Announce Type: new -Abstract: We present Green's function solutions of the Newtonian time-dependent thin disk equations in the presence of outflows, showing that simple and exact analytical expressions exist in various natural limits of the problem. These Green's functions are mathematically very similar to the classical Lynden-Bell & Pringle solutions in the absence of outflows, but differ strongly in their precise physical details and observational implications. Solutions are presented for phenomenological radius-dependent outflows which both do and do not torque the local accretion flow, and for outflows which are launched proportional to the local accretion rate. Generically, outflows lead to a more rapid decay of the bolometric luminosity of the disk, flatten the radial dependence of the disk temperature, and suppress variability in the accretion rate at small radii and low frequencies (on long timescales). Observational implications of these four results are discussed in detail. - oai:arXiv.org:2601.11754v1 + An Investigation of 5-year Simultaneous X-ray and Radio Light Curves of the Dwarf Seyfert Galaxy UGC 6728 + https://arxiv.org/abs/2601.15383 + arXiv:2601.15383v1 Announce Type: new +Abstract: We present serendipitous simultaneous radio and X-ray light curves of the dwarf Seyfert galaxy UGC 6728 spanning 5 years. The X-ray light curve exhibits a flaring period, followed by a gradual rise and decline. Throughout these events, the X-ray hardness ratio and spectrum do not change significantly. The radio flux is constant, as far as can be determined from its sparse sampling, until the end of the X-ray flare, then decreases by a factor of two by the midpoint of the gradual X-ray rise before returning to baseline at the end of the X-ray decline. We interpret this behavior in light of a similar event recently reported in NGC 2992, in which there is a temporary obscuration of the radio source by a blob of plasma ejected by a magnetic reconnection in the accretion disk. The energetics of the X-ray flare are consistent with those expected from magnetic disk activity. As in NGC 2992, the X-ray spectrum does not evolve during the obscuration event. We also discuss the possibility that the observed phenomena are due to normal AGN coronal flaring and variability, which is plausible but unlikely given the lack of spectral variation. + oai:arXiv.org:2601.15383v1 + astro-ph.GA astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Andrew Mummery + Krista Lynne Smith, Macon Magno, Michael Koss - The impact of attenuation on cosmic-ray chemistry: I. Abundances and chemical calibrators in molecular clouds - https://arxiv.org/abs/2601.11761 - arXiv:2601.11761v1 Announce Type: new -Abstract: The chemistry of shielded molecular gas is primarily driven by energetic, charged particles dubbed cosmic rays (CRs), in particular those with energies under 1 GeV. CRs ionize molecular hydrogen and helium, the latter of which contributes greatly to the destruction of molecules. CR ionization initiates a wide range of gas-phase chemistry, including pathways important for the so-called "carbon cycle", C$^+$/C/CO. Therefore, the CR ionization rate, $\zeta$, is fundamental in theoretical and observational astrochemistry. Although observational methods show a wide range of ionization rates -- varying with the environment, especially decreasing into dense clouds -- astrochemical models often assume a constant rate. To address this limitation, we employ a post-processed gas-phase chemical model of a simulated dense molecular cloud that incorporates CR energy losses within the cloud. This approach allows us to investigate changes in abundance profiles of important chemical tracers and gas temperature. Furthermore, we analyze analytical calibrators for estimating $\zeta$ in dense molecular gas that are robust when tested against a full chemical network. Additionally, we provide improved estimations of the electron fraction in dense gas for better consistency with observational data and theoretical calibrations for UV-shielded regions. - oai:arXiv.org:2601.11761v1 + An Analysis of AGN Feedback in the Compact Galaxy Group Stephan's Quintet + https://arxiv.org/abs/2601.15384 + arXiv:2601.15384v1 Announce Type: new +Abstract: Compact galaxy groups are ideal laboratories for studying the effects of interactions between AGN and multiple nearby galaxies. Recent JWST observations of the nearby compact group Stephan's Quintet highlight tidal flows between the interacting galaxies as well as outflows from the active galaxy NGC 7319. To study the kinematics on a large scale throughout the group, we obtained spatially-resolved long-slit spectra of Stephan's Quintet at multiple slit positions with Apache Point Observatory's Kitt Peak Ohio State Multi-Object Spectrograph. We fit multiple Gaussians to the H$\alpha$ $\lambda$6563 \r{A} and [N II] $\lambda\lambda$6548, 6583 \r{A} emission lines to isolate the different kinematic components. We used the kinematics to develop the first biconical outflow model of the narrow-line region of NGC 7319. Using a combination of galactic rotation models, biconical outflow models, and kinematic maps of the ionized gas, we disentangled the outflows, rotation, and tidal flows in the group. We found outflow radial velocities up to 550 km s$^{-1}$ peaking at 2.6 kpc from the central supermassive black hole, and a transition from AGN-powered outflows to gravitationally-powered tidal flows at a projected distance between 2.4 -- 6.3 kpc. We performed a line ratio analysis and determined the gas shows Seyfert-like ionization out to 6.3 kpc (projected), which supports our finding that gas outside this radius is predominantly powered by tidal flows. Our separation of kinematic components in Stephan's Quintet will enable future studies of the physical conditions and dynamical forces in the ionized gas to better quantify the feeding and feedback processes of AGN in compact groups. + oai:arXiv.org:2601.15384v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Arghyadeb Roy, Brandt A. L. Gaches, Jonathan C. Tan - - - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS): VI. Asymmetries and offsets - https://arxiv.org/abs/2601.11766 - arXiv:2601.11766v1 Announce Type: new -Abstract: Asymmetries in debris discs provide unique clues to understand the evolution and architecture of planetary systems.** The aim of the ALMA survey to Resolve exoKuiper belt Substructures (ARKS) is to expand our understanding of radial and vertical dust structures, as well as gas distributions and kinematics, in debris discs.** Here, in ARKS~VI, we present a systematic analysis of the asymmetries and stellocentric offsets present in the ALMA continuum data for the ARKS survey. Our aims are to identify asymmetries in debris disc dust distributions, quantify debris disc asymmetry properties, and discuss the potential origins of debris disc asymmetries.** We utilised empirical methods to identify emission asymmetries** and the presence of offset emission between disc centres and the locations of the host stars, via an analysis of their calibration procedures and disc properties. We associated observational asymmetry types** and plausible physical classes** associated with each source. We show that there are ten systems, almost half of the ARKS sample, that host either a continuum emission asymmetry or offset emission. Three systems host offsets (HD15115, HD32297, and HD109573 (HR4796)), four host azimuthal asymmetries (HD9672 (49Ceti), HD92945, HD107146, and HD121617), two host an asymmetry in their major axis (HD10647 (q$^1$ Eri), and HD39060 ($\beta$ Pic)), and one hosts an asymmetry in their minor axis (HD61005). We attribute the offset asymmetries to non-zero eccentricities, and three of the azimuthal asymmetries to arcs. The presence of an asymmetry or offset in the ARKS sample appears to be correlated with the fractional luminosity of cold dust.** Conclusions: This study demonstrates that debris disc asymmetries in the ARKS sample are common, and plausibly so in the wider population of debris discs at (sub)-millimetre wavelengths.** ** = ABRIDGED FOR ARXIV: FULL ABSTRACT IN PAPER - oai:arXiv.org:2601.11766v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.1051/0004-6361/202556568 - J. B. Lovell, A. S. Hales, G. M. Kennedy, S. Marino, J. Olofsson, A. M. Hughes, E. Mansell, B. C. Matthews, T. D. Pearce, A. A. Sefilian, D. J. Wilner, B. Zawadzki, M. Booth, M. Bonduelle, A. Brennan, C. del Burgo, J. M. Carpenter, G. Cataldi, E. Chiang, A. Fehr, Y. Han, Th. Henning, A. V. Krivov, P. Luppe, J. P. Marshall, S. Mac Manamon, J. Milli, A. Mo\'or, M. C. Wyatt, S. Ertel, M. R. Jankovic, \'A. K\'osp\'al, M. A. MacGregor, L. Matr\`a, S. P\'erez, P. Weber + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.3847/1538-4357/ae2796 + Maura Kathleen Shea (Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA), D. Michael Crenshaw (Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA), Travis C. Fischer (AURA for ESA, Space Telescope Science Institute, Baltimore, MD, USA), Mitchell Revalski (Space Telescope Science Institute, Baltimore, MD, USA), Julia Falcone (Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA), Beena Meena (Space Telescope Science Institute, Baltimore, MD, USA), Zo Chapman (College of Computer Science, Georgia Institute of Technology, Atlanta, GA, USA), Jacob Tutterow (Kapteyn Astronomical Institute, University of Groningen, AV Groningen, the Netherlands), Madeline Davis (Department of Physics and Astronomy, Georgia State University, Atlanta, GA, USA), Kesha Patel (Department of Physics and Astronomy, Tufts University, Medford, MA, USA) - A Multi-Wavelength Study of Comet C/2022 E3 (ZTF): Complementary ALMA and JWST Investigations of Water and Methanol in Cometary Comae - https://arxiv.org/abs/2601.11767 - arXiv:2601.11767v1 Announce Type: new -Abstract: Long-period comets, which are often considered to be representative of material in the protoplanetary disk that formed the Solar System, are ideal to investigate the question of chemical inheritance in astronomy. Determining the chemistry of comets, both individually and as a population, has become of great importance in comparative studies against sources representative of evolutionary precursors to planetary systems. Contemporaneous observations of long-period comet C/2022 E3 (ZTF) were obtained with the JWST and the Atacama Large Millimeter/submillimeter Array (ALMA) in early 2023 March. This work focuses on \ce{CH3OH} measurements from both ALMA and JWST as well as \ce{H2O} measurements from JWST. Radiative transfer modeling of \ce{CH3OH} and \ce{H2O} was performed to investigate spatial variations in rotational temperature, column density, and production rates, as well as a comparison of derived values between the two telescopes. Most of the spatial distributions of the modeled values are centrally peaked, and the modeled values from JWST are all within the error bars of the average values from ALMA. C/2022 E3 (ZTF) also displays an enhancement in modeled rotational temperature in the anti-Sunward direction that is shown to be statistically significant. Based on non-LTE radiative transfer modeling, the declining \ce{H2O} rotational temperatures as a function of nucleocentric distance observed by JWST can be explained primarily as a result of rotational line cooling. The values derived in this work are in general agreement with single-dish millimeter-wave observations. - oai:arXiv.org:2601.11767v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Solar twins in Gaia DR3 GSP-Spec I. Building a large catalog of Solar twins with ages + https://arxiv.org/abs/2601.15387 + arXiv:2601.15387v1 Announce Type: new +Abstract: [Abbreviated] Context. Solar twins, stars whose stellar parameters (Teff, log g, and [M/H]) are very close to the Solar ones, offer a unique opportunity to investigate Galactic archaeology with very high accuracy and precision. However, most previous catalogs of Solar twins contain only a small number of objects (typically a few tens), and their selection functions are poorly characterized. Aims. We aim at building a large catalog of Solar twins from Gaia DR3 GSP-Spec, providing model-driven, rather than data-driven, stellar parameters including ages, together with a well-characterized selection function. Methods. Using stellar parameters from the Gaia DR3 GSP-Spec catalog, we selected Solar-twin candidates whose parameters lie within +- 200 K in Teff, +- 0.2 in log g, and +- 0.1 dex in [M/H] of the Solar values. Candidates unlikely to be genuine Solar twins were removed using Gaia flags and photometric constraints. We determined accurate ages for individual twins with a Bayesian isochrone-projection method, considering three combinations of parameters: Teff, [M/H], and either log g, M_G, or M_Ks. We also constructed a mock catalog to characterize the selection function. Results. Our final GSP-Spec Solar-twin catalog contains 6,594 stars. The mock catalog consisting of 75,588 artificial twins well reproduces the main characteristics of the observed catalog, especially for ages determined with M_G or M_Ks. To demonstrate the usefulness of our catalog, we compared chemical abundances [X/Fe] with age. We statistically confirmed the age--[X/Fe] relations for several species (e.g., Al, Si, Ca, and Y), demonstrating that trends previously identified in small but very high-precision samples persist in a much larger, independent sample. Conclusions. Our study bridges small high-precision Solar-twin samples and large data-driven ones, enabling demographic studies of Solar twins. + oai:arXiv.org:2601.15387v1 + astro-ph.SR + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - K. D. Foster, M. A. Cordiner, Nathan X. Roth, S. N. Milam, A. J. Remijan, N. Biver, J. Boissier, J. Crovisier, Y. -J. Kuan, D. C. Lis + Daisuke Taniguchi, Patrick de Laverny, Alejandra Recio-Blanco, Takuji Tsujimoto, Pedro A. Palicio - Einstein Probe discovery of EP J171159.4-333253: an eclipsing neutron star low-mass X-ray binary with clocked bursts - https://arxiv.org/abs/2601.11784 - arXiv:2601.11784v1 Announce Type: new -Abstract: EP J171159.4-333253 is a new neutron-star low-mass X-ray binary discovered in outburst by the Einstein Probe (EP) on 2025 June 23, exhibiting clocked type-I X-ray bursts, eclipses and dips. In this paper, we report on the results of the X-ray spectral and timing analyses for EP J171159.4-333253 using data collected by EP and NuSTAR during the first 21 days of the outburst. The X-ray burst recurrence time can be characterized over a subset of nine bursts spanning 1.6 days around the NuSTAR observation, and the result is $t_{\rm rec}=8196 \pm 177\,$s with indications of a possible decreasing trend. From the X-ray eclipse events, the binary orbital period and the eclipse duration are estimated to be $P_{\rm orb}=6.48301 \pm 0.00003\,$hr and $D_{\star,X} = 1245.5^{+6.9}_{-6.5}\,$s, respectively. These enable an estimate of the mass and radius of the companion star and the binary inclination, which are $M_2\approx0.6-0.8\,M_\odot$, $R_2\approx0.7-0.8\,R_\odot$ and $i\approx73-75^\circ$, respectively. We also report on joint ULTRACAM and EP observations on 2025 July 21--22, detecting the source optical counterpart and covering an eclipse in both X-ray and optical bands. The optical eclipse is wavelength-dependent and broader than in X-rays, indicating that part of the optical emission arises from an extended region in the accretion flow. Despite a moderate variation in the source flux, the properties of the persistent X-ray emission are typical of a hard spectral state. We further evaluated the ratio of the accretion energy to the thermonuclear energy to be 120--130, implying helium bursts with the accreted hydrogen being depleted in-between bursts. - oai:arXiv.org:2601.11784v1 + Dynamic shocks powered by a wide, relativistic, super-Eddington outflow launched by an accreting neutron star in the mid-20th century + https://arxiv.org/abs/2601.15400 + arXiv:2601.15400v1 Announce Type: new +Abstract: Accreting systems can launch powerful outflows which interact with the surrounding medium. We combine new radio observations of the accreting neutron star X-ray binary (XRB) Circinus X-1 (Cir X-1) with archival radio observations going back 24 years. The $\sim3$ pc scale wide-angle radio and X-ray emitting caps found around Cir X-1 are identified as synchrotron emitting shocks with significant proper motion and morphological evolution on decade timescales. Proper motion measurements of the shocks reveal they are mildly relativistic and decelerating, with apparent velocity of $0.14c\pm0.03c$ at a propagation distance of 2 pc. We demonstrate that these shocks are likely powered by a hidden relativistic ($\gtrsim0.3c$) wide-angle conical outflow launched in $1972\pm3$, in stark contrast to known structures around other XRBs formed by collimated jets over 1000s of years. The minimum time-averaged power of the outflow required to produce the observed synchrotron emission is $\sim0.1L_\text{Edd}$, while the time-averaged power required for the kinetic energy of the shocks is $\sim40 \left(\frac{n}{10^{-2} \text{cm}^{-3}}\right)L_\text{Edd}$, where $n$ is the average ambient medium number density. This reveals the outflow powering the shocks is likely significantly super-Eddington. We measure significant linear polarisation up to $52\pm6\%$ in the shocks demonstrating the presence of an ordered magnetic field of strength $\sim200~\mu\text{G}$. We show that the shocks are potential PeVatrons, capable of accelerating electrons to $\sim0.7~\text{PeV}$ and protons to $\sim20~\text{PeV}$, and we estimate the injection and energetic efficiencies of electron acceleration in the shocks. Finally, we predict that next generation gamma-ray facilities may be able to detect hadronic signatures from the shocks. + oai:arXiv.org:2601.15400v1 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Y. L. Wang, F. Coti Zelati, E. Parent, A. Marino, N. Rea, V. S. Dhillon, J. Blanco-Pozo, I. Ribas, S. P. Littlefair, Z. H. Yang, G. B. Zhang, S. Guillot, K. R. Ni, J. H. Wu, A. Patruno, Y. Cavecchi, G. Illiano, A. Papitto, F. Ambrosino, B. F. Liu, H. Q. Cheng, H. Feng, J. W. Hu, C. C. Jin, H. Sun, L. Tao, Y. J. Xu, H. N. Yang, W. Yuan, Q. C. Zhao + F. J. Cowie, R. P. Fender, I. Heywood, F. Carotenuto, J. H. Matthews, B. Reville, L. Olivera-Nieto, A. J. Cooper, A. K. Hughes, K. Savard, P. A. Woudt, J. van den Eijnden, N. Grollimund, P. Saikia - Increased and Varied Radiation during the Sun's Encounters with Cold Clouds in the last 10 million years - https://arxiv.org/abs/2601.11785 - arXiv:2601.11785v1 Announce Type: new -Abstract: Recent research raises the possibility that 3 and 7 million years ago, the Sun encountered massive clouds that shrank the heliosphere--the solar cocoon protecting our solar system--exposing Earth to its interstellar environment, in agreement with geological evidence from 60Fe and 244Pu isotopes. Here we show that during such encounters Earth was exposed to increased radiation in the form of high-energy particles. During periods of Earth's immersion in the heliosphere, it received particle radiation that we name Heliospheric Energetic Particles (HEPs). The intensity of < 10 MeV protons was at least an order of magnitude more intense than today's most extreme solar energetic particle (SEP) events. SEPs today last minutes to hours, but HEP exposure then lasted for extensive periods of several months, making it a prolonged external driver. During Earth's excursion outside the heliosphere, it was exposed to a galactic cosmic ray radiation with the intensity of < 1 GeV protons at least an order of magnitude more intense than today. Therefore, the space surrounding Earth was permeated by a variable high-energy radiation. We discuss the implications for Earth's climate and biodiversity. - oai:arXiv.org:2601.11785v1 - astro-ph.EP + The age sequence of young clusters in Perseus: Estimating ages from mass distributions + https://arxiv.org/abs/2601.15413 + arXiv:2601.15413v1 Announce Type: new +Abstract: Establishing ages for young clusters is key for properly tracking the star formation history of a region. In this paper we investigate a new approach to estimating ages for young populations, based on the well-founded assumption that the initial mass function is the same throughout a star forming cloud. We trial this method for six young clusters in the Perseus star forming region. For all six clusters, we construct new member samples in a homogeneous way using Gaia DR3. We estimate masses by comparing 2MASS photometry to theoretical isochrones, including Monte Carlo simulations to propagate the errors. We compare the mass distributions of the clusters for a range of plausible ages, looking for a combination of ages that results in indistinguishable mass distributions across the region. We find the best fit for ages of 1 Myr for NGC1333+Autochthe, 2 Myr for IC348, 2-3 Myr for Heleus, 3-4 Myr for Mestor, 4-5 Myr for Electryon+Cynurus, and 5-8 Myr for Alcaeus. All other combinations of ages are ruled out by this criterion. The established age sequence is consistent with the relative ages inferred from disc fractions, and broadly aligns with the age sequence determined in previous studies using isochrone fitting. We suggest that this approach can be a useful complement and cross-check to established methods to estimate ages in young populations. + oai:arXiv.org:2601.15413v1 astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Merav Opher, Joe Giacalone, Abraham Loeb, Evan P. Economo, Alan Cummings, Jennifer Middleton, Catherine Zucker, Jesse A. Miller, Anna Nica, Maria Hatzaki + Tatiana Pavlidou (Limassol), Aleks Scholz (St Andrews), Koraljka Muzic (Lisbon) - Habitable Worlds Observatory's Concept and Technology Maturation: Initial Feasibility and Trade Space Exploration - https://arxiv.org/abs/2601.11803 - arXiv:2601.11803v1 Announce Type: new -Abstract: The Habitable Worlds Observatory is the first telescope ever designed to search for life and will be a powerhouse of discovery across topics in astrophysics. The observatory was the top recommendation of the Astro2020 Decadal Survey for large missions and a new HWO Technology Maturation Project Office was formed in August 2024 to mature the architecture, science and technology. In this paper we review the overall approach taken to mature the mission concept. We show progress on architecture development, integrated modeling, science cases, and technology roadmaps consistent with pre-formulation studies. We discuss plans for instrument studies and international engagement and science engagement including a Community Science and Instrument Team. Finally, we describe the plan forward to the Mission Concept Review. - oai:arXiv.org:2601.11803v1 - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Spin-down changes in PSR B0540-69 induced by a drift of the magnetic axis + https://arxiv.org/abs/2601.15425 + arXiv:2601.15425v1 Announce Type: new +Abstract: The dynamics of the solid crust + magnetic field lines of pulsars is a much debated issue, and remains unsettled after 50 years. Some pieces of evidence have emerged to complete and confirm theoretical calculations and expectations. We discuss in the present work an interpretation of the behavior of the ''Crab Twin'' pulsar PSR B0540-69 in terms of the evolution of the magnetic field/quakes, connecting the behavior of the braking index with the underlying platelet drift and sudden discontinuous rearrangement (fast-slip) and long-term ones (slow-slip events), suggested by analogy with existing theoretical picture observed in the Earth's crust. The relationship of this scenario with permanent torque-changing glitches seen in the Crab and other young pulsars, and a set of similar events in the same object and others is addressed. We conclude that this physical approach is in principle consistent with all these sudden events, and point out future work to clarify the whole picture. + oai:arXiv.org:2601.15425v1 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Lee D. Feinberg, Breann N. Sitarski, Michael W. McElwain, Giada Arney, Caleb Baker, Matthew D. Bolcar, Marie Levine, Alice Liu, Bertrand Mennesson, Aki Roberge, J. Scott Smith, Feng Zhao, John Ziemer + Lucas G. Bar\~ao, J. E. Horvath - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) VII: Optically thick gas with broad CO gaussian local line profiles in the HD 121617 disc - https://arxiv.org/abs/2601.11824 - arXiv:2601.11824v1 Announce Type: new -Abstract: CO gas has been detected in $\sim$20 debris discs. We present ALMA observations of the CO-rich HD 121617 debris disc from the ARKS survey. Using high-resolution Band 7 observations of $^{12}CO \ J=3-2$, we analyse local CO line profiles to investigate optical depth, CO mass, and temperature. Spectra are aligned and stacked in concentric annuli to produce local line profiles. The resulting profiles are Gaussian-shaped and broadened by Keplerian shear. The line profiles are modelled using both a simplified toy model and a RADMC-3D model including projection effects and Keplerian shear. Fitting the RADMC-3D model to the $^{13}$CO data, we find that an optically thick model with a temperature of 38 K and a CO mass of $2 \times 10^{-3}$ M$_{\oplus}$ reproduces the observations. The model reproduces the enhanced emission at orbital azimuths of $\sim \pm45^{\circ}$ and $\pm135^{\circ}$, forming an X-shaped structure in the velocity-integrated intensity map, as well as the broader $^{12}$CO linewidth relative to $^{13}$CO. Scaling the model by the ISM abundance ratio ($\sim$77) also reproduces the $^{12}$CO data, though high optical depths and model assumptions limit mass constraints. We find that azimuthally averaged local line profiles appear Gaussian regardless of optical depth, cautioning against their use for distinguishing optically thin and thick emission. We constrain the mean molecular weight to $12.6_{-1.1}^{+1.3}$, dependent on model assumptions. Our $^{13}$CO results suggest that C$^{18}$O may also be optically thick in CO-rich debris discs and that the mean molecular weight is significantly higher than if H$_2$ were the dominant gas species, suggesting a non-primordial composition. - oai:arXiv.org:2601.11824v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Supernova interactions with aspherical circumstellar material I: calculations of light curves, AB magnitudes, spectra, and polarisation + https://arxiv.org/abs/2601.15428 + arXiv:2601.15428v1 Announce Type: new +Abstract: We present an upgraded detailed numerical calculations of supernova (SN) interactions with significantly aspherical circumstellar matter (CSM), primarily formed as a disc or bipolar lobes. The circumstellar disc can arise as a result of, for example, mass transfer in a binary, while bipolar lobes can be the result of a violent pre-explosive ejection of matter, similar to the iconic cases of luminous blue variable stars (LBVs). We numerically simulate the radiation-hydrodynamic (RHD) behaviour of interaction processes using a 2D cylindrical version of the RHD code CASTRO. We then calculate light curves, spectral patterns, and polarisation profiles, all up to a relatively long time of two years after an SN shock breakout and from different directions, using the multidimensional Monte Carlo radiation transfer (MC-RT) codes SEDONA and SIROCCO. We calculated a total of five models for the two aforementioned configurations of the surrounding CSM, for stratified density levels, comparing the simulated hydrodynamic behaviour and differences in their observable properties. RHD models exhibit similar behaviour to previous adiabatic models, but with a significantly slower expansion velocity. The calculated light curves show a relatively smooth evolution in SN-disc interaction, and declines and brightening in SN-lobes interaction. Comparing models with real events with a presumed similar physical process provides guidance for selecting a more accurate CSM configuration when simulating real situations. + oai:arXiv.org:2601.15428v1 + astro-ph.SR + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 10.1051/0004-6361/202556566 - A. Brennan, L. Matr\`a, S. Mac Manamon, S. Marino, G. Cataldi, A. M. Hughes, P. Weber, Y. Han, J. P. Marshall, B. Zawadzki, P. Luppe, A. A. Sefilian, A. Mo\'or, M. A. MacGregor, J. B. Lovell, A. K\'osp\'al, M. Bonduelle, E. Mansell, M. C. Wyatt, T. D. Pearce, J. M. Carpenter, D. J. Wilner, C. del Burgo, S. P\'erez, Th. Henning, J. Milli, E. Chiang + http://creativecommons.org/publicdomain/zero/1.0/ + Petr Kurf\"urst, Georgi Bless, Jakub Fi\v{s}\'ak, Filip Holoubek, Ji\v{r}\'i Krti\v{c}ka, Brankica Kub\'atov\'a, Ji\v{r}\'i Kub\'at, Michal Zaja\v{c}ek - On the role of gravity, turbulence, and the magnetic field in angular momentum transfer within molecular clouds - https://arxiv.org/abs/2601.11830 - arXiv:2601.11830v1 Announce Type: new -Abstract: Observations of molecular structures on scales of $\sim 0.1-50$ pc show that the specific angular momentum ($j$) scales with radius ($R$) as $j\sim R^{3/2}$. We study the effects of turbulence, gravity, and the magnetic field in shaping this scaling, by measuring clump size and specific angular momentum in three SPH simulations of the formation of giant molecular clouds, progressively adding these three ingredients. In each simulation, we define ``full'' and ``reduced'' clump samples, the latter restricted to aspect ratios $A<3$. We find that, in the non-magnetic runs, elongated clumps deviate the most from the \jR\ relation, which is best reproduced by the reduced sample in the gravity+turbulence run. In the purely hydrodynamic case, no dense elongated structures form, suggesting that turbulence alone is insufficient to generate dense filaments, although clumps have $j$ magnitudes consistent with observations. In the gravity+turbulence+magnetic field run, most of the clumps are filamentary, yet the full sample appears to follow the observed \jR\ relation. This result, rather than being a real trend, could be the combination of the increase in $j$ by the filamentary geometry, and its reduction by turbulence inhibition by the magnetic field. Finally, we measure the gravitational, magnetic, pressure-gradient, and hydrodynamic torques (which involve turbulent viscosity) in our clump samples. We find that, in magnitude, the hydrodynamic torques tend to be larger than the rest. This result is consistent with our previous work, where we proposed that gravity drives cloud formation and contraction, while turbulence redistributes angular momentum through fluid-parcel exchanges. - oai:arXiv.org:2601.11830v1 + The role of gas stripping in the quenching of satellite galaxies using SHARK v2.0 + https://arxiv.org/abs/2601.15435 + arXiv:2601.15435v1 Announce Type: new +Abstract: Observational studies have made substantial progress in characterizing quenching as a function of stellar mass and environment, but they are often limited in their ability to constrain quenching timescales and to determine the dominant environmental process responsible for the shutting down of star formation. To address this, we combine recent Sloan Digital Sky Survey (SDSS) observations with the SHARK v2.0 semi-analytic model to study the quenching of satellite galaxies in groups and clusters. We generate mock SDSS-like observations to calibrate the hot halo and cold interstellar medium (ISM) gas stripping prescriptions against observed satellite quenched fractions, finding that the previously adopted stripping prescriptions in SHARK v2.0 are too aggressive and overestimate the quenched fraction of satellite galaxies. Reducing the efficiency of both hot and cold gas stripping yields excellent agreement with observations for low- and intermediate-mass satellite galaxies. We use the calibrated model to investigate quenching timescales and find that satellites quench more quickly in clusters compared to groups, with timescales that generally decrease with increasing stellar mass. The long (>2 Gyr) timescales we measure favour hot halo gas removal as the dominant driver of satellite quenching. + oai:arXiv.org:2601.15435v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Griselda Arroyo-Chavez, Enrique Vazquez-Semadeni, James Wurster + Megan K. Oxland, Mat\'ias Bravo, Laura C. Parker, Claudia del P. Lagos - Template-free search for gravitational wave events using coincident anomaly detection - https://arxiv.org/abs/2601.11842 - arXiv:2601.11842v1 Announce Type: new -Abstract: Gravitational-wave (GW) observatories have used template-based search to detect hundreds of compact binary coalescences (CBCs). However, template-based search cannot detect astrophysical sources that lack accurate waveform models, including core-collapse supernovae, neutron star glitches, and cosmic strings. Here, we present a novel approach for template-free search using coincident anomaly detection (CoAD). CoAD requires neither labeled training examples nor background-only training sets, instead exploiting the coincidence of events across spatially separated detectors as the training loss itself: two neural networks independently analyze data from each detector and are trained to maximize coincident predictions. Additionally, we show that integrated gradient analysis can localize GW signals from the neural-network weights, providing a path toward data-driven template construction of unmodeled sources, and further improving precision by frequency matching. Using the CodaBench dataset of real LIGO backgrounds with injected simulated CBCs and sine-Gaussian low-frequency bursts, CoAD achieves recall up to 0.91 and 0.85 respectively at a false-alarm rate of one event per year, and achieves recall above 0.5 at signal-to-noise ratios below 10. The fully-unsupervised nature of CoAD makes it especially well-suited for next-generation detectors with greater sensitivity and associated increases in GW event rates. - oai:arXiv.org:2601.11842v1 - astro-ph.IM - gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 + Perihelion Asymmetry in the Water Production Rate of the Interstellar Object 3I/ATLAS + https://arxiv.org/abs/2601.15443 + arXiv:2601.15443v1 Announce Type: new +Abstract: 3I/ATLAS is an interstellar object whose activity provides critical insights into its composition and origin. However, due to its orbital geometry, the object is too close to the Sun near perihelion to be observed from the ground, and space-based measurements are therefore required. Here we characterize the water production rate of 3I/ATLAS using SOHO/SWAN Lyman-$\alpha$ observations from 2025 November to December (heliocentric distances 1.4 to 2.2 au) with 3D Monte Carlo modeling. We report a peak post-perihelion water production rate of $Q_{\mathrm{H_2O}} \approx 4 \times 10^{28}$ mol s$^{-1}$, corresponding to a minimum active fraction of $\sim$30\% (assuming a maximum nucleus radius of 2.8 km). Comparison of our post-perihelion measurements with published pre-perihelion results reveals a heliocentric asymmetry, with an $r_h^{-5.9 \pm 0.8}$ scaling for the inbound rise, followed by a shallower $r_h^{-3.3 \pm 0.3}$ scaling during the outbound decline, where $r_h$ is heliocentric distance. The post-perihelion behavior indicates that the water production of 3I/ATLAS was driven primarily by the varying solar insolation acting on a stable active area. Combined with other evidence, including comparison with the hyperactive comet 103P/Hartley 2, our findings suggest that its water production is likely dominated by a distributed source of icy grains. Furthermore, it displayed remarkable stability in the activity with no signs of outbursts or rapid depletion of water production. + oai:arXiv.org:2601.15443v1 + astro-ph.EP + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daniel Ratner + Hanjie Tan (Planetary Environmental and Astrobiological Research Laboratory), Xiaoran Yan (National Research Council, Institute of Applied Physics "Nello Carrara"), Jian-Yang Li (Planetary Environmental and Astrobiological Research Laboratory, Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, China) - Quiet, but not silent. The X-ray activity of the Maunder minimum star HD 166620 - https://arxiv.org/abs/2601.11853 - arXiv:2601.11853v1 Announce Type: new -Abstract: As the only known unambiguous star in a Maunder minimum-like chromospheric activity state, the properties of HD 166620 can provide valuable insight into the behaviour of the Sun during the historic extended low-states of its activity cycle. The coronal X-ray activity of HD 166620 has so far only been probed with a ROSAT/HRI observation in 1996, near the chromospheric activity maximum before the star entered its grand minimum around 2004. We conducted a deep {\it XMM-Newton} observation of HD 166620 during its chromospheric Ca II H&K activity grand minimum to achieve a better understanding of its magnetic activity. We detected HD 166620 with an X-ray luminosity of ${{\rm log}\,L_{\rm X}\,\rm{(erg\,s^{-1})}=26.56^{+0.10}_{-0.12}}$, corresponding to ${{\rm log}\,(L_{\rm X}/L_{\rm bol}) = -6.58^{+0.10}_{-0.12}}$ and an X-ray surface flux of log Fx (erg/cm^2/s) = 3.97+0.10-0.12. With respect to the earlier ROSAT observation, the X-ray brightness of HD 166620 has decreased by a factor of 2.5 during its Maunder minimum-like state. To place its X-ray properties into context, we constructed an X-ray sample of late-type stars within 10 pc of the Sun. The activity of HD 166620 is below the levels of all other K dwarfs in the 10 pc sample. The corona of HD 166620 during its grand minimum emits at the level of the solar background corona, which implies that it has no large active magnetic structures. Along with long-term Ca II H&K monitoring of HD 166620, this result provides evidence that the solar activity during the Maunder minimum was not reduced significantly below the levels seen during its present-day cycle minima. The similar X-ray surface flux of HD 166620 and the modern quiet Sun, and also their Rossby number near the critical value of spin-down models, suggest a connection between the regime of weakened magnetic braking and the occurrence of Maunder minimum states. - oai:arXiv.org:2601.11853v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.1051/0004-6361/202558202 - M. M. Bennedik, B. Stelzer, H. Isaacson, A. Binks, M. Caramazza, F. Haberl - - - Data Mining-Based Cislunar Escape-Family Analysis in The Multi-Body Models - https://arxiv.org/abs/2601.11881 - arXiv:2601.11881v1 Announce Type: new -Abstract: Escape trajectories from the Earth-Moon system play an important role in interplanetary transfer. This paper focuses on the escape trajectories from a 167 km circular Earth orbit in the Earth-Moon planar circular three-body problem and the Sun-Earth/Moon planar bicircular four-body problem and is denoted to providing a comprehensive analysis on these escape trajectories. To achieve these purposes, the global maps of escape trajectories are constructed, and escape trajectories with one lunar gravity assist are pre-filtered. Then, an effective method to identification escape families is proposed based on dynamical analysis and data mining techniques. Once the escape families are identified, the corresponding characteristics are analyzed to provide insights into the construction of escape trajectories. Based on these escape families, the effects of the solar gravity perturbation on the number of escape trajectories, the emergence and disappearance of escape families, variation in generalized energy, and transfer characteristics are further summarized, providing insights into the model selection in the escape trajectory construction. This paper establishes an analysis methodology of escape trajectories from a perspective of escape families, deepening the understanding of escape dynamics. - oai:arXiv.org:2601.11881v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + The long quest for vacuum birefringence in magnetars: 1E 1547.0-5408 and the elusive smoking gun + https://arxiv.org/abs/2601.15452 + arXiv:2601.15452v1 Announce Type: new +Abstract: Magnetars are now known to be among the most strongly polarized celestial sources in X-rays. Here we report on the $500\,\mathrm{ks}$ observation of the magnetar 1E 1547.0-5408 performed by the Imaging X-ray Polarimetry Explorer (IXPE) in March 2025. The IXPE spectrum is well reproduced by a single thermal component with blackbody temperature $kT_\mathrm{BB}\sim 0.67\,\mathrm{keV}$ and emission radius $R_\mathrm{BB}\sim 1.2\,\mathrm{km}$. The source exhibits a high linear polarization degree in the $2$--$6\,\mathrm{keV}$ band ($\mathrm{PD}=47.7\pm2.9\%$) with polarization angle $\mathrm{PA}=75^\circ.8 \pm 1.^\circ8$, measured West of celestial North. While $\mathrm{PA}$ does not appear to vary with energy, there is some evidence (at the $1\sigma$ confidence level) of a minimum in $\mathrm{PD}$ between $3$ and $4\,\mathrm{keV}$, compatible with what is expected by partial mode conversion at the vacuum resonance in a magnetized atmosphere. Phase-resolved spectral and polarimetric analyses reveal that X-ray thermal radiation likely originates from a single, fairly small hot spot with a non-uniform temperature distribution. Fitting the phase-dependent $\mathrm{PA}$ measured by IXPE with a rotating vector model (RVM) constrains the source geometry and indicates that both the dipole axis and line-of-sight are misaligned with respect to the spin axis. Under these conditions, the high polarization of the source cannot be regarded as compelling evidence for the presence of vacuum birefringence in the star magnetosphere. Nevertheless, the fact that the RVM successfully reproduces the modulation of the X-ray polarization angle and the behavior of $\mathrm{PD}$ with the energy hint once more to the presence of QED effects in magnetars. + oai:arXiv.org:2601.15452v1 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Shuyue Fu, Di Wu, Shengping Gong, Peng Shi + http://creativecommons.org/licenses/by/4.0/ + Roberto Taverna, Roberto Turolla, Lorenzo Marra, Ruth M. E. Kelly, Alice Borghese, Gian Luca Israel, Sandro Mereghetti, Silvia Zane, Michela Rigoselli - Prediction of Multi-Wavelength Afterglows Associated with FRB 20200120E and FRB 20201124A - https://arxiv.org/abs/2601.11887 - arXiv:2601.11887v1 Announce Type: new -Abstract: Fast radio bursts (FRBs) are mysterious radio transients with uncertain origins and environments. Recent studies suggest that some active FRBs may originate from compact objects in binary systems. In this work, we develop a unified theoretical framework to model the multi-wavelength afterglows of FRBs resided in binary systems and apply it to two representative repeaters, FRB 20200120E and FRB 20201124A. By solving the dynamics and radiation processes of FRB ejecta interacting with the surrounding medium, we compute afterglow light curves in the radio, optical, and X-ray bands. Our results show that radio afterglows offer the best prospects for detection, with their brightness highly sensitive to ejecta kinetic energy and ambient density. Future high-sensitivity radio telescopes, such as the Square Kilometre Array (SKA), could detect these signals. Optical afterglows, though short-lived and challenging to observe, may be significantly enhanced in dense environments, potentially making them detectable with facilities like the Large Synoptic Survey Telescope (LSST). In contrast, X-ray afterglows are predicted to be too faint for detection with current instruments. Our study highlights the potential of multi-wavelength afterglows as probes of FRB progenitors and their surrounding environments, offering crucial insights into the nature of these mysterious transients. - oai:arXiv.org:2601.11887v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Constraining nonminimal f(T) gravity from Primordial Nucleosynthesis to Late-Universe observations + https://arxiv.org/abs/2601.15460 + arXiv:2601.15460v1 Announce Type: new +Abstract: We present a multi-epoch test of f(T) gravity with nonminimal torsion-matter coupling, combining early- and late-Universe observations. At the MeV scale, Big-Bang Nucleosynthesis constrains the fractional variation of the weak freeze-out temperature, |{\delta}{\tau}_f/{\tau}_f|, thereby mapping light-element abundances into limits on deviations from the standard expansion history. At low redshift, we confront the model with type Ia supernovae, baryon acoustic oscillations, and cosmic-chronometer data, which respectively probe distances, the late-time standard ruler, and the Hubble rate. Independent analyses highlight the complementary roles of each dataset, while a joint SNe Ia + BAO + CC fit breaks degeneracies and yields the tightest combined bounds. As an illustration, we examine two representative torsion-modified gravity scenarios: BBN strongly limits large departures from standard cosmology, whereas late-time probes remain compatible with a near-{\Lambda}CDM background. This unified approach demonstrates the power of linking early-Universe nuclear physics with precision cosmological observables in assessing torsional extensions of gravity. + oai:arXiv.org:2601.15460v1 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1016/j.rinp.2026.108587 + Results in Physics, 81 (2026) 108587 + Yahia Al-Omar, Majida Nahili, Nidal Chamoun + + + Two Fluid Quantum Bouncing Cosmology I: Theoretical Model + https://arxiv.org/abs/2601.15542 + arXiv:2601.15542v1 Announce Type: new +Abstract: Bouncing cosmologies offer an alternative to inflation by resolving the initial + singularity through a contracting phase followed by a bounce into expansion. In many + such models, the contracting phase is dominated by a single matter component, + typically pressureless dust, which leads to an almost scale-invariant spectrum of + scalar cosmological perturbations with a slight blue tilt, so that generating the + observed red-tilted spectrum within this framework was challenging. In this work, we + consider a more realistic scenario in which the contracting phase includes both + matter and radiation, as required on physical grounds. We show that the presence of + radiation can naturally induce a red tilt in the spectrum of curvature perturbations + seeded by quantum vacuum fluctuations in the remote past of the contraction. Since + the perturbations of the two fluids are coupled via gravity, vacuum initial + conditions must be carefully defined. We demonstrate that, without fine-tuning, the + resulting entropy perturbations are subdominant with respect to curvature + perturbations. This suggests that a minimal two-component bounce model, involving + only ordinary matter and radiation, can connect to the standard expanding cosmology + with observationally viable initial conditions. + oai:arXiv.org:2601.15542v1 + astro-ph.CO + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ke Bian, Can-Min Deng + Sandro D. P. Vitenti, Nelson Pinto-Neto, Patrick Peter, Luiz Felipe Dem\'etrio - Possible Multi-band Afterglows of FRB 20171020A and its Implication - https://arxiv.org/abs/2601.11889 - arXiv:2601.11889v1 Announce Type: new -Abstract: Fast Radio Bursts (FRBs) are millisecond-duration radio transients of mysterious origin, with growing evidence linking at least some of them to magnetars. While FRBs are primarily observed in the radio band, their potential multi-wavelength afterglows remain largely unexplored. We investigate the possible afterglow of FRB 20171020A, a rare nearby and bright FRB localized in a galaxy at only 37 Mpc. Assuming that this source produces a future bright burst, we model the expected afterglow emission in the radio, optical, and X-ray bands under both uniform and wind-like ambient media, within the framework of the magnetar model. Our results show that the optical afterglow is the most promising for detection, but it fades rapidly and requires follow-up within a few hundred seconds post-burst. The radio afterglow may be detectable under favorable conditions in a dense stellar wind, whereas the X-ray counterpart is too faint for current telescopes. These findings suggest that rapid optical follow-up offers the best opportunity to detect the afterglow of the next bright burst from FRB 20171020A, providing unique insights into the progenitor and its environment. To assess observational feasibility, we estimate the event rate of nearby FRBs with sufficient energy to power detectable afterglows, finding a rate of $\sim$0.3 per year for CHIME surveys. Although this rate is low and the optical detection timescale is short, coordinated fast-response strategies using global telescope networks could significantly improve the chance of success. As more nearby FRBs are discovered, multi-wavelength observations will be essential in unveiling the physical nature of these enigmatic events. - oai:arXiv.org:2601.11889v1 + Source identification for the Swift-BAT 150-month hard X-ray catalog using soft X-ray observations + https://arxiv.org/abs/2601.15577 + arXiv:2601.15577v1 Announce Type: new +Abstract: We present a comprehensive catalog of 251 potential counterparts for 250 unassociated hard X-ray sources detected in the Swift Burst Alert Telescope (BAT) 150-month hard X-ray survey. Over 150 months of observation, BAT has detected 2339 sources in the 15-150 keV energy range. Among these, 344 do not have a previously identified low-energy counterpart. Our study focuses on the analysis of soft X-ray observations at energies below 10 keV, spatially overlapping with these new Swift-BAT hard X-ray sources. Such observations were taken with Chandra, Swift-XRT, eROSITA, and XMM-Newton. Within the sample of 251 potential counterparts, 94 (37 percent) are identified as active galactic nuclei and 58 (23 percent) as galaxies. The remaining 99 sources (40 percent) include pulsars, cataclysmic variables, and unclassified soft X-ray counterparts in the 0.5-10 keV band. Redshift information is available for 139 out of the 251 sources, and its distribution is in close agreement with the redshift distribution of previous BAT catalogs. We also present the results of a small optical spectroscopy campaign of 9 out of 58 galaxies. The majority of these are classified as Seyfert 2 galaxies at redshifts slightly larger than the median of the BAT AGN sample. + oai:arXiv.org:2601.15577v1 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ke Bian, Can-Min Deng + K. Imam, N. Torres-Alba, S. Marchesi, M. Ajello, S. Joffre, I. Cox, A. Pizzetti, X. Zhao, A. Segreto, A. Banerjee, I. Pal, V. E. Gianolli, D. Stern - Evidence for 1.01 s Pulsations of the Central Compact Object in the Supernova Remnant RCW 103 with ASCA, XMM-Newton, and NuSTAR - https://arxiv.org/abs/2601.11917 - arXiv:2601.11917v1 Announce Type: new -Abstract: The neutron-star X-ray source 1E 161348-5055, associated with the supernova remnant RCW 103, exhibits clear intensity variations with a period of 6.67 hr. To clarify the nature of this object and its long periodicity, detailed timing studies were applied to its archival X-ray data, taken with ASCA (in 1993), XMM-Newton (in 2001, 2005, and 2016), and NuSTAR (2016 and 2017). It was assumed that the 6.67 hr period arises due to the beat between the rotation and free precession periods of the star that is slightly aspherical. By removing timing perturbations to be caused by this long periodicity, the six data sets consistently yielded evidence for pulsations at periods of P~1.01 s, to be interpreted as the objects' spin period, although the optimum energy range differed among the data sets. The measured six periods accurately line up on a linear spin-down trend of dP/dt = 1.097x 10^{-12} s/s. The object is implied to have a characteristic age of 14.7 kyr, a spin-down luminosity of 4.2x10^{34} erg/s, which is insufficient to power the X-ray luminosity, a dipole magnetic field of ~4.6x10^{13} G, and a toroidal field of ~7 x10^{15} G. Its similarity and dissimilarity to magnetars are discussed. An emission geometry, which crudely explain these results, is presented. - oai:arXiv.org:2601.11917v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Mapping dark matter and the emergence of large-scale structure + https://arxiv.org/abs/2601.15583 + arXiv:2601.15583v1 Announce Type: new +Abstract: We discuss a potential survey to map dark matter and the emergence of large-scale structure to redshift z ~ 1.5 (baseline) or z~3.5 (with near-IR extension) using a massively multiplexed spectrograph on a 10m-class telescope, such as the proposed Widefield Spectroscopic Telescope. + oai:arXiv.org:2601.15583v1 + astro-ph.CO + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Kazuo Makishima, Nagomi Uchida, Teruaki Enoto + http://creativecommons.org/licenses/by/4.0/ + Jon Loveday, Jochen Liske, Ivan K. Baldry, Simon P. Driver, Aaron Robotham, Sabine Bellstedt, Luke Davies, Trystan Lambert - Captured are circularized: A relativistic treatment of extreme mass ratio inspirals crossing accretion disks - https://arxiv.org/abs/2601.11925 - arXiv:2601.11925v1 Announce Type: new -Abstract: A small body orbiting around an accreting massive object and periodically crossing its accretion disk is a common configuration in astrophysics. In this work, we investigate the secular evolution of extreme mass-ratio inspirals (EMRIs), in which a stellar-mass object (SMO), e.g., a star or a stellar-mass black hole (sBH), collides with the accretion disk of a central supermassive black hole (SMBH), within a fully relativistic framework. We find (1) the disk always tends to align the SMO no matter what the initial orbital inclination $\iota$ relative to the disk is, (2) the final orbital eccentricity of the SMO captured by the disk is always low though the orbital eccentricity may temporarily grow when the orbital inclination $\iota$ is large and the SMO is an sBH, and (3) via collisions with the accretion disk only, only a small fraction of sBHs that are initially close to the SMBH and close to the disk can be captured by the disk within typical disk lifetime of active galactic nuclei. Two-body scatterings between SMOs in the nuclear stellar cluster play an essential role in randomly kicking sBHs towards the disk and boosting the capture rate. - oai:arXiv.org:2601.11925v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Multi-band Reconstruction of Sixteen Gravitational Lens Systems using PISCO data + https://arxiv.org/abs/2601.15585 + arXiv:2601.15585v1 Announce Type: new +Abstract: Next-generation surveys such as the Euclid survey, the Legacy Survey of Space and Time (LSST), and the China Space Station Telescope (CSST) survey are expected to discover ~10^5 galaxy-galaxy scale strong gravitational lenses. This motivates the development of scalable and robust lens modeling approaches that can efficiently and reliably learn from wide-field survey datasets before high-resolution follow-up. We design a scalable, Bayesian, Lenstronomy-based pipeline and apply it to a sample of sixteen lens candidates observed with the Parallel Imager for Southern Cosmology Observations (PISCO) on the Magellan telescope. PISCO provides four-band imaging (z, i, r, g) with colours, depth and seeing conditions comparable to LSST. To fully exploit the constraining power of this dataset, our pipeline performs simultaneous multi-band modeling, using a common mass profile across all four bands while allowing independent light profiles in each. This approach leverages color information to provide joint constraints on the lens mass and yields reduced uncertainties compared to single-band analyses. Fifteen out of sixteen PISCO lens candidates are successfully recovered with interpretable lensing configurations, including DESJ0533-2536, the first reported hyperbolic-umbilic galaxy-galaxy scale strong lensing candidate. We further assess how much model complexity can be reliably constrained given the resolution and seeing of PISCO-like data. Overall, our results demonstrate that scalable, multi-band lens modeling of ground-based data can extract meaningful constraints on mass and source morphology, providing a practical pathway to maximize the scientific return from large samples in upcoming surveys. + oai:arXiv.org:2601.15585v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yuhe Zeng, Zhen Pan + 10.1093/mnras/stag153 + Huimin Qu, Daniel J. Ballard, Geraint F. Lewis, Karl Glazebrook, Antony Stark, Sarah M. Sweet, Colin Jacobs, Kim-Vy Tran, Brian Stalder, Tania M. Barone, Tucker Jones, Keerthi Vasan G. C., Thomas E. Collett, Glenn G. Kacprzak, Dorota Bayer - A Dynamo Confinement Scenario for the Solar Tachocline and its Implications for Spin-down in the Radiative Spreading Regime - https://arxiv.org/abs/2601.11943 - arXiv:2601.11943v1 Announce Type: new -Abstract: At the base of the Sun's convective zone, a narrow shear layer called the tachocline separates strong latitudinal differential rotation above from nearly rigid rotation in the radiative zone below. The observed thinness of the tachocline is a long-standing dynamical puzzle because the tachocline should have spread significantly due to inward-burrowing meridional circulation, also called "radiative spreading." We recently presented the first pair of global simulations to reveal a statistically stationary tachocline confined against radiative spreading by the Maxwell stresses from the nonaxisymmetric modes of a dynamo, which penetrated into and below the tachocline through a novel magnetic skin effect. In the work presented here, we systematically examine how this "dynamo confinement scenario" works against radiative spreading in a suite of simulations as the governing parameters trend in the direction of the true solar regime. We find that as the stable stratification of the radiative zone is made progressively stronger, the dynamo cycles get longer, the magnetic field consequently penetrates deeper due to the skin effect, and the tachocline becomes more confined. Furthermore, these results have interesting consequences for solar spin-down. In all of our radiatively spreading simulations, the tachocline region spins down due to the burrowing circulation. Below the tachocline, the Maxwell stresses transmit this spin-down further to rigidify the deeper radiative zone. We thus speculate that, in addition to confining the tachocline, the dynamo may provide a pathway to communicate spin-down from the near-surface layers to the deep interior. - oai:arXiv.org:2601.11943v1 + A compact object with a K type star companion in the solar neighborhood: a wide post common envelope binary with a white dwarf candidate + https://arxiv.org/abs/2601.15619 + arXiv:2601.15619v1 Announce Type: new +Abstract: Post-common envelope binaries (PCEBs) consisting of a white dwarf (WD) plus a main-sequence (MS) star can constrain current prescriptions of common envelope evolution (CEE) and calibrate theoretical models of binary formation and evolution. Most PCEBs studied to date have typical orbital periods of hours to a few days and can be well explained by assuming inefficient CEE to expel the envelope. However, there are currently several systems with relatively wide orbital periods ($>$18 days). To explain these wide PCEBs, additional sources of energy have been suggested to be taken into account. Here, we present the discovery and observational characterization of a compact object ($M\,\geq\,0.58\,\rm M_{\odot}$) with a K-type star companion in the solar neighborhood ($d\sim 112$ pc) and an orbital period of $P_{\rm orb}\sim 14$ days. The compact object binary is likely to be a system consisting of a WD and a barium dwarf. Such a system with an orbital period within the gap between tight and wide binaries provides a test of whether additional energy sources are required to explain its formation. Using binary evolution models, we investigate the evolutionary history of this wide PCEB system and find that the observed properties of this source can be explained without invoking any extra energy source. + oai:arXiv.org:2601.15619v1 astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Loren I. Matilsky, Lydia Korre, Nicholas H. Brummell + Jie Lin, Hailiang Chen, Bojun Wang, Yudong Luo, Wenshi Tang, Bo Huang - Pushchino Multibeam Pulsar Search. IX. Detection of a minute-long transient on the LPA antenna - https://arxiv.org/abs/2601.11950 - arXiv:2601.11950v1 Announce Type: new -Abstract: A transient (LPA J0108+13) with repeated bursts was detected on the Large Phased Array (LPA) radio telescope at a central frequency of 110.4 MHz in the direction of the radio galaxy 3C 33. The flux density of bursts ranges from tens to hundreds of Jy, and the duration of the bursts is \approx 1^m - 4^m. In daily observations, the total duration of which at the location of the transient exceeds 200 hours in the observation interval 2013-2025, 6 bursts were found. The nature of the source could not be determined. We believe that a new type of transients has been discovered. - oai:arXiv.org:2601.11950v1 + The initial spin matters: the impact of rapid rotation on magnetic-field amplification at merger + https://arxiv.org/abs/2601.15650 + arXiv:2601.15650v1 Announce Type: new +Abstract: A couple of milliseconds after the merger of a binary system of neutron stars can play a fundamental role in amplifying the comparatively low initial magnetic fields into magnetar strengths. The basic mechanism responsible for this amplification is the Kelvin-Helmholtz instability (KHI) and we here report the first systematic study of the impact of rapid rotation on the KHI-amplification process exploiting general-relativistic magnetohydrodynamic simulations at very high-resolutions of $35\,{\rm m}$. Concentrating on four different spinning configurations, we find that aligned, anti-aligned, and mixed (aligned/anti-aligned) spin configurations lead to markedly different growth rates of the electromagnetic (EM) energy, field topologies, and vortex properties when compared to the irrotational case. These differences arise from intrinsic variations in the system dynamics, such as tidal deformation, collision strength, and contact surface area, with the anti-aligned configuration producing the largest vorticity and growth in EM energy. Importantly, while different spin configurations lead to significantly different initial growth rates of the poloidal/toroidal components, all systems converge to a specific topological partition. Our simulations are confined to a short window in time, but the different EM energies produced as a result of spin will imprint the EM emission at merger and provide information on the spinning state at merger. + oai:arXiv.org:2601.15650v1 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - A. M. Anpilogov, S. A. Tyul'bashev + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Harry Ho-Yin Ng, Jin-Liang Jiang, Luciano Rezzolla - Euclid: Early Release Observations -- The extended stellar component of the IC10 dwarf galaxy - https://arxiv.org/abs/2601.11997 - arXiv:2601.11997v1 Announce Type: new -Abstract: We present a detailed analysis of the old, extended stellar component of the Local Group dwarf galaxy IC 10 using deep resolved-star photometry in the VIS and NISP bands of the Euclid Early Release Observations. Leveraging Euclid's unique combination of wide field of view and high spatial resolution, we trace red giant branch (RGB) stars out to $\sim$8 kpc from the galaxy centre, reaching azimuthally-averaged surface brightness levels as faint as $\mu_{HE}\sim$29 mag arcsec$^{-2}$. Our analysis reveals that IC 10's stellar distribution is significantly more extended than previously thought. After correcting for foreground extinction and subtracting contamination from Milky Way stars and background galaxies, we derive a radial stellar density profile from RGB star counts. The profile shows a marked flattening beyond $\sim$5 kpc, and is best fit by a two-component (Sersic + exponential) model, yielding a total stellar mass in old (age $>$1 Gyr) stars of $M_{\star}=(6.7-8.1)\times10^8 M_{\odot}$. The origin of the outer stellar component is unclear. It may be accreted, even possibly associated with the counter-rotating HI gas in the outer regions of IC 10, or it may represent an ancient in-situ stellar halo. We tentatively detect two symmetric stellar overdensities at the edge of our imagery. These roughly align with the direction of IC 10's orbit around M31, suggesting that they may be signatures of tidal stripping. As part of our analysis, we derive a new distance to IC 10 based on the RGB tip, finding $D=762\pm 20$ kpc and the distance modulus is $(m-M)_0=24.41\pm 0.05$. - oai:arXiv.org:2601.11997v1 + K-DRIFT Science Theme: Galactic Cirrus Clouds and Circumgalactic Medium + https://arxiv.org/abs/2601.15665 + arXiv:2601.15665v1 Announce Type: new +Abstract: In this paper, we review the extended halo material and the circumgalactic medium (CGM), including both dust and gas, and discuss promising science cases that could be realized using the KASI Deep Rolling Imaging Fast Telescope (K-DRIFT). Scattered starlight from cirrus clouds in our Galaxy poses one of the major challenges to studying the low surface brightness features of extragalactic sources. Therefore, it is essential to investigate how to discriminate extragalactic sources from the cirrus cloud features. At the same time, interstellar dust clouds themselves are fundamental to understanding dust properties and the interstellar radiation field, both of which are essential for studies of chemical evolution and star formation in our Galaxy. Measuring the reddening of background sources, such as quasars, with K-DRIFT, which benefits from its broad field of view and accurate background subtraction, allows for effective detection of extended dust in galactic halos, the CGM, and intracluster space. Observations of the H-alpha emission lines can be used to identify signatures of star formation activity within galaxies, as well as the environmental effects acting on them. Galactic winds driven by active galactic nuclei and starbursts can be traced through H-alpha emission. Strong ram pressure stripping effectively removes the interstellar medium (ISM) from galaxies. The stripped ISM becomes ionized or dissociated through mixing with the hot intracluster medium (ICM), forming H-alpha tails. The surface brightness of these H-alpha tails correlates not only with the presence of star formation in the tails but also the mixing stage of the stripped ISM and ICM. The H-alpha survey with K-DRIFT will enable the investigation of the evolutionary stages of ram pressure stripped galaxies in cluster environments, as well as the multiphase gas reservoir around galaxies and in the CGM. + oai:arXiv.org:2601.15665v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - F. Annibali (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), A. M. N. Ferguson (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), P. M. Sanchez-Alarcon (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Tenerife, Spain, Universidad de La Laguna, Dpto. Astrof\'i sica, E-38206 La Laguna, Tenerife, Spain), P. Dimauro (Observatorio Nacional, Rua General Jose Cristino, 77-Bairro Imperial de Sao Cristovao, Rio de Janeiro, 20921-400, Brazil, INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), L. K. Hunt (INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy), R. Pascale (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), M. Bellazzini (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), A. Lan\c{c}on (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), P. Jablonka (Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique F\'ed\'erale de Lausanne), J. M. Howell (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), K. Voggel (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), J. -C. Cuillandre (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), Abdurro'uf (Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405, USA), G. Battaglia (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Universidad de La Laguna, Dpto. Astrof\'i sica, E-38206 La Laguna, Tenerife, Spain), L. R. Bedin (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), Michele Cantiello (INAF - Osservatorio Astronomico d'Abruzzo, Via Maggini, 64100, Teramo, Italy), D. Carollo (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), P. -A. Duc (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), S. S. Larsen (Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands), M. Libralato (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), F. R. Marleau (Universit\"at Innsbruck, Institut f\"ur Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria), D. Massari (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), T. Saifollahi (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), C. Tortora (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), M. Urbano (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), M. Gatto (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), I. McDonald (Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK), M. Baes (Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium), J. Rom\'an (Departamento de F\'isica de la Tierra y Astrof\'isica, Universidad Complutense de Madrid, Plaza de las Ciencias 2, E-28040 Madrid, Spain), E. Dalessandro (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), E. Iodice (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), R. Ragusa (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), S. Pearson (DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155, 2200 Copenhagen, Denmark), S. Andreon (INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), N. Auricchio (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), C. Baccigalupi (IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy), M. Baldi (Dipartimento di Fisica e Astronomia, Universit\`a di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), A. Balestra (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), S. Bardelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), P. Battaglia (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), A. Biviano (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy), E. Branchini (Dipartimento di Fisica, Universit\`a di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), M. Brescia (Department of Physics "E. Pancini", University Federico II, Via Cinthia 6, 80126, Napoli, Italy, INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), S. Camera (Dipartimento di Fisica, Universit\`a degli Studi di Torino, Via P. Giuria 1, 10125 Torino, Italy, INFN-Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy, INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese), G. Ca\~nas-Herrera (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK, Leiden Observatory, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands), V. Capobianco (INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese), C. Carbone (INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy), J. Carretero (Centro de Investigaciones Energ\'eticas, Medioambientales y Tecnol\'ogicas, Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra), S. Casas (Institute for Theoretical Particle Physics and Cosmology, Deutsches Zentrum f\"ur Luft- und Raumfahrt e. V), M. Castellano (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), G. Castignani (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Cavuoti (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy, INFN section of Naples, Via Cinthia 6, 80126, Napoli, Italy), A. Cimatti (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), C. Colodro-Conde (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Tenerife, Spain), G. Congedo (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), C. J. Conselice (Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK), L. Conversi (European Space Agency/ESRIN, Largo Galileo Galilei 1, 00044 Frascati, Roma, Italy, ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), Y. Copin (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), F. Courbin (Institut de Ci\`encies del Cosmos, Instituci\'o Catalana de Recerca i Estudis Avan\c{c}ats, Institut de Ciencies de l'Espai), H. M. Courtois (UCB Lyon 1, CNRS/IN2P3, IUF, IP2I Lyon, 4 rue Enrico Fermi, 69622 Villeurbanne, France), M. Cropper (Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK), H. Degaudenzi (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), G. De Lucia (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), H. Dole (Universit\'e Paris-Saclay, CNRS, Institut d'astrophysique spatiale, 91405, Orsay, France), F. Dubath (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), C. A. J. Duncan (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), X. Dupac (ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), S. Escoffier (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), M. Farina (INAF-Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere, 100, 00100 Roma, Italy), R. Farinelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Ferriol (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), F. Finelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy), M. Frailis (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), E. Franceschi (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), M. Fumana (INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy), S. Galeotta (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), K. George (University Observatory, LMU Faculty of Physics, Scheinerstr.~1, 81679 Munich, Germany), B. Gillis (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), C. Giocoli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), J. Gracia-Carpio (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), A. Grazian (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), F. Grupp (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany, Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr.~1, 81679 M\"unchen, Germany), S. V. H. Haugan (Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, 0315 Oslo, Norway), H. Hoekstra (Leiden Observatory, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands), W. Holmes (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA), I. M. Hook (Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK), F. Hormuth (Felix Hormuth Engineering, Goethestr. 17, 69181 Leimen, Germany), A. Hornstrup (Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark, Cosmic Dawn Center), K. Jahnke (Max-Planck-Institut f\"ur Astronomie, K\"onigstuhl 17, 69117 Heidelberg, Germany), M. Jhabvala (NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA), E. Keih\"anen (Department of Physics and Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), S. Kermiche (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), A. Kiessling (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA), B. Kubik (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), M. K\"ummel (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr.~1, 81679 M\"unchen, Germany), M. Kunz (Universit\'e de Gen\`eve, D\'epartement de Physique Th\'eorique and Centre for Astroparticle Physics, 24 quai Ernest-Ansermet, CH-1211 Gen\`eve 4, Switzerland), H. Kurki-Suonio (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland, Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), R. Laureijs (Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands), A. M. C. Le Brun (Laboratoire d'etude de l'Univers et des phenomenes eXtremes, Observatoire de Paris, Universit\'e PSL, Sorbonne Universit\'e, CNRS, 92190 Meudon, France), S. Ligori (INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese), P. B. Lilje (Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, 0315 Oslo, Norway), V. Lindholm (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland, Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), I. Lloro (SKAO, Jodrell Bank, Lower Withington, Macclesfield SK11 9FT, UK), G. Mainetti (Centre de Calcul de l'IN2P3/CNRS, 21 avenue Pierre de Coubertin 69627 Villeurbanne Cedex, France), D. Maino (Dipartimento di Fisica "Aldo Pontremoli", Universit\`a degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy, INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy, INFN-Sezione di Milano, Via Celoria 16, 20133 Milano, Italy), E. Maiorano (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), O. Mansutti (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), S. Marcin (University of Applied Sciences and Arts of Northwestern Switzerland, School of Computer Science, 5210 Windisch, Switzerland), O. Marggraf (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), M. Martinelli (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy, INFN-Sezione di Roma, Piazzale Aldo Moro, 2 - c/o Dipartimento di Fisica, Edificio G. Marconi, 00185 Roma, Italy), N. Martinet (Aix-Marseille Universit\'e, CNRS, CNES, LAM, Marseille, France), F. Marulli (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), R. J. Massey (Department of Physics, Institute for Computational Cosmology, Durham University, South Road, Durham, DH1 3LE, UK), E. Medinaceli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Mei (Universit\'e Paris Cit\'e, CNRS, Astroparticule et Cosmologie, 75013 Paris, France, CNRS-UCB International Research Laboratory, Centre Pierre Bin\'etruy, IRL2007, CPB-IN2P3, Berkeley, USA), M. Melchior (University of Applied Sciences and Arts of Northwestern Switzerland, School of Engineering, 5210 Windisch, Switzerland), Y. Mellier (Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France, Institut d'Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Universit\'e, 98 bis boulevard Arago, 75014 Paris, France), M. Meneghetti (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), E. Merlin (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), G. Meylan (Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique F\'ed\'erale de Lausanne), A. Mora (Telespazio UK S.L. for European Space Agency), M. Moresco (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), L. Moscardini (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), R. Nakajima (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), C. Neissner (Institut de F\'isica d'Altes Energies, Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra), S. -M. Niemi (European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands), C. Padilla (Institut de F\'isica d'Altes Energies), S. Paltani (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), F. Pasian (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), K. Pedersen (DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155, 2200 Copenhagen, Denmark), W. J. Percival (Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada), V. Pettorino (European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands), S. Pires (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), G. Polenta (Space Science Data Center, Italian Space Agency, via del Politecnico snc, 00133 Roma, Italy), M. Poncet (Centre National d'Etudes Spatiales -- Centre spatial de Toulouse, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France), L. A. Popa (Institute of Space Science, Str. Atomistilor, nr. 409 M\u{a}gurele, Ilfov, 077125, Romania), L. Pozzetti (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), F. Raison (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), R. Rebolo (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Tenerife, Spain, Consejo Superior de Investigaciones Cientificas, Calle Serrano 117, 28006 Madrid, Spain, Universidad de La Laguna, Dpto. Astrof\'i sica, E-38206 La Laguna, Tenerife, Spain), A. Renzi (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), J. Rhodes (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA), G. Riccio (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), E. Romelli (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), M. Roncarelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), R. Saglia (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr.~1, 81679 M\"unchen, Germany, Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), Z. Sakr (Institut f\"ur Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany, Institut de Recherche en Astrophysique et Plan\'etologie, Universit\'e St Joseph, Faculty of Sciences, Beirut, Lebanon), D. Sapone (Departamento de F\'isica, FCFM, Universidad de Chile, Blanco Encalada 2008, Santiago, Chile), B. Sartoris (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr.~1, 81679 M\"unchen, Germany, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), M. Schirmer (Max-Planck-Institut f\"ur Astronomie, K\"onigstuhl 17, 69117 Heidelberg, Germany), P. Schneider (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), A. Secroun (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), G. Seidel (Max-Planck-Institut f\"ur Astronomie, K\"onigstuhl 17, 69117 Heidelberg, Germany), S. Serrano (Institut d'Estudis Espacials de Catalunya, Satlantis, University Science Park, Sede Bld 48940, Leioa-Bilbao, Spain, Institute of Space Sciences), P. Simon (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), C. Sirignano (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), G. Sirri (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), L. Stanco (INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), J. Steinwagner (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), P. Tallada-Cresp\'i (Centro de Investigaciones Energ\'eticas, Medioambientales y Tecnol\'ogicas, Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra), A. N. Taylor (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), I. Tereno (Departamento de F\'isica, Faculdade de Ci\^encias, Universidade de Lisboa, Edif\'icio C8, Campo Grande, PT1749-016 Lisboa, Portugal, Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Faculdade de Ci\^encias, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal), N. Tessore (Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK), S. Toft (Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen, Denmark), R. Toledo-Moreo (Universidad Polit\'ecnica de Cartagena, Departamento de Electr\'onica y Tecnolog\'ia de Computadoras, Plaza del Hospital 1, 30202 Cartagena, Spain), F. Torradeflot (Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra, Centro de Investigaciones Energ\'eticas, Medioambientales y Tecnol\'ogicas), I. Tutusaus (Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Institut de Recherche en Astrophysique et Plan\'etologie), L. Valenziano (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy), J. Valiviita (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland, Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), T. Vassallo (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), A. Veropalumbo (INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy, Dipartimento di Fisica, Universit\`a di Genova, Via Dodecaneso 33, 16146, Genova, Italy), Y. Wang (Caltech/IPAC, 1200 E. California Blvd., Pasadena, CA 91125, USA), J. Weller (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr.~1, 81679 M\"unchen, Germany, Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), G. Zamorani (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), I. A. Zinchenko (Astronomisches Rechen-Institut, Zentrum f\"ur Astronomie der Universit\"at Heidelberg, M\"onchhofstr. 12-14, 69120 Heidelberg, Germany), E. Zucca (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), J. Garc\'ia-Bellido (Instituto de F\'isica Te\'orica UAM-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain), J. Mart\'in-Fleitas (Aurora Technology for European Space Agency), V. Scottez (Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France, ICL, Junia, Universit\'e Catholique de Lille, LITL, 59000 Lille, France) + Kwang-il Seon, Jaehyun Lee, Jongwan Ko, Woowon Byun, Jaewon Yoo, Kyungwon Chun, Sang-Hyun Chun, Sungryong Hong, Jae-Woo Kim, Hong Soo Park, Jihye Shin - The identification of new Herbig Ae/Be stars from LAMOST DR7 - https://arxiv.org/abs/2601.12007 - arXiv:2601.12007v1 Announce Type: new -Abstract: Herbig Ae/Be stars (HAeBes) are critical tracers of intermediate- and high-mass star formation, yet their census remains incomplete compared to low-mass young stellar objects like T-Tauri stars. To expand the known population, we systematically searched for HAeBes in LAMOST DR7 low-resolution spectra. Following Sun et al., we applied Uniform Manifold Approximation and Projection (UMAP) for dimensionality reduction and Support Vector Machine (SVM) classification, identifying $\sim$240,000 spectra with potential H$\alpha$ emission. After removing contaminants (non-stellar objects, extragalactic sources, CVs, and Algol systems) and restricting to B/A-type stars, we obtained 1,835 candidates through 2MASS/WISE visual inspection. Spectral energy distribution analysis confirmed 143 sources with infrared excess ($J$-band or longer wavelengths), including 92 known HAeBes. From the remaining 51 candidates, we classified 26 with strong infrared excess as new HAeBes. Color-index analysis of confirmed HAeBes and classical Ae/Be stars (CAeBes) revealed that the $(K-W1)_0$ vs. $(W2-W3)_0$ diagram effectively separates these populations: CAeBes predominantly occupy $(K-W1)_0 \leq 0.5$ and $(W2-W3)_0 \leq 1.1$, while other regions trace transition disks ($(K-W1)_0 < 0.5$ and $(W2-W3)_0 > 1.1$), globally depleted disks ($(K-W1)_0 > 0.5$ and $(W2-W3)_0 < 1.1$), and Class I/Flat/II HAeBes ($(K-W1)_0 > 0.5$ and $(W2-W3)_0 > 1.1$). More importantly, the HAeBes exhibit a clear evolutionary gradient on this diagram, with those in the Class III, Class II, Flat-SED, and Class I evolutionary stages being effectively distinguished by concentric ellipses that are roughly centered at (0,0) with semi-major axes of $a$=1.5, $a$=3.0, and $a$=4.0, and a semi-major to semi-minor axis ratio of 1.6:1. - oai:arXiv.org:2601.12007v1 + The reason for the occurrence of W-type contact binaries + https://arxiv.org/abs/2601.15672 + arXiv:2601.15672v1 Announce Type: new +Abstract: For more than half a century, the puzzling W-type phenomenon in contact binaries has challenged astrophysicists. In these systems, the less massive component exhibits a higher surface temperature than its more massive companion, which is a reversal of the typical A-type configuration, where the more massive star is hotter. This counterintuitive temperature inversion defies the basic stellar physics and still lacks a widely accepted explanation. In this study, we assembled a sample of over 3,000 extensively observed contact binaries and derived their complete set of physical parameters. Our statistical analysis revealed a strong positive correlation between the occurrence of W-type contact binaries and the intensity and frequency of magnetic activities. This result strongly supports the hypothesis that magnetic activities are the primary driver of the W-type phenomenon and offers a compelling explanation for the observed transitions between the W-type and A-type. + oai:arXiv.org:2601.15672v1 astro-ph.SR - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3847/1538-3881/ae2c4f - Jialin Liu, Jiaming Liu, Jiya Yao, Zhenghao Cheng, Qingyue Qu, Zhicun Liu, Wenyuan Cui, Min Fang + http://creativecommons.org/licenses/by/4.0/ + 10.3847/1538-4365/ae21ce + Zhang et al. 2026, ApJS, 282, 17 + Jia Zhang, Sheng-Bang Qian, Li-Ying Zhu, Xu-Zhi Li - Stability of equilibrium points in modified elliptic restricted three-body problem with various perturbation sources - https://arxiv.org/abs/2601.12026 - arXiv:2601.12026v1 Announce Type: new -Abstract: This study examines the dynamics of the third body in an elliptic restricted three-body problem (ERTBP) framework, taking into account perturbations from radiation pressure, oblateness, and elongation of the primary bodies, as well as disk-like structures. The objectives are to determine the positions and stability of the equilibrium points, asses how these points shift under the influence of perturbations, and evaluate the dependence of their stability on the orbital eccentricity and perturbation parameters. The ERTBP model is modified to include a radiating, oblate primary body and an elongated secondary body modeled as a finite straight segment, alongside perturbations from a surrounding disk. The system's equations of motion are numerically solved using parameters from perturbed and classical cases. Equilibrium positions are computed over a range of eccentricities and perturbation values, and stability is analyzed using linearized equations and eigenvalue methods. In all cases, we have found three collinear ($L_1$, $L_2$, $L_3$) and two non-collinear ($L_4$, $L_5$) equilibrium points solutions. The inclusion of radiations, oblateness, elongation using a finite straight segment, and disk perturbation systematically displaces each equilibrium point from its classical location, with the magnitude and direction of the displacement varying with the perturbation parameter. Stability analysis confirms that the collinear points remain linearly stable under all tested conditions. Meanwhile, non-collinear points are stable under a specific condition. We investigate the stability boundary of these points as a function of orbital eccentricity and we found there is a critical range of eccentricity values within which stability is preserved. - oai:arXiv.org:2601.12026v1 - astro-ph.EP - math.DS - physics.space-ph - Wed, 21 Jan 2026 00:00:00 -0500 + Development of an early warning method incorporating pre-supernova neutrino light curves + https://arxiv.org/abs/2601.15691 + arXiv:2601.15691v1 Announce Type: new +Abstract: Massive stars ($M>8\mathrm{M_\odot}$) emit neutrinos known as pre-supernova (pre-SN) neutrinos through thermal and nuclear interactions for cooling the stellar core during the final stage of stellar evolution. Real-time monitoring of their pre-SN neutrino interaction rate offers a crucial opportunity to issue an early warning to a core-collapse supernova. Some neutrino detectors, including KamLAND and Super-Kamiokande already operate pre-SN alarm systems based on a statistically significant excess of the observed event rate over the expected background. To improve alarm sensitivity, we propose an alarm method which incorporates the time evolution of the observed pre-SN neutrino event rate. The method uses a log likelihood ratio test that references multiple theoretical stellar-evolution models and treats the core collapse time as a nuisance parameter to be profiled over. The performance of the proposed method was evaluated using simulated data for the KamLAND, Super-Kamiokande with dissolved Gadolinium (SK-Gd) and their combined analysis. The results demonstrate a significant improvement in the warning time compared to the conventional rate-only method, while maintaining the same false alarm rate. + oai:arXiv.org:2601.15691v1 + astro-ph.HE + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - M. B. Saputra, H. S. Ramadhan, Ibnu N. Huda, Leonardus B. Putra + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Keita Saito, Minori Eizuka, Zhuojun Hu, Koichi Ichimura, Motoyasu Ikeda, Koji Ishidoshiro, Nanami Kawada, Lucas N. Machado, Lluis Marti-Magro, Kazuha Mikami, Koga Tachibana, Roger A. Wendell - Interior dynamics of envelopes around disk-embedded planets - https://arxiv.org/abs/2601.12074 - arXiv:2601.12074v1 Announce Type: new -Abstract: In the core accretion scenario, forming planets start to acquire gaseous envelopes while accreting solids. Conventional one-dimensional models assume envelopes to be static and isolated. However, recent three-dimensional simulations demonstrate dynamic gas exchange from the envelope to the surrounding disk. This process is controlled by the balance between heating, through the accretion of solids, and cooling, which is regulated by poorly-known opacities. In this work, we systemically investigate a wide range of cooling and heating rates, using three-dimensional hydrodynamical simulations. We identify three distinct cooling regimes. Fast-cooling envelopes ($\beta \lesssim 1$, with $\beta$ the cooling time in units of orbital time) are nearly isothermal and have inner radiative layers that are shielded from recycling flows. In contrast, slow cooling envelopes ($\beta\gtrsim10^3$) become fully convective. In the intermediate regime ($1\lesssim\beta\lesssim300$), envelopes are characterized by a three-layer structure, comprising an inner convective, a middle radiative, and an outer recycling layer. The development of this radiative layer traps small dust and vapour released from sublimated species. In contrast, fully convective envelopes efficiently exchange material from inner to outer envelope. Such fully convective envelopes are likely to emerge in the inner parts of protoplanetary disks ($\lesssim$ 1 au) where cooling times are long, implying that inner-disk super-Earths may see their growth stalled and be volatile depleted. - oai:arXiv.org:2601.12074v1 + Evidence for stellar contamination and water absorption in NGTS-5b's transmission spectra with GTC/OSIRIS + https://arxiv.org/abs/2601.15704 + arXiv:2601.15704v1 Announce Type: new +Abstract: Transmission spectroscopy serves as a valuable tool for probing atmospheric absorption features in the terminator regions of exoplanets. Stellar surface heterogeneity can introduce wavelength-dependent contamination that complicates the interpretation of planetary spectra. We aim to investigate the atmosphere of the warm sub-Saturn NGTS-5b through optical transmission spectroscopy. Two transits were observed with the low-resolution Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) on the 10.4 m Gran Telescopio Canarias (GTC). Chromatic transit light curves were modeled to derive optical transmission spectra and multiple Bayesian spectral retrievals were performed to characterize the atmospheric properties. Model comparisons provide strong evidence for contamination from unocculted stellar spots. A joint retrieval of the transmission spectra, assuming equilibrium chemistry, indicates a relatively clear atmosphere with a sub-solar C/O ratio of $<$0.22 (90% upper limit) and a low metallicity of $0.10^{+0.34}_{-0.05} \times$ solar. Retrievals assuming free chemistry yield strong evidence for the presence of $\rm H_2O$, with its abundance constrained to $\log X_{\mathrm{H_2O}} = -0.79^{+0.14}_{-0.17}$. However, the abundances of other species remain unconstrained due to the limited optical wavelength coverage. The discrepancies between the two NGTS-5b transit spectra can be attributed to varying levels of stellar contamination. NGTS-5b thus appears to host a relatively clear, water-rich atmosphere, pending confirmation from additional observations of molecular bands in the infrared. + oai:arXiv.org:2601.15704v1 astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ayumu Kuwahara, Michiel Lambrechts + http://creativecommons.org/licenses/by/4.0/ + Wan-Hao Wang, Guo Chen, Chengzi Jiang, Enric Palle, Felipe Murgas, Hannu Parviainen - Uncovering the Next Galactic Supernova with the Vera C. Rubin Observatory - https://arxiv.org/abs/2601.12094 - arXiv:2601.12094v1 Announce Type: new -Abstract: Supernovae are observed to occur approximately 1-2 times per century in a galaxy like the Milky Way. Based on historical records, however, the last core-collapse galactic supernova observed by humans occurred almost 1,000 years ago. Luckily, we are well positioned to catch the next one with the advent of new neutrino detectors and astronomical observatories. Neutrino observatories can provide unprecedented triggers for a galactic supernova event as they are likely to see a supernova neutrino signal anywhere from minutes to days before the shock breakout causes the supernova to brighten in optical wavelengths. Given its large etendue, the Vera C. Rubin Observatory is ideally positioned to rapidly localize the optical counterpart based on the neutrino trigger. In this paper we simulate events to study the efficiency with which supernovae are optimally localized by the Vera C. Rubin Observatory. We find that the observatory is ideal for initial localization of nearly all observable supernova triggers and has a 57-97% chance of catching any supernova based on theoretical stellar mass density predictions and observations. We provide an analysis of optimal filter selection and exposure times and discuss observational caveats. - oai:arXiv.org:2601.12094v1 - astro-ph.IM - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Hydrodynamic simulations of the recurrent nova T Coronae Borealis: Nucleosynthesis predictions + https://arxiv.org/abs/2601.15713 + arXiv:2601.15713v1 Announce Type: new +Abstract: T Coronae Borealis (T CrB) is one of the eleven known recurrent novae in our Galaxy. It was observed in outburst in 1866 and 1946, with additional likely eruptions recorded in 1217 and 1787. Given its predicted recurrence period of approximately 80 yr, the next outburst is anticipated to occur imminently, thus motivating a thorough examination of the main characteristics of this system. We present new hydrodynamic models of the explosion of T CrB for different combinations of parameters (i.e., the mass, composition, and initial luminosity of the white dwarf, the metallicity of the accreted matter, and the mass-transfer rate). We show that mass-accretion rates between 10-8 - 10-7 Msun yr-1 are required to trigger an outburst after 80 yr of accretion of solar-composition material onto white dwarfs with masses about 1.30 - 1.38 Msun. For lower white dwarf luminosities, less massive white dwarfs, or reduced metallicity in the accreted material, higher mass-accretion rates are required to drive an explosion within this timescale. A decrease in metallicity or initial white dwarf luminosity leads to higher accumulated masses and ignition pressures, resulting in more violent outbursts. These outbursts exhibit higher peak temperatures, higher ejected masses, and greater kinetic energies. Models computed for different white dwarf masses but identical initial luminosities reveal significant differences in the elemental abundances of a wide range of species, including Ne, Na, Mg, Al, Si, P, S, Ar, K, Ca, and Sc. These compositional differences offer a potential diagnostic tool for constraining the parameter space and discriminating between the various T CrB models reported in this study. + oai:arXiv.org:2601.15713v1 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - John Banovetz, Claire-Alice Hebert, Peter B. Denton, Dan Scolnic, Anze Slosar, Chris Walter + 10.1051/0004-6361/202553762 + Astronomy and Astrophysics (2025), 698, A251 (21 pp) + Jordi Jose, Margarita Hernanz - Detection of a Millisecond Periodicity in BATSE Short Gamma-Ray Bursts - https://arxiv.org/abs/2601.12108 - arXiv:2601.12108v1 Announce Type: new -Abstract: Coherent oscillations at kilohertz frequencies have recently been detected in a small number of gamma-ray bursts (GRBs), suggesting quasi-periodic dynamics in their central engines. A prominent example is GRB~230307A, which exhibited a brief, highly coherent, energy-dependent periodic signal interpreted as the possible spin signature of a nascent millisecond magnetar formed after a compact binary merger. Motivated by these developments, we conducted a comprehensive search for similar signals, accounting for both temporal and spectral dependencies, in 532 short GRBs with time-tagged event data recorded by the Burst and Transient Source Experiment (BATSE) onboard the \textit{Compton Gamma-Ray Observatory}. Within this sample, we identify a single statistically significant case: GRB~960616 (BATSE trigger~5502), in which the $\sim$30~ms main emission episode is coherently modulated at 1100~Hz, with the strongest modulation above 320~keV and a fractional amplitude of $\sim$47\%. Assuming the presence of a coherent periodic modulation, we use data-driven Monte Carlo simulations to place an upper limit of $\sim$8\% on the fraction of the total radiated energy that can be modulated by the QPO. This event, exhibiting a periodicity at $\sim$0.91~ms, further supports the possibility that millisecond periodicities can arise during GRBs in merger-driven scenarios. - oai:arXiv.org:2601.12108v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fuzzy dark matter soliton core hosting a supermassive black hole as a dense low-mass perturber in strong gravitational lensing + https://arxiv.org/abs/2601.15718 + arXiv:2601.15718v1 Announce Type: new +Abstract: Recent high-resolution imaging observations of strong lens systems reveal dense low-mass perturbers. We propose a soliton core, whose central density is boosted by a supermassive black hole (SMBH), in the fuzzy dark matter (FDM) model as an efficient perturber in strong gravitational lensing. The higher central density makes it less efficient in the tidal mass loss, and leads to the higher impact in gravitational lensing. We show that the mass profile of a $\sim 10^6M_\odot$ perturber in JVAS B1938+666, which does not resemble any known astronomical object, can be wel explained by a soliton core in the FDM model with the mass of $4\times 10^{-21}$eV hosting an SMBH with the mass of $4\times 10^5M_\odot$. The high mass of the SMBH may be explained by several scenarios that predcit heavy SMBH seeds such as the direct collapse black hole formation and primordial black holes. + oai:arXiv.org:2601.15718v1 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Run-Chao Chen, Jun Yang, Yi-Han Iris Yin, Bin-Bin Zhang + Masamune Oguri, Naoi Kubo - Timing analysis of a sample of five cataclysmic variable candidates observed by the XMM-Newton satellite - https://arxiv.org/abs/2601.12127 - arXiv:2601.12127v1 Announce Type: new -Abstract: Intermediate polars are a class of cataclysmic variables in which a white dwarf accretes material from a companion star. The intermediate polar nature confirmation usually derives from the detection of two periods in both $X$-ray and optical photometry. In this respect, the high energy signal is often characterized by modulations on the white dwarf spin and the orbital period. However, noting that the periodograms may be characterized by strong features also at the synodic period and/or other sidebands, the timing analysis of the $X$-ray signal may offer the unique possibility to firmly discover an intermediate polar candidate. Here, we concentrate on a sample of five cataclysmic variable {binary} candidates: {i.e. SAXJ1748.2-2808, 1RXS J211336.1+542226, CXOGC J174622.7-285218, CXOGC J174517.4-290650, and V381 Vel, listed in the IPHome catalogue. Our main aim is to confirm if they belong to the intermediate polar class or not. The results of our analysis show that we can safely assess the intermediate polar nature of all the considered sources, apart for the case of V381 Vel which instead behaves like a cataclysmic variable of the polar subclass. Moreover, the source SAXJ1748.2-2808, previously classified as a HMXB, appears to be, most likely, an intermediate polar variable. - oai:arXiv.org:2601.12127v1 - astro-ph.HE + Interaction between the ejecta, the accretion disk, and the secondary star in the recurrent nova system U Sco + https://arxiv.org/abs/2601.15725 + arXiv:2601.15725v1 Announce Type: new +Abstract: Most efforts in the modeling of recurrent novae have centered on the initial phases of the explosion and ejection, overlooking the subsequent interaction of the ejecta, first with the accretion disk orbiting the white dwarf and ultimately with the secondary star. To address this gap, a series of 3D smoothed-particle hydrodynamics simulations was conducted. These simulations explored the dynamic interactions between the nova ejecta, accretion disk, and stellar companion within the framework of the recurrent nova system U Sco. Notably, the simulations incorporate rotation around the system's center of mass. The primary goal of these simulations was to qualitatively examine the impact of various model parameters, including ejecta mass, velocity, and density, as well as the mass and geometry of the accretion disk. Simulations reveal complete disruption and sweeping of the accretion disk orbiting the white dwarf star for models with flared disks and Mejecta/Mdisk larger than 1. In contrast, V-shaped disks with a (constant) high initial density and Mejecta/Mdisk < 1 partially survive the impact with the nova ejecta. A very minor chemical contamination of the secondary star is anticipated in the U Sco case based on the limited impact of nova ejecta particles on the subgiant in all simulations. Minor mass ejection from the subgiant's outer layers is observed during the late-stage collision with ejecta and disk material, with some particles ejected from the binary system and some accreted by the white dwarf. + oai:arXiv.org:2601.15725v1 astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1093/mnras/stac2687 - MNRA, 2022, Volume 517, Issue 1, pp.118-129 - A. A. Nucita, S. M. Lezzi, F. De Paolis, Strafella, D. Licchelli, A. Franco, M. Maiorano + http://creativecommons.org/licenses/by/4.0/ + 10.1051/0004-6361/202449972 + Astronomy & Astrophysics (2025), 693, A209 (10 pp) + Joana Figueira, Jordi Jose, Ruben Cabezon, Domingo Garcia-Senz - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) III: The vertical structure of debris disks - https://arxiv.org/abs/2601.12128 - arXiv:2601.12128v1 Announce Type: new -Abstract: Debris disks -- collisionally sustained belts of dust and sometimes gas around main sequence stars -- are remnants of planet formation processes and are found in systems ${\gtrsim}10$ Myr old. Millimeter-wavelength observations are particularly important, as the grains probed by these observations are not strongly affected by radiation pressure and stellar winds, allowing them to probe the dynamics of large bodies producing dust. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) is analyzing high-resolution observations of 24 debris disks to enable the characterization of debris disk substructures across a large sample for the first time. For the most highly inclined disks, it is possible to recover the vertical structure of the disk. We aim to model and analyze the most highly inclined systems in the ARKS sample in order to uniformly extract the vertical dust distributions for a sample of well-resolved debris disks. We employed both parametric and nonparametric methods to constrain the vertical dust distributions for the most highly inclined ARKS targets. We find a broad range of aspect ratios, revealing a wide diversity in vertical structure, with a range of best-fit parametric values of $0.0026 \leq h_{\rm HWHM} \leq 0.193$ and a median best-fit value of $h_{\rm HWHM}=0.021$. The results obtained by nonparametric modeling are generally consistent with the parametric modeling results. We find that five of the 13 disks are consistent with having total disk masses less than that of Neptune (17 $M_{\oplus}$), assuming stirring by internal processes (self-stirring and collisional and frictional damping). Furthermore, most systems show a significant preference for a Lorentzian vertical profile rather than a Gaussian. - oai:arXiv.org:2601.12128v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + GRB~250704B/EP250704a a Short Gamma-Ray Burst Powered by a Magnetar + https://arxiv.org/abs/2601.15732 + arXiv:2601.15732v1 Announce Type: new +Abstract: GRB~250704B/EP250704a, identified as a short gamma-ray burst (sGRB), exhibited prolonged X-ray emission following the prompt phase and, in optical and infrared (IR) bands, an unusual one-day plateau succeeded by a rapid decline. This sGRB was observed by multiple satellites and ground-based observatories across the electromagnetic spectrum. This study presents temporal and spectral analyses from radio to gamma-ray frequencies, spanning several observation periods beginning after the trigger and continuing for nearly 2 days. The results of the temporal and spectral analyses of the prompt episode, the extended X-ray component, and the afterglow phase are consistent with a millisecond magnetar undergoing accretion. The long-lasting X-ray emission is attributed to the internal energy dissipation of the magnetar spin-down power, governed by the magnetization parameter; the extended optical/IR plateau to synchrotron afterglow emission with energy injection; and the steep decay to changes in microphysical parameters during the post-jet break phase. The X-ray observations are consistent with the superposition of spin-down luminosity and synchrotron afterglow scenario. These findings suggest that the compact-object remnant is most likely a long-lived magnetar. + oai:arXiv.org:2601.15732v1 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - 10.1051/0004-6361/202556505 - A&A, 705, A197 (2026) - Brianna Zawadzki, Anna Fehr, A. Meredith Hughes, Elias Mansell, Jamar Kittling, Yinuo Han, Catherine Hou, Margaret Pan, Julien Milli, Johan Olofsson, Tim D. Pearce, Antranik A. Sefilian, Aliya Nurmohamed, Junu Lee, Yamani Mpofu, Myriam Bonduelle, Mark Booth, Aoife Brennan, Carlos del Burgo, John M. Carpenter, Gianni Cataldi, Eugene Chiang, Steve Ertel, Thomas Henning, Marija R. Jankovic, Grant M. Kennedy, \'Agnes K\'osp\'al, Alexander V. Krivov, Joshua B. Lovell, Patricia Luppe, Meredith A. MacGregor, Sorcha Mac Manamon, Sebastian Marino, Jonathan P. Marshall, Luca Matr\`a, Attila Mo\'or, Sebasti\'an P\'erez, Philipp Weber, David J. Wilner, Mark C. Wyatt + Nissim Fraija, Antonio Galv\'a, Boris Betancourt Kamenetskaia, Maria G Dainotti - Exploring Superfluid Angular Momentum Reservoir Effect on Pulsar Glitches and Forecasting Next Glitches of the Crab Pulsar - https://arxiv.org/abs/2601.12130 - arXiv:2601.12130v1 Announce Type: new -Abstract: Pulsar glitches are generally viewed as stochastic events driven by sudden angular momentum transfer from the neutron star's superfluid interior to its crust. Except two peculiar pulsars with quasi-periodic glitches, this stochastic view has prevailed. Here, by clustering temporally proximate small glitches of the Crab pulsar, we uncover clear evidence of an underlying quasi-periodic modulation, challenging the paradigm of purely random behavior. Furthermore, our correlation analyses reveal a strong positive relationship between glitch cluster size and waiting time since the preceding clusters. These findings demonstrate the effect of angular momentum reservoir operating over long-term scales and enable the predictions of next glitching window. Remarkably, two minor glitches detected in July and August 2025, which align with our initial prediction made in June, should be confirmed as the onset of this predicted activity. Inspired by the initial success, we forecast the occurrence of a major glitch from now until August 2026, with possible glitch size up to a relative change in rotational frequency of $697.2 \times 10^{-9}$. Physically, the observed long-term quasi-periodicity and cluster size-waiting time correlations imply that each glitch event releases only a fraction of the stored superfluid angular momentum. This partial-release mechanism provides a unified framework for both stochastic and quasi-periodic glitch behaviors across different pulsars, underscoring the universality of the superfluid angular momentum reservoir effect. As the most intensively monitored object, the Crab pulsar serves as a natural laboratory for studying angular momentum inside neutron stars. - oai:arXiv.org:2601.12130v1 + Nucleosynthesis in Type Ia Supernovae, Classical Novae, and Type I X-Ray Bursts. A Primer on Stellar Explosions + https://arxiv.org/abs/2601.15740 + arXiv:2601.15740v1 Announce Type: new +Abstract: Nuclear astrophysics aims at unraveling the cosmic origins of chemical elements and the physical processes powering stars. It constitutes a truly multidisciplinary field, that integrates tools, advancements, and accomplishments from theoretical astrophysics, observational astronomy, cosmochemistry, and theoretical and experimental atomic and nuclear physics. For instance, the advent of high-energy astrophysics, facilitated by space-borne observatories, has ushered in a new era, offering a unique, panchromatic view of the universe (i.e., allowing multifrequency observations of stellar events); supercomputers are also playing a pivotal role, furnishing astrophysicists with computational capabilities essential for studying the intricate evolution of stars within a multidimensional framework; cosmochemists, through examination of primitive meteorites, are uncovering tiny fragments of stardust, shedding light on the physical processes operating in stars and on the mechanisms that govern condensation of stellar ejecta into solids; simultaneously, nuclear physicists managed to measure nuclear reactions at (or close to) stellar energies, using both stable and radioactive ion beam facilities. This paper provides a multidisciplinary view on nucleosynthesis accompanying stellar explosions, with a specific focus on thermonuclear supernovae, classical novae, and type I X-ray bursts. + oai:arXiv.org:2601.15740v1 + astro-ph.SR astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Pei-Xin Zhu, Xiao-Ping Zheng, Quan Cheng, Chenghui Niu, Erbil G\"ugercino\u{g}lu + http://creativecommons.org/licenses/by/4.0/ + 10.1051/epjconf/202429701006 + EPJ Web Conf. (2024) 297, 01006 (9 pp) + Jordi Jose - Discovery of a soft X-ray lag in the tidal disruption event AT2021ehb - https://arxiv.org/abs/2601.12240 - arXiv:2601.12240v1 Announce Type: new -Abstract: In this Letter, we report the detection of soft X-ray time lags-i.e. variability in the softer photons lagging behind that in the harder photons-in seven XMM-Newton observations of the tidal disruption event (TDE) candidate AT2021ehb. We find correlated variability between the soft (0.3-0.7 keV) and hard (0.9-10 keV) bands on about 10^4 s time-scales, and measure a soft lag of about 500 s. This behaviour is broadly consistent with the disk-corona reverberation scenario established in active galactic nuclei (AGNs). Together with the previously reported strong hard X-ray emission and broad Fe K line, our results suggest the presence of a compact corona and prominent relativistic disk reflection in AT2021ehb. The unusually high blackbody temperature (peaking at about 200 eV) is difficult to reconcile with thermal emission from a standard accretion disk around a about 10^7 Msun black hole, and may instead be analogous to the soft excess commonly observed in AGNs, whose physical origin remains debated. Finally, the measured lags offer a possible explanation for the rapid X-ray flux decline that occurred only three days after the peak, pointing to a scenario in which the corona cools following a sudden loss of the magnetic support required to sustain it. - oai:arXiv.org:2601.12240v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Redshift-Binned Constraints on the Hubble Constant under $\Lambda$CDM, CPL, and Pad\'e Cosmography + https://arxiv.org/abs/2601.15765 + arXiv:2601.15765v1 Announce Type: new +Abstract: Motivated by recent claims of a possible redshift dependence in late-Universe determinations of the Hubble constant ($H_0$), we test the robustness of this behaviour using multiple cosmological probes. We perform a joint redshift-binned analysis of $H_0$ across eight bins using late-Universe probes -- Pantheon+ SNe~Ia, DESI BAO, cosmic chronometers, and water megamasers -- under three cosmological frameworks: flat $\Lambda$CDM, CPL, and Pad\'e cosmography. Under a common baseline scheme, all three models show a qualitatively similar, low-amplitude variation in the per-bin $H_0$ estimates. A simple Fourier-like parametrization captures this behaviour, but the amplitude differs from zero only at a marginal significance of about $1.71$--$1.94\,\sigma$, with similar behaviour observed across all three cosmological frameworks. We then investigate the robustness and possible origin of this feature. Alternative binning schemes preserve its qualitative form, whereas single-probe per-bin fits (SNe-only, CC-only, BAO-only) yield ratios $H_{0,i}/H_{0,\mathrm{global}}$ mostly consistent with unity and do not reproduce the pronounced drift seen in the joint baseline constraints. Finally, by comparing different global versus piecewise-constant configurations for $\{H_0,\Omega_m,M,r_d\}$, we find that a baseline-like oscillatory pattern re-emerges only when multiple degenerate parameter combinations are allowed to vary across bins, while it is strongly suppressed when only $H_0$ is bin-dependent. Taken together, these results indicate that the apparent oscillatory behaviour of $H_0(z)$ in late-time arises from known parameter degeneracies and does not constitute robust evidence for a genuine redshift evolution. + oai:arXiv.org:2601.15765v1 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Wenjie Zhang + 10.1103/cm3y-2nqq + Zhi-Yuan Mo, Kang Jiao, Tong-Jie Zhang - Reconciling the Systemic Kicks of Observed Millisecond Pulsars, Spider Pulsars, and Low-mass X-ray Binaries - https://arxiv.org/abs/2601.12275 - arXiv:2601.12275v1 Announce Type: new -Abstract: Millisecond pulsars (MSPs) have been proposed as evolutionary products of low-mass X-ray binaries (LMXBs) through a stage in which they are spider pulsars (i.e., redbacks and black widows). However, recent work has found that the systemic kicks of observed MSPs are significantly lower than the kicks of LMXBs and spiders, which appears to be in tension with this evolutionary model. We argue that this tension can be relieved, at least to some degree, by considering the fact that the observed MSPs are located at relatively short distances, whereas spider pulsars are located at greater distances and LMXBs are situated even further away. We model the distance-dependent kinematic bias for dynamically old objects, which favors observing objects that have received low kicks at short distances and correct the observed systemic kicks for this bias. We find that this kinematic bias can be big enough to close the gap between the MSP and LMXB kicks, although the spider pulsars appear to come from a slightly different systemic kick distribution, but this difference is not necessarily physical. All corrected systemic kick distributions are consistent with predictions from binary population synthesis for progenitor systems with a post-supernova orbital period of $P_{\text{orb}}\leq10\,$d and a companion mass of $M_{c}\leq1\,M_{\odot}$, where the natal kicks are calibrated to the velocities of young isolated pulsars. We conclude that the difference in observed systemic kicks is not necessarily in tension with a common origin for MSPs, spider pulsars, and LMXBs. - oai:arXiv.org:2601.12275v1 - astro-ph.HE + Deuteration of HC3N and CH3CCH in the pre-stellar core L1544 + https://arxiv.org/abs/2601.15791 + arXiv:2601.15791v1 Announce Type: new +Abstract: Deuterated molecules are a useful diagnostic tool to probe the evolution and the kinematics in the earliest stages of star formation. Due to the low temperatures and high densities in the centre of pre-stellar cores, the deuterium fraction is enhanced by several orders of magnitude. We study the distribution of the emission and the deuteration of the two carbon chains HC3N and CH3CCH throughout the pre-stellar core L1544. We analyse emission maps of CH3CCH, CH2DCCH, CH3CCD, HC3N, HCC13CN, and DC3N, observed with the IRAM 30m single-dish radio telescope. We use non-LTE radiative transfer calculations, combined with chemical modelling of the molecular abundances, to constrain physical parameters of the observed species. Following this, we derive the column density and deuteration maps. We find D-fractions of N(DC3N)/N(HC3N)=0.04-0.07, N(CH2DCCH)/N(CH3CCH)=0.09-0.15, and N(CH3CCD)/N(CH3CCH)=0.07-0.09. The deuteration of HC3N appears homogeneous across the core, with widespread D-fraction values above 0.06, tracing intermediate-density gas in the outer layers of the core. CH3CCD is most efficiently formed in the higher-density regions towards the core centre, while the D-fraction of CH2DCCH traces a local density enhancement in the north-east of the core, coinciding with the CH3OH emission peak. The results suggest that gas-phase reactions dominate the formation and deuteration of both HC3N and CH3CCH in L1544, with spatial variations driven by physical structure, density and external radiation. The significantly higher D-fraction of CH2DCCH compared to CH3CCD and a tentative gradient with higher values in the north suggest different deuteration mechanisms for the two functional groups. Similarities between the CH2DCCH emission and CH2DOH might indicate an additional deuteration pathway of CH3CCH on the surfaces of dust grains, as observed for H2CO. + oai:arXiv.org:2601.15791v1 astro-ph.GA - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Paul Disberg, Arash Bahramian, Ilya Mandel + K. Giers, S. Spezzano, Y. Lin, P. Caselli, O. Sipil\"a - The MAGPI Survey: co-evolution of baryons and dark matter in star-forming disk-like galaxies at $0.1 \lesssim z \lesssim 0.85$ - https://arxiv.org/abs/2601.12315 - arXiv:2601.12315v1 Announce Type: new -Abstract: We present a comprehensive analysis of the dark matter (DM) content and its structural dependence in star-forming disk-like galaxies at intermediate redshifts ($0.1 \lesssim z \lesssim 0.85$), utilizing spatially resolved kinematic data from the MAGPI survey. We report the following: (1) Low stellar mass galaxies ($M_{\rm star} < 10^{9.5}\, M_\odot$) are strongly DM dominated across all radii, with average $\langle f_{_{\rm DM}} \rangle \sim 0.85$, while high-mass ($M_{\rm star} > 10^{10.5}\, M_\odot$) systems exhibit relatively low DM fractions in their inner regions ($\langle f_{_{\rm DM}} \rangle \sim 0.47$) which is equivalent to local massive disk galaxies (e.g., Milky Way and Andromeda). This suggests a mass-dependent structural dichotomy, most-likely governed by a combination of internal galactic processes and environmental influences. (2) A tight inverse correlation between $f_{_{\rm DM}}$ and baryon mass surface density ($\Sigma_{\rm bar}$), with intrinsic scatter of $\sim 0.11$ dex. This is consistent with an inside-out baryon assembly scenario and suggests that the fundamental structural correlations of galaxies were already established by $z\sim 0.85$. (3) No significant evolution in $f_{_{\rm DM}}$ with redshift across the MAGPI window, and when combined with higher-redshift ($0.6 \leq z \leq 1.5$) data from Sharma et al. 2025, we quantitatively show that the reported decline in $f_{_{\rm DM}}(z)$ is most-likely due to observational biases against low-mass systems at $z > 1$. These results offer empirical evidence for a scenario in which disk-like galaxies evolve through a co-regulated build-up of baryonic and DM components, preserving internal structural regularities (such as the total mass distribution and rotation-curve shape) throughout cosmic time. - oai:arXiv.org:2601.12315v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Distance-Independent Atmospheric Refraction Correction for Accurate Retrieval of Fireball Trajectories + https://arxiv.org/abs/2601.15805 + arXiv:2601.15805v1 Announce Type: new +Abstract: Accurate determination of fireball direction is essential for retrieving trajectories and velocities. Errors in these measurements have significant implications, affecting the calculated pre-impact orbit, influencing mass estimates, and impacting the accuracy of dark flight simulations, where applicable. Here we implement a new atmospheric refraction correction technique that addresses a significant aspect previously overlooked in the field of meteor science. Traditional refraction correction techniques, originally designed for objects positioned at infinite distances, tend to overcompensate when applied to objects within the Earth's atmosphere. To rectify this issue, our study introduces the concept of the atmospheric refraction delta z correction technique, involving the artificial elevation of the observer site height above sea level. We utilize analytically derived formulas for the delta z correction in conjunction with commonly used refraction models, validating these results against a numerical solution that traces light rays through the atmosphere. This ray-tracing model is applied to finely meshed atmospheric layers, yielding precise correction values. We evaluate multiple sources of error in order to quantify the achievable accuracy of the proposed method. Our approach (1) enables the determination of fireball positions with improved astrometric accuracy, (2) removes the explicit dependence on the fireball distance from the observer or its height above Earth's surface within the limits imposed by realistic atmospheric variability, and (3) simplifies meteor data processing by providing a robust framework for analyzing low-elevation fireball observations, for which atmospheric refraction is significant and is automatically corrected by the method. As a result of this work, we provide open, publicly accessible software for calculating the delta z correction. + oai:arXiv.org:2601.15805v1 + astro-ph.IM + astro-ph.EP + physics.ao-ph + physics.geo-ph + physics.optics + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Gauri Sharma, Andrew J. Battisti, Emily Wisnioski, J. Trevor Mendel, Sabine Bellstedt, Claudia Del P. Lagos, Caroline Foster, Adriano Poci, Katherine E. Harborne, Ryan Bagge, Stefania Barsanti, Joss Bland-Hawthorn, Iris Breda, Scott M. Croom, Karl Glazebrook, Yifan Mai, Sarah M. Sweet, Sabine Thater, Lucas M. Valenzuela, Glenn van de Ven, Sukyoung Yi, Tayyaba Zafar, Bodo Ziegler + Jaakko Visuri, Maria Gritsevich, Janne Sievinen - Unveiling the First O-Type Bloated Star Candidate through ALMA and EVLA Observations - https://arxiv.org/abs/2601.12336 - arXiv:2601.12336v1 Announce Type: new -Abstract: We investigate the circumstellar environment of the O-type bloated star candidate IRAS 19520+2759 (I19520) using high-resolution observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Expanded Very Large Array (EVLA). Radio continuum emission traced by the EVLA (C, K, and Q bands) exhibits a spectral index of 0.5, consistent with a thermal jet. ALMA 1.3 mm continuum map reveals a compact source coincident with the optical counterpart of I19520, likely tracing the dense core hosting the central massive young stellar object. A prominent molecular outflow in the east-west direction, along with a possible secondary outflow oriented northeast-southwest, is identified in the $^{13}\mathrm{CO}$ emission. A hot molecular core and a Keplerian disk are detected in several $\mathrm{SO}_2$ transitions. Assuming an edge-on disk geometry, the dynamical mass of the central object is estimated to be in the range of $10$-$15~M_\odot$. - oai:arXiv.org:2601.12336v1 + Failed ejection and oscillations of a current-carrying filament balanced by gravity + https://arxiv.org/abs/2601.15823 + arXiv:2601.15823v1 Announce Type: new +Abstract: In this study, we investigate the post-destabilization evolution of a filament in a gravity-balanced model. We adopt the filament model proposed by Solov'ev (2010), in which a dense filament is supported against gravity by the repulsive force between the filament current and its sub-photospheric image. We first performed an analytical investigation of this model. For the numerical study, we use a two-dimensional magnetohydrodynamic (MHD) model that solves the MHD equations with the Lare2d numerical code. Results: In this filament model, analytical expressions are derived for the electric current density, plasma density, and their spatial distributions as functions of the model parameters. The total electric current and the filament weight are also calculated. For the numerical simulations, we constructed an equilibrium filament characterized by a magnetic field of $B_0$ = $10^{-3}$ T, mass density $\rho_0$ ~ 1.3 x $10^{-9}$ kg m$^{-3}$, and temperature T ~ 13000 K. The system was destabilized either by increasing the currents or by reducing the filament density, and its evolution was computed. In both destabilization regimes, the filament was ejected, then halted at a certain altitude, and subsequently fell back, repeating this cycle with a period of about 600 s. The maximum filament ejection velocity was approximately 80 and 40 km $s^{-1}$, respectively. Beneath the ejected filament a current sheet forms, where magnetic reconnection occurs. The maximum ejection altitudes were determined as functions of both the destabilizing currents and the degree of filament plasma dilution. Finally, we compared results of this MHD model with those of an ideal vacuum model and discussed all results. + oai:arXiv.org:2601.15823v1 astro-ph.SR - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Rakesh Pandey, Aina Palau, Alvaro S\'anchez-Monge, Raghvendra Sahai, Rolf Kuiper, Luis F. Rodr\'iguez, Carmen S\'anchez Contreras, Saurabh Sharma + http://creativecommons.org/publicdomain/zero/1.0/ + P. Jel\'inek, M. Karlick\'y, S. Belov - Revisiting the exoplanet radius valley with host stars from SWEET-Cat - https://arxiv.org/abs/2601.12396 - arXiv:2601.12396v1 Announce Type: new -Abstract: The radius valley,a deficit of planets near 2 $\mathrm{R_{\oplus}}$, was observed among exoplanets of radius $\lesssim$ 5 $\mathrm{R_{\oplus}}$ with periods $<$ 100 days by NASA's $Kepler$ mission. It separates super-Earths (rocky, $\lesssim 1.9$ $\mathrm{R_{\oplus}}$) from sub-Neptunes (volatile-rich, $\gtrsim 2$ $\mathrm{R_{\oplus}}$) and may arise from formation conditions or atmospheric loss. Disentangling these mechanisms has led to numerous studies of population-level trends, although the resulting interpretations remain sensitive to sample selection and the robustness of host-star parameters. We re-examine its existence, depth, and dependence on period, flux, stellar mass, and age. Using SWEET-Cat and MAISTEP tool, we derived stellar parameters for 1,221 main-sequence stars (1,405 planets), with effective temperatures 4400--7500 K and radii 0.62--2.75 $\mathrm{R_{\odot}}$, achieving 2\% precision in radius and mass. Planetary radii were recomputed from radius ratios, yielding 5\% median uncertainty. The valley is partially filled near 2 $\mathrm{R_{\oplus}}$ and depends on period, flux, and stellar mass, with slopes $-0.12^{+0.02}_{-0.01}$, $0.10^{+0.02}_{-0.03}$, and $0.19^{+0.09}_{-0.07}$. Sub-Neptunes show a stronger stellar mass-dependent trend than super-Earths ($0.17^{+0.04}_{-0.04}$ vs $0.11^{+0.05}_{-0.05}$). With stellar age, the super-Earth/sub-Neptune ratio rises from $0.51^{+0.11}_{-0.08}$ ($<3$ Gyr) to $0.64^{+0.11}_{-0.11}$ ($\gtrsim3$ Gyr), and the valley becomes shallower and shifts to larger radii. A 4D fit shows consistent slopes with 2D analyses and a weaker age trend ($0.07^{+0.03}_{-0.04}$). These results suggest prolonged atmospheric loss, which is consistent with a core-powered mass loss scenario and emphasize the need for improved determinations, a goal expected to be achieved by future missions like PLATO. - oai:arXiv.org:2601.12396v1 - astro-ph.EP - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Radio-Interferometric Image Reconstruction with Denoising Diffusion Restoration Models + https://arxiv.org/abs/2601.15844 + arXiv:2601.15844v1 Announce Type: new +Abstract: Reconstructing images of the radio sky from incomplete Fourier information is a key challenge in radio astronomy. In this work, we present a method for radio interferometeic image reconstruction using a data-driven prior for the radio sky based on denoising diffusion probabilistic models (DDPMs). We first train a DDPM on radio galaxy observations from the VLA FIRST survey. We create simulated VLA, EHT, and ALMA observations of radio galaxies, then use an unsupervised posterior sampling method called Denoising Diffusion Restoration Models (DDRM) to reconstruct the corresponding images, using our DDPM as a prior. Our approach is agnostic to the measured radio interferometric data and naturally incorporates the physics of the measurement process. We are able to reconstruct images with very high fidelity PSNR>60, a marked improvement over CLEAN and similar image reconstruction methods using conditional DDPMs + oai:arXiv.org:2601.15844v1 + astro-ph.IM + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Juma Kamulali, Vardan Adibekyan, Benard Nsamba, Sergio G. Sousa, Tiago. L. Campante, Achim Weiss, Bridget Kabugho, Nuno Moedas, Nuno C. Santos, Otto Trust + Michel Morales, Emma Tolley, Remi Poitevineau - Updated indicators of oxygen metallicity for high-$z$ galaxies - https://arxiv.org/abs/2601.12413 - arXiv:2601.12413v1 Announce Type: new -Abstract: Recent work has demonstrated that widely used strong-line oxygen abundance indicators, such as O3N2, $\rm R23$, and $\widehat{\rm R}$, suffer from large uncertainties when applied to high-redshift galaxies. We show that this loss of precision primarily arises because, at fixed \Oabund, galaxies span a wide dynamic range in ionization parameter and nitrogen enrichment. Here we develop updated indicators that explicitly incorporate both effects via the proxies O32 and N2O2. We define ${\rm R}_{\rm u}\equiv \rm R23+\alpha_1 O32+\alpha_2 N2O2$, $\widehat{\rm R}_{\rm u}\equiv \rm \widehat{R}+\beta_1 O32+\beta_2 N2O2$, and ${\rm O}_{\rm u}\equiv \rm O3N2+\gamma_1 O32+\gamma_2 N2O2$, and calibrate \Oabund~as low-order polynomials in each composite indicator. Applied to a JWST sample with $T_{\rm e}$-method abundances, the updated indicators substantially tighten the correlations with \Oabund, boosting adjusted coefficients of determination from $\mathbb{R}^2\lesssim 0$ (classical indicators) to $\mathbb{R}^2\gtrsim 0.5$ for the full sample and to $\sim 0.7$ at $z>2$. The residuals reveal a redshift evolution in the mapping between \Oabund, strong lines, ionization, and nitrogen enrichment, with a pivotal turning point near the cosmic noon ($z\sim 2$). Our calibrations provide a practical, physically grounded path to precise metallicity measurements in the JWST era and a firmer basis for quantifying early chemical enrichment and feedback. - oai:arXiv.org:2601.12413v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Intrinsic alignments in the FLAMINGO simulations with two-point statistics + https://arxiv.org/abs/2601.15851 + arXiv:2601.15851v1 Announce Type: new +Abstract: Intrinsic alignments are a major astrophysical contaminant for next generation large-sky surveys like Euclid and LSST. Large hydrodynamic simulations are crucial for informing the alignment modelling for these surveys. We measure position-position and position-shape correlations of a Luminous Red Galaxy sample from the FLAMINGO suite of hydrodynamical simulations, measuring the alignment signal for more than 4.9 million galaxies at redshift 0. We jointly model the clustering and alignment correlations to provide the tightest constraints on the alignment amplitude to date from a hydrodynamic simulation. We find that both the Non-Linear Alignment (NLA) and the more complex Tidal Alignment Tidal Torquing (TATT) models provide good fits to the data. We compare the measured $A_1$ amplitude to observational data and find good agreement. We measure the dependence of the NLA and TATT free parameters on halo mass. We also introduce a mass-dependent TATT model, TATT-M, by finding empirical relations between the halo mass and the TATT parameters. This allows us to fit TATT with only one parameter, $A_1$, with $A_2/A_1$ being a constant and $A_{1\delta}/A_1$ being a function of halo mass. Using a Bayesian approach, we find that TATT-M is very strongly preferred by the data over NLA. Using the baryonic feedback variations of the FLAMINGO simulation suite, we test whether the TATT parameters are sensitive to feedback. Variations in AGN and supernova feedback do not significantly change the alignment amplitude beyond the change associated with the dependence of galaxy stellar mass on the strength of feedback. Our results inform the IA modelling for upcoming surveys by providing guidance on model choices, priors and sensitivities to feedback. + oai:arXiv.org:2601.15851v1 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Shihong Liu, Yu Rong, Tie Li, Yao Yao, Cheng Jia, Enci Wang, Hongxin Zhang, Zhicheng He, Huiyuan Wang, Xu Kong + A. Herle, N. E. Chisari, H. Hoekstra, D. Navarro-Giron\'es, M. Schaller, J. Schaye - Probing Circumstellar Material and Shock Acceleration in Core-Collapse Supernovae with High-Energy Neutrinos - https://arxiv.org/abs/2601.12417 - arXiv:2601.12417v1 Announce Type: new -Abstract: We study high-energy (HE) neutrino production from interactions between supernova (SN) ejecta and the surrounding circumstellar material (CSM), focusing on regular Type~II and Type~IIn SNe. Using observationally inferred CSM density distributions, we calculate the resulting neutrino fluxes and examine their dependence on key parameters, including the CSM density normalization $D_*$, outer radius $R_{\rm csm}$, proton acceleration efficiency $\epsilon_p$, and magnetic energy fraction $\epsilon_B$. Detection prospects are assessed with a binned likelihood analysis for IceCube, indicating that nearby SNe with moderately dense, confined CSM can produce detectable signals, with a typical detection horizon of $\sim 0.1$ - 1 Mpc. For a Galactic SN at $\sim 10$ kpc, high-statistics neutrino data with detailed temporal and spectral information can constrain $D_*$, $R_{\rm csm}$, and $\epsilon_p$ to within a factor of $\sim 10$ or to a precision of $\sim 20\%$, depending on the assumed values of $D_*$ and $R_{\rm csm}$. These neutrino signals thus provide a complementary probe of the CSM profile and shock acceleration, alongside traditional electromagnetic observations. - oai:arXiv.org:2601.12417v1 - astro-ph.HE - hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 + Does the solar oxygen abundance change over the solar cycle? An investigation into activity-induced variations of the O I infrared triplet + https://arxiv.org/abs/2601.15919 + arXiv:2601.15919v1 Announce Type: new +Abstract: The determination of the solar oxygen abundance remains a central problem in astrophysics, as its accuracy is limited not only by models but also by systematics. While many of these factors have been thoroughly characterized, the effect of the solar activity cycle has so far remained unexplored. Due to its relative strength and accessibility, the O I infrared triplet is typically the primary choice for abundance studies. However, previous investigations have shown that abundances inferred from this triplet tend to be higher than expected on active stars, whereas such an overabundance effect is not observed for the much weaker forbidden O I 6300 \r{A} line. This raises the question of whether a similar trend can be found for the Sun. To address this question, we analyze two decades' worth of synoptic disk-integrated Sun-as-a-star datasets from the FEROS, HARPS-N, PEPSI, and NEID spectrographs, focusing on the infrared triplet (7772, 7774, 7775 \r{A}) and the forbidden O I 6300 \r{A} line. The excellent signal-to-noise ratio of the PEPSI observations allows us to detect a weak but significant variation in the equivalent widths of the infrared triplet, corresponding to about 0.01 dex difference in abundance between activity minimum and maximum. This value is significantly smaller than the typical uncertainties on the solar oxygen abundance. Due to higher scatter, no comparable trend is found in the other data sets. Based on these results, we conclude that within the typical uncertainties presented in other works, we can assume the inferred solar oxygen abundance to be stable across the solar cycle, but that this effect may be significant for other, more active stars. + oai:arXiv.org:2601.15919v1 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/publicdomain/zero/1.0/ - Yi-Long Duan, Tuohuniyazi Tuniyazi, Gang Guo + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + A. G. M. Pietrow, M. Baratella, I. V. Ilyin, M. Steffen, K. G. Strassmeier - Modified hadronic interactions in 3-dimensional simulations - https://arxiv.org/abs/2601.12422 - arXiv:2601.12422v1 Announce Type: new -Abstract: We present a method to test the impact of ad-hoc modifications of some of the generic parameters of hadronic interactions -- cross section, elasticity, and multiplicity -- on any observable quantity using full 3-dimensional simulations of extensive air showers induced by ultra-high-energy cosmic rays. Our approach not only extends the existing 1-dimensional tools to three dimensions, but also introduces more flexible features to better respond to the needs of both theory and experiment. We first thoroughly validate the \conexD framework for the simulation of both longitudinal and lateral features of air showers, in particular for a non-standard configuration of the framework in which different energy thresholds for modifications are applied. Moreover, we show that the implementations of the ad-hoc modifications in this configuration are consistent with the previous one-dimensional simulations. Lastly, we discuss the importance of studying the interaction modifications in three dimensions and the effects of parallel modifications of multiple parameters. - oai:arXiv.org:2601.12422v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Out-of-Sample Validation of MagNet + https://arxiv.org/abs/2601.15926 + arXiv:2601.15926v1 Announce Type: new +Abstract: Machine learning is starting to be used in almost every industry and academic research, and solar physics is no exception. A newly developed machine learning model named MagNet helps us to tackle some of the most serious challenges in data mining by generating transverse fields of solar active regions. Being trained on line-of-sight magnetograms from Michelson Doppler Imager at Solar and Heliospheric Observatory (SOHO/MDI), H{\alpha} maps from Big Bear Solar Observatory and Kanzelhohe Solar Observatory and vector magnetograms from Helioseismic and Magnetic Imager at Solar Dynamic Observatory (SDO/HMI), this model provides vector magnetograms in active regions for SOHO/MDI data covering the strong solar cycle 23. In this study, we performed out-of-sample validation of the MagNet model with data from Imaging Vector Magnetograph (IVM) at Mees Solar Observatory, which was not included in the training process. Our results show good correlation between the AI generated data and the observed vector magnetograms and therefore strengthen the confidence of implementing MagNet to the entire SOHO/MDI archive and future scientific analysis of the AI generated data. + oai:arXiv.org:2601.15926v1 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Ji\v{r}\'i Bla\v{z}ek, Jan Ebr, Jakub V\'icha, Eva dos Santos, Tanguy Pierog, Ralf Ulrich + Aryiadna Yesmanchyk, Yan Xu, Jason T. L. Wang, Haodi Jiang, Chunhui Xu, Haimin Wang - A long-term multiwavelength study of the flat spectrum radio quasar OP 313 - https://arxiv.org/abs/2601.12474 - arXiv:2601.12474v1 Announce Type: new -Abstract: The Flat Spectrum Radio Quasar OP 313 is a high-redshift (z = 0.997) blazar that entered an intense gamma-ray active phase from November 2023 to March 2024, as observed by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. We present a multiwavelength analysis covering 15 years of data, from August 2008 to March 2024, to contextualize this period of extreme gamma-ray activity within the long-term emission of the source. We analyzed a long-term, comprehensive, multiwavelength dataset from different facilities and projects from radio to gamma-rays. We identified the 7 most intense gamma-ray flaring periods and performed a kinematic analysis of Very Long Baseline Array (VLBA) data to determine whether new jet components emerged before or during these flares. For 2 of these flaring periods, we performed the modeling of the spectral energy distribution (SED). The VLBA-BU-BLAZAR and MOJAVE datasets reveal a new jet component appearing in both visibility datasets prior to the onset of one of the strongest gamma-ray flares. By comparing the timing of the VLBA-BU-BLAZAR knots ejection with the gamma-ray flaring periods, we constrained the setup of the SED modeling. We also found that the first gamma-ray flaring period is less Compton-dominated than the others. Our results suggest that the recent activity of OP 313 is triggered by new jet components emerging from the core and interacting with a standing shock. The {\gamma}-ray emission likely arises from dusty torus photons upscattered via Inverse Compton (IC) by relativistic jet electrons. The SED modeling indicates that this component is less dominant during the first {\gamma}-ray flaring period than the later ones. - oai:arXiv.org:2601.12474v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Hot and cloudy: High temperature clouds in super-Earths and sub-Neptunes + https://arxiv.org/abs/2601.15927 + arXiv:2601.15927v1 Announce Type: new +Abstract: JWST observations provide for the first time evidence for an atmosphere on a rocky exoplanet - 55 Cnc e. The atmosphere of 55 Cnc e is hot with $\text{T}_{\text{eq}}>2000$K and shows strong variability, for which cloud formation above a molten crust could be one possible explanation. The composition of the atmosphere of 55 Cnc e is still unknown but suggests the presence of volatiles. We have run cloud formation models on a grid of N-dominated, O-dominated, C-dominated and H-dominated atmospheres to investigate which type of cloud we could expect on hot super-Earths and hot sub-Neptunes ($1000$K $<$ T $<$ $3000$K). Our models combine radiative transfer with equilibrium chemistry of the gaseous and condensed phases, vertical mixing of condensable species, sedimentation, nucleation and coagulation. We find that the condensability of species is highly dependent on the oxygen abundance of an atmosphere. Oxygen poor atmospheres can be heated by UV and optical absorbers PS, TiO and CN which create temperature inversions. These inhibit condensation. Oxygen rich atmospheres are colder without temperature inversions, and are therefore more favourable environments for cloud formation. The major expected cloud component in O-dominated atmospheres with solar refractory abundance is TiO$_2$(s). Spectral features of clouds in these worlds are stronger in transmission than in emission, in particular at short wavelengths. We find a lack of optical data of solid species in comparison to the variety of stable cloud components which can form on hot, rocky planets. + oai:arXiv.org:2601.15927v1 + astro-ph.EP + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Chiara Bartolini, Elina Lindfors, Andrea Tramacere, Marcello Giroletti, Davide Cerasole, Ivan Agudo, Emmanouil Angelakis, Elisabetta Bissaldi, Fausto Casaburo, Filippo D'Ammando, Leonardo Di Venere, Vandad Fallah Ramazani, Federica Giacchino, Fracesco Giordano, Mark Gurwell, Jenni Jormanainen, Svetlana Jorstad, Garrett Keating, Pouya M. Kouch, Alexander Kraus, Anne Lahteenmaki, Serena Loporchio, Nicola Marchili, Alan Marscher, Ioannis Myserlis, Ramprasad Rao, Simona Righini, Merja Tornikoski + http://creativecommons.org/publicdomain/zero/1.0/ + Leoni J. Janssen, Yamila Miguel, Michiel Min, Helong Huang, Mantas Zilinskas, Christiaan P. A. van Buchem - Evidence of energy conversion in weakly collisional plasma during an interplanetary coronal mass ejection - https://arxiv.org/abs/2601.12476 - arXiv:2601.12476v1 Announce Type: new -Abstract: Intervals of enhanced turbulent fluctuations are typically less frequent within the magnetic cloud region of an interplanetary coronal mass ejection (ICME). We investigate two such intervals inside an ICME observed by the \textit{Wind} spacecraft on 8--9 June 2000 and characterize their associated wave populations. We focus on spectral analysis and plasma instability analysis, using ion-scale normalized magnetic helicity and polarization properties with respect to the background magnetic field $B_0$. In the first interval, the ion-scale normalized magnetic helicity shows a left-handed circularly polarized signature. In the second interval, the left-handed signature persists and an additional high-frequency right-handed population appears. The propagation is approximately parallel to $B_0$. The left-handed fluctuations are compatible with Alfv\'en ion-cyclotron (AIC) waves, while the right-handed fluctuations are consistent with fast magnetosonic/whistler (FM/W) waves. The ICME plasma accesses resonance conditions that support multiple ion-scale wave modes. Evolving anisotropies in the plasma and the approach to marginal stability allow the coexistence of AIC-like and fast-magnetosonic/whistler-like fluctuations, with enhanced electron heating favoring the growth of the FM/W contribution and strengthening the density--magnetic-field magnitude correlation. - oai:arXiv.org:2601.12476v1 - astro-ph.SR - physics.plasm-ph - Wed, 21 Jan 2026 00:00:00 -0500 + Enhancing Thermal Sunyaev-Zel'dovich Analyses with Digital Twins of the Local Universe + https://arxiv.org/abs/2601.15935 + arXiv:2601.15935v1 Announce Type: new +Abstract: The thermal Sunyaev-Zel'dovich (tSZ) effect provides a powerful probe of the thermal pressure of ionised gas in galaxy clusters and the cosmic web; constrained simulations reconstruct the mass and velocity fields of the local Universe. We explore how these two may be mutually informative: the tSZ signal provides a benchmark for assessing the fidelity of constrained simulations, and constrained simulations contribute information on the positions, total masses and density profiles of cosmic web structures for use in tSZ studies. We focus on cluster predictions in the Bayesian Origin Reconstruction from Galaxies (BORG) paradigm, introducing CSiBORG-Manticore, a new state-of-the-art suite of digital twins -- data-constrained posterior simulations whose initial conditions are inferred via Bayesian forward modelling. We develop a framework for scoring constrained simulations on their ability to match measured Compton-$y$ maps from Planck for cluster cutouts, and use it to demonstrate improvement from previous BORG reconstructions. We further validate halo masses against weak-lensing-calibrated X-ray masses from eROSITA. We also show how high-fidelity digital twins offer a practical route to extracting additional information from tSZ data through a novel calibration of the mass-observable relation, and provide a complementary framework to purely statistical analyses of Compton-$y$ maps. This paves the way for integrating the large-scale structure information inherent in constrained simulations into the study of CMB secondary anisotropies. + oai:arXiv.org:2601.15935v1 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Omkar Dhamane, Anil Raghav, Simone Benella, Kishor Kumbhar, Raffaella D'Amicis, Oreste Pezzi, Utkarsh Sharma, Ashok Silwal, Panini Maurya, Mirko Stumpo, Kalpesh Ghag, Ajay Kumar, Mohit Shah, Mariyam Karari, Lynn B. Wilson III, Jia Huang, Daniele Telloni + Richard Stiskalek, Harry Desmond - Observational Signatures of Planetary Tidal Disruption Events Around Solar-Mass Stars - https://arxiv.org/abs/2601.12501 - arXiv:2601.12501v1 Announce Type: new -Abstract: The tidal disruption of planets by their host stars represents a growing area of interest in transient astronomy, offering insights into the final stages of planetary system evolution. We model the hydrodynamic evolution and predict the multi-wavelength observational signatures of planetary TDEs around a solar-mass host, focusing on Jupiter-like and Neptune-like progenitors and examining how different eccentricities of the planet's pre-disruption orbit shape the morphology and emission of the tidal debris.We perform 2D hydrodynamic simulations using the FARGO3D code to model the formation and viscous evolution of the resulting debris disk. We employ a viscous alpha-disk prescription and include a time-dependent energy equation to compute the disk's effective temperature and subsequently derive the bolometric and multi-band photometric light curves.Our simulations show that planetary TDEs produce a diverse range of luminous transients. A Jupiter-like planet disrupted from a circular orbit at the Roche limit generates a transient peaking at $L_{bol} \approx 10^{38}$ erg s$^{-1}$ after a 12-day rise. In contrast, the same planet on an eccentric orbit (e=0.5) produces a transient of comparable peak luminosity but on a much shorter timescale, peaking in only 1 day and followed by a highly volatile light curve. We find that the effect of eccentricity is not universal, as it accelerates the event for Jupiter but delays it for Neptune. A robust "bluer-when-brighter" colour evolution is a common feature as the disk cools over its multi-year lifetime. The strong dependence of light curve morphology on the initial orbit and progenitor mass makes these events powerful diagnostics. This framework is crucial for identifying planetary TDEs in time-domain surveys. - oai:arXiv.org:2601.12501v1 + A 2 au resolution view by ALMA of the planet-hosting WISPIT 2 disk + https://arxiv.org/abs/2601.15948 + arXiv:2601.15948v1 Announce Type: new +Abstract: We present deep, high spatial resolution interferometric observations of 0.88 mm continuum emission from the TYC 5709-354-1 system, hereafter WISPIT 2, obtained with the goal of detecting circumplanetary emission in the vicinity of the newly discovered WISPIT 2b planet. Observations with the most extended baseline configuration offered by ALMA, achieving an angular resolution of $25 \times 17$ mas ($3.3 \times 2.2$ au), revealed a single, narrow ring with a deprojected radius of 144.4 au and width of 7.2 au, and no evidence of circumplanetary emission within the cavity. Injection and recovery tests demonstrate that these observations can rule out point-like emission at the location of WISPIT 2b brighter than $\approx 45$ $\mu$Jy at the $3\sigma$ level. While these data can rule out PDS 70c like circumplanetary emission, the upper limit is consistent with empirical mass-flux relationships extrapolated from the stellar regime. Visibility modeling of the continuum ring confirms that WISPIT 2b lies significantly interior to the mm dust ring, raising doubts about the ability of WISPIT 2b to be the only driver of the dust structure. Possible solutions include either another lower mass companion, residing between WISPIT 2b and the cavity edge, likely in the gap seen by SPHERE at $\sim130$ au, or that WISPIT 2b is either substantially more massive than IR-photometry based estimates ($\sim15$ $M_{\rm Jup}$) or on a moderately eccentric orbit. The combination of observations sensitive to the gas and dust distributions on larger spatial scales and dedicated hydrodynamical modeling will help differentiate between scenarios. + oai:arXiv.org:2601.15948v1 astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Mat\'ias Montesinos, Sergei Nayakshin, Vardan Elbakyan, Zhen Guo, Mario Sucerquia, Amelia Bayo, Zhaohuan Zhu + Stefano Facchini, Pietro Curone, Myriam Benisty, Francesco Zagaria, Richard Teague, Gabriele Cugno, Jaehan Bae - Nuclear astrophysics - https://arxiv.org/abs/2601.12508 - arXiv:2601.12508v1 Announce Type: new -Abstract: Reactions between atomic nuclei are measured in great detail in terrestrial laboratory experiments; transferring and extrapolating this knowledge to how the same reactions act within cosmic environments presents major challenges. Cross-disciplinary efforts are needed in view of the many nuclear reactions that govern the chemical evolution of the universe, and occur in a broad range of stellar plasma conditions that require astrophysical exploration. Since the early identification of 'processes' of nucleosynthesis, new insights have been obtained on the complexity of nuclear reaction mechanisms. We use 12C induced capture and fusion processes to illustrate the challenge of low-energy measurements and of using theoretical methods to extrapolate measurements towards energy regimes within cosmic sources. Particle beam experiments at accelerator facilities above and deep underground simulate stellar reactions, new experimental facilities and methods complement these, and this is further complemented by improved theoretical tools to calculate the quantum effects of nuclear reactions at the various cosmic conditions. Astronomical signatures of cosmic nuclear reactions are deduced from light curves characterizing cosmic explosions through gamma-ray lines and presolar grains to the detection of rare neutrino particles from our Sun to distant cosmic events. High resolution spectroscopy of stars has been expanded to objects measured in the X-ray and the gamma energy range of the electromagnetic spectrum. Astro-seismology and isotopic analysis of meteoritic inclusions provide new tools. Chemical-evolution models describe the complex dynamics during the evolution of galaxies. This article summarizes the experimental and theoretical work, and the broad range of observational tools that test the experimental data and the theoretical interpretation of nuclear processes in the cosmos. - oai:arXiv.org:2601.12508v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: NIRCam Imaging in GOODS-S and GOODS-N + https://arxiv.org/abs/2601.15954 + arXiv:2601.15954v1 Announce Type: new +Abstract: We present the Near Infrared Camera (NIRCam) imaging products of the fifth data release (DR5) of the James Webb Space Telescope (JWST) Advanced Deep Extragalactic Survey (JADES). The JADES survey is one of the most ambitious programs yet conducted on JWST, producing deep infrared imaging and multiobject spectroscopy on the GOODS-S and GOODS-N extragalactic deep fields in order to explore galaxies to the earliest epoch. Here we describe the NIRCam data reduction procedures that result in deep and well-characterized mosaics in up to 18 filters covering 469 arcmin$^2$, with 250 arcmin$^2$ having at least 8 filters of coverage. This release contains the full NIRCam imaging of JADES, over 800 JWST mission hours, as well as co-reductions of 19 other programs in these two premier deep fields. We perform detailed tests on the final data products, thereby characterizing the photometric properties, point-spread function, and astrometric alignment. We release mosaics for individual programs (or epochs, depending on scheduling) and the mosaics combining data from all programs in order to facilitate photometric variability studies and the deepest possible photometry. + oai:arXiv.org:2601.15954v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Roland Diehl, Michael Wiescher + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Benjamin D. Johnson, Brant E. Robertson, Daniel J. Eisenstein, Sandro Tacchella, D\'avid Pusk\'as, Qiao Duan, Zihao Wu, Kevin Hainline, Marcia Rieke, Chris Willott, Christopher N. A. Willmer, James A. A. Trussler, Stacey Alberts, Santiago Arribas, William M. Baker, Andrew J. Bunker, Alex J. Cameron, Stefano Carniani, Courtney Carreira, Phillip A. Cargile, Emma Curtis-Lake, Eiichi Egami, Ryan Hausen, Jakob M. Helton, Zhiyuan Ji, Roberto Maiolino, Pablo G. P\'erez-Gonz\'alez, Pierluigi Rinaldi, Fengwu Sun, Yang Sun, Natalia C. Villanueva, Christina C. Williams, Yongda Zhu - Not so-dark: High resolution HI imaging of J0139+4328 and identification of an optical counterpart - https://arxiv.org/abs/2601.12513 - arXiv:2601.12513v1 Announce Type: new -Abstract: Dark galaxies - systems rich in neutral hydrogen (HI) gas but with no stars - are a common prediction of numerous theoretical models and cosmological simulations. However, the unequivocal identification of such sources in current HI surveys has proven challenging. In this work, we present interferometric follow-up observations with the VLA of a former dark galaxy candidate J0139+4328, originally detected with the single-dish FAST telescope. The improved spatial resolution of the VLA data allow us to identify a faint optical counterpart and characterize the galaxy. Located at a distance of about 31 Mpc, J0139+4328 has a stellar mass of 3 x 10^6 M_Sun and a relatively high gas richness of M_HI/M_star = 18. Despite its high ratio, the galaxy is consistent, within the scatter, with the stellar-to-HI mass relation of HI-selected samples in the literature and with the baryonic Tully-Fisher relation (BTFR), although its kinematic measurement is subject to large uncertainties. This case highlights the potential of modern high-sensitivity HI surveys for detecting low surface brightness, gas-rich galaxies, but underscores the need for careful interpretation of low-resolution HI data, with potentially large centroid errors, and for sufficiently deep optical imaging to ensure robust identification. - oai:arXiv.org:2601.12513v1 + JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: MIRI Coordinated Parallels in GOODS-S and GOODS-N + https://arxiv.org/abs/2601.15955 + arXiv:2601.15955v1 Announce Type: new +Abstract: Medium to ultra-deep mid-infrared imaging surveys with the James Webb Space Telescope (JWST)'s Mid-Infrared Instrument (MIRI) are reframing our view of the early Universe, from the emergence of ultra-red dusty and quiescent galaxies to the epoch of reionization to the first galaxies. Here we present the MIRI coordinated parallels component of the JADES program, which obtained ultra-deep (155 ks) imaging at $7.7 \mu$m over $\sim10$ arcmin$^2$ as well as medium depth ($\sim5-15$ ks) imaging at $7.7, 12.8$, and $15 \mu$m over $\sim36$, 25, and 22 arcmin$^2$, respectively, in the GOODS-S and GOODS-N fields. This paper describes the data reduction, which combines the official JWST Calibration Pipeline with custom steps to optimize flagging of warm/hot pixels and optimize background subtraction. We further introduce a new step to address artifacts caused by persistence from saturating sources. The final, fully reduced JADES/MIRI mosaics are being released as part of JADES Data Release 5, along with prior-based forced photometry using NIRCam detection images, providing critical rest-frame near-infrared and optical constraints on early galaxy populations. + oai:arXiv.org:2601.15955v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Barbara \v{S}iljeg, Elizabeth A. K. Adams, Tom A. Oosterloo, Filippo Fraternali, Kelley M. Hess, Jin-Long Xu, Ming Zhu + Stacey Alberts, Daniel J. Eisenstein, Andrew J. Bunker, Emma Curtis-Lake, Qiao Duan, Kevin Hainline, Ryan Hausen, Jakob M. Helton, Zhiyuan Ji, Benjamin D. Johnson, Jianwei Lyu, Jane Morrison, Pablo G. Perez-Gonzalez, George H. Rieke, Marcia Rieke, Pierluigi Rinaldi, Brant Robertson, Yang Sun, Sandro Tacchella, Christina C. Williams, Christopher N. A. Willmer, Zihao Wu - Magnetic field detections in massive systems at different stages of interaction - https://arxiv.org/abs/2601.12546 - arXiv:2601.12546v1 Announce Type: new -Abstract: Despite the importance of magnetic fields in massive stars, their origin is widely debated and still not well understood. With the mounting evidence for the importance of studying magnetic fields in interacting massive binary and multiple systems, it appears necessary to investigate the presence of magnetic fields in semi-detached systems with ongoing mass transfer, and in contact systems where mass is actively being exchanged. We present an analysis of 53 high-resolution HARPSpol spectropolarimetric observations of a sample of 14 massive binary and multiple systems using the least-squares deconvolution technique. The majority of the studied systems are classified as semi-detached or contact binaries. Definite detections of the presence of a magnetic field are achieved in all studied systems apart from the rather faint system SV Cen, for which only a marginal detection was obtained. The fact that the presence of magnetic fields is detected in all but one of the studied systems strongly suggests that interaction between the system components plays a definite role in the generation of magnetic fields in massive stars. The measured mean longitudinal magnetic field strength for all targets is of the order of a few hundred Gauss to a few kiloGauss. The strongest longitudinal magnetic fields of 4 to 5kG are discovered in the massive O-type triple system MY Ser in both components of the contact binary. kiloGauss-order magnetic fields are also detected in two other systems, V1294 Sco and V606 Cen. It is possible that there is an implication of some system characteristics, such as multiplicity, the mass ratio between the components, and a large fillout factor, on the measured magnetic field strength. Our results for the magnetic field measurements in interacting binaries present the first assessment of the occurrence rate of magnetic fields in a representative sample of such systems. - oai:arXiv.org:2601.12546v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: Photometric Catalog + https://arxiv.org/abs/2601.15956 + arXiv:2601.15956v1 Announce Type: new +Abstract: JADES Data Release 5 (DR5) photometric catalogs and describes the methodologies used for source detection, deblending, photometry, uncertainty estimation, and catalog curation. The catalogs are constructed from 35 space-based imaging mosaics obtained with JWST/NIRCam, JWST/MIRI, HST/ACS, and HST/WFC3, combining approximately 1250 hours of JADES imaging with extensive additional public JWST and HST observations in the GOODS fields. Sources are identified using custom signal-to-noise-based detection and deblending algorithms optimized for the depth, resolution, and complex point-spread-function structure of JWST imaging. Source centroids, shapes, and photometric apertures are determined using a new fast two-dimensional Gaussian regression method applied to detection-image profiles. We provide forced circular-aperture photometry, ellipsoidal Kron photometry, and curve-of-growth measurements for every source in every band. We introduce a new pixel-level regression framework to model photometric uncertainties as a function of aperture size and local mosaic properties, accounting for correlated noise in heterogeneous JWST mosaics. Photometric redshifts are computed using template-based fitting applied to both small-aperture photometry on unconvolved images and Kron photometry on common-PSF mosaics. The JADES DR5 catalogs supersede previous JADES photometric releases, and are publicly released through the Mikulski Archive for Space Telescopes and an interactive web interface. + oai:arXiv.org:2601.15956v1 + astro-ph.GA + astro-ph.CO + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1051/0004-6361/202558337 - S. Hubrig, M. Abdul-Masih, S. P. Jarvinen, A. Cikota, M. Sch\"oller, I. Ilyin, A. Escorza + http://creativecommons.org/licenses/by/4.0/ + Brant E. Robertson (University of California, Santa Cruz), Benjamin D. Johnson (Center for Astrophysics | Harvard and Smithsonian), Sandro Tacchella (Kavli Institute for Cosmology, University of Cambridge), Daniel J. Eisenstein (Center for Astrophysics | Harvard and Smithsonian), Kevin Hainline (Steward Observatory, University of Arizona), Stacey Alberts (Steward Observatory, University of Arizona), Santiago Arribas (Centro de Astrobiolog\'ia), William M. Baker (DARK, Niels Bohr Institute), Andrew J. Bunker (University of Oxford), Alex J. Cameron (University of Oxford), Stefano Carniani (Scuola Normale Superiore, Pisa), Courtney Carreira (University of California, Santa Cruz), Jacopo Chevallard (University of Oxford), Chiara Circosta (Institut de Radioastronomie Millim\'etrique), Emma Curtis-Lake (University of Hertfordshire), A. Lola Danhaive (Kavli Institute for Cosmology, University of Cambridge), Qiao Duan (Kavli Institute for Cosmology, University of Cambridge), Eiichi Egami (Steward Observatory, University of Arizona), Ryan Hausen (The Johns Hopkins University), Jakob M. Helton (Pennsylvania State University), Zhiyuan Ji (Steward Observatory, University of Arizona), Roberto Maiolino (Kavli Institute for Cosmology, University of Cambridge), Pablo G. P\'erez-Gonz\'alez (Centro de Astrobiolog\'ia), D\'avid Pusk\'as (Kavli Institute for Cosmology, University of Cambridge), Marcia Rieke (Steward Observatory, University of Arizona), Pierluigi Rinaldi (Space Telescope Science Institute), Fengwu Sun (Center for Astrophysics | Harvard and Smithsonian), Yang Sun (Steward Observatory, University of Arizona), Hannah \"Ubler (Max-Planck-Institut f\"ur extraterrestrische Physik), James A. A. Trussler (Center for Astrophysics | Harvard and Smithsonian), Natalia C. Villanueva (The University of Texas at Austin), Lily Whitler (Kavli Institute for Cosmology, University of Cambridge), Christina C. Williams (NSF National Optical-Infrared Astronomy Research Laboratory), Christopher N. A. Willmer (Steward Observatory, University of Arizona), Chris Willott (NRC Herzberg), Zihao Wu (Center for Astrophysics | Harvard and Smithsonian), Yongda Zhu (Steward Observatory, University of Arizona) - Analytic Modeling of Tidally Locked Rocky Planet Atmospheres Across Dynamical Regimes - https://arxiv.org/abs/2601.12556 - arXiv:2601.12556v1 Announce Type: new -Abstract: We present a new first-principles analytic approach to interpreting eclipses and phase curves of rocky planets. Observations with JWST have reported nondetections of atmospheres around the majority of hot rocky planets orbiting M dwarfs. However, most of these "bare rock" inferences are based on models that are ill-suited to many currently observable planets, as they were developed for use on cooler, slower-rotating bodies. In particular, these models rely on the weak temperature gradient assumption, in which rotation is neglected and temperature gradients can be simply related to wind speeds. We find that this assumption may not be valid for over 40% of terrestrials observed with JWST, including TRAPPIST-1b, GJ 367b, and TOI-2445b. Our simple new four-box model does not rely on this assumption, and instead allows the heat transport efficiency to be specified or follow scalings derived herein. This method is fast, interpretable, physically motivated, reproduces previous general circulation model results, and can be used as a starting point for more detailed modeling. We observe that the longitudinal temperature structure of tidally locked terrestrials depends strongly on the atmospheric circulation. Considering the applicable range of atmospheric dynamical regimes, we find that a given planet's nightside temperature can plausibly vary by 100s of Kelvin (from detectable to undetectable). Furthermore, a planet's dayside energy balance can display complex behavior, with degeneracies between surface pressure and dayside temperature. Illustrating an application to observations, we find that assumptions about atmospheric dynamics and longitudinal temperature structure can bias atmospheric constraints at the order-of-magnitude level. - oai:arXiv.org:2601.12556v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: Catalogs of inferred morphological properties of galaxies from JWST/NIRCam imaging in GOODS-N and GOODS-S + https://arxiv.org/abs/2601.15957 + arXiv:2601.15957v1 Announce Type: new +Abstract: We present morphological parameters and their uncertainties for all sources detected in JWST/NIRCam imaging in GOODS-N and GOODS-S from the JWST Advanced Deep Extragalactic Survey (JADES) catalogs. We model the surface brightness profiles of these sources with single-component S\'ersic profiles, performing Bayesian inference of galaxy structural parameters. We fit each of the $>10^5$ sources with every available JWST/NIRCam wide-band filter individually, amounting to over 3 million S\'ersic profiles computed. We provide catalogs of this morphological information, building one of the largest extragalactic morphological datasets to date, which we share alongside imaging and photometry from the JADES Data Release 5. With this information, we analyze the rest-frame optical redshift evolution of the effective radius and the surface luminosity density within a radius of 1 kiloparsec, $\Sigma_{\text{1 kpc}}$, for 24,692 galaxies at $z>1$. We find $r_{\text{eff}} \propto (1+z)^{-0.635 \pm 0.013}$ kpc, while $\Sigma_{\text{1 kpc}}$ is relatively constant across time. Additionally, we explore bulge-disk decomposition on a subset of 8,390 galaxies in the JADES deep imaging covering the Hubble Ultra Deep Field, finding the effective radius of the bulge-components to increase marginally with time, whereas the disk-component sizes evolve as $r_{\text{eff,disk}} \propto (1+z)^{-1.091 \pm 0.043}$. Future work modeling multi-component surface brightness profiles will enable further analysis of the morphological evolution of galaxies across cosmic time. + oai:arXiv.org:2601.15957v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Christopher P. Wirth, Diana Powell, Robin Wordsworth + http://creativecommons.org/licenses/by/4.0/ + Courtney Carreira, Brant E. Robertson, A. Lola Danhaive, Zhiyuan Ji, Marcia Rieke, Sandro Tacchella, Natalia C. Villanueva, Christopher N. A. Willmer, Zihao Wu, Yongda Zhu, William M. Baker, Andrew J. Bunker, Alex J. Cameron, Jacopo Chevallard, Emma Curtis-Lake, Qiao Duan, Daniel J. Eisenstein, Kevin Hainline, Ryan Hausen, Benjamin D. Johnson, Roberto Maiolino, Petra Mengistu, D\'avid Pusk\'as, Pierluigi Rinaldi, Yang Sun, James A. A. Trussler, Hannah \"Ubler, Anavi Uppal, Christina C. Williams - Clouds and Chemistry Across the Brown Dwarf T-Y Sequence: Insights from JWST Atmospheric Retrievals - https://arxiv.org/abs/2601.12575 - arXiv:2601.12575v1 Announce Type: new -Abstract: The James Webb Space Telescope (JWST) offers exceptional spectral resolution and wavelength coverage, which are essential for studying the coldest brown dwarfs, particularly Y dwarfs. These objects are at the cold end of the sub-stellar sequence and exhibit atmospheric phenomena such as cloud formation, chemical disequilibrium, and radiative-convective coupling. We examine a curated sample of 22 late-T to Y dwarfs through Bayesian atmospheric retrieval (nested sampling) and supervised machine learning (random forests). Bayesian model comparison indicates that cloud-free models are generally favored for the hottest objects in the sample (T6-T8). Conversely, later-type dwarfs exhibit varying preferences, with both gray-cloud and cloud-free models providing comparable fits. The atmospheric parameters retrieved are consistent across the applied methodologies. Evidence of vertical mixing and disequilibrium chemistry is found in several objects; notably, the Y1 dwarf WISEPAJ1541-22 favors a gray cloud model and shows elevated abundances of both CO and CO2 compared to equilibrium chemistry calculations. As anticipated, the abundances of H2O, CH4, and NH3 increase with decreasing effective temperature over the T-Y sequence. - oai:arXiv.org:2601.12575v1 - astro-ph.SR - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: Wisp Subtraction with the Non-negative Matrix Factorization Algorithm + https://arxiv.org/abs/2601.15958 + arXiv:2601.15958v1 Announce Type: new +Abstract: Wisps are among the most prominent scattered light artifacts in JWST/NIRCam imaging. They often appear in certain regions of the detectors and contaminate observations at surface-brightness levels relevant for faint-source photometry. We introduce a new subtraction method that uses the non-negative matrix factorization (NMF) algorithm to model and remove wisps. Using deep NIRCam observations from the JWST Advanced Deep Extragalactic Survey (JADES) and other programs, we construct multi-component, filter- and detector-specific wisp templates that capture the wisp structures and their exposure-to-exposure morphological variations. Wisps in individual exposures are represented as non-negative linear combinations of these templates, consistent with their additive nature and reducing degeneracies relative to single-template scaling. Compared to existing approaches, our method delivers lower residual root mean square in wisp-affected regions and reduces photometric bias and scatter to levels consistent with clean detector areas. The NMF wisp templates are readily applicable to other datasets and are publicly released to support future NIRCam extragalactic surveys. + oai:arXiv.org:2601.15958v1 + astro-ph.IM + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - A. Lueber, D. Kitzmann, K. Heng + http://creativecommons.org/licenses/by/4.0/ + Zihao Wu, Benjamin D. Johnson, Daniel J. Eisenstein, Phillip Cargile, Kevin Hainline, Ryan Hausen, Pierluigi Rinaldi, Brant E. Robertson, Sandro Tacchella, Christina C. Williams, Christopher N. A. Willmer - On the accuracy of mass and size measurements of young protoplanetary disks - https://arxiv.org/abs/2601.12578 - arXiv:2601.12578v1 Announce Type: new -Abstract: Knowing the masses and sizes of protoplanetary disks is of fundamental importance for the contemporary theories of planet formation. However, their measurements are associated with large uncertainties. In this proof of concept study, we focus on the very early stages of disk evolution, concurrent with the formation of the protostellar seed, because it is then that the initial conditions for subsequent planet formation are likely established. Using three-dimensional hydrodynamic simulations of a protoplanetary disk followed by radiation transfer postprocessing, we constructed synthetic disk images at millimeter wavelengths. We then calculated the synthetic disk radii and masses using an algorithm that is often applied to observations of protoplanetary disks with ALMA, and compared the resulting values with the actual disk mass and size derived directly from hydrodynamic modeling. We paid specific attention to the effects of dust growth on the discrepancy between synthetic and intrinsic disk masses and radii. We find that the dust mass is likely underestimated in Band 6 by factors of 1.4-4.2 when Ossenkopf & Henning opacities and typical dust temperatures are used, but the discrepancy reduces in Band~3, where the dust mass can be even overestimated. Dust growth affects both disk mass and size estimates via the dust-size-dependent opacity, and extremely low values of dust temperature (~ several Kelvin) are required to recover the intrinsic dust mass when dust has grown to mm-sized grains and its opacity has increased. Dust mass estimates are weakly sensitive to the distance to the source, while disk radii may be seriously affected. We conclude that the accuracy of measuring the dust mass and disk radius during the formation of a protoplanetary disk also depends on the progress in dust growth. (Abridged) - oai:arXiv.org:2601.12578v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + JWST Advanced Deep Extragalactic Survey (JADES) Data Release 5: Photometrically Selected Galaxy Candidates at z > 8 + https://arxiv.org/abs/2601.15959 + arXiv:2601.15959v1 Announce Type: new +Abstract: We present a sample of 2081 sources selected at photometric redshift $z_{\mathrm{phot}} > 8$ across the JADES DR5 data release in GOODS-S and GOODS-N over a total area of 469 square arcmin. These sources range from $M_{\mathrm{UV}} = -22$ to $M_{\mathrm{UV}} = -16$, with 19 objects at $z_{\mathrm{phot}} > 14$. We estimate the UV slopes for the full sample from fits to the photometry and find evidence for a steepening of the relationship between the UV continuum slope and $M_{\mathrm{UV}}$ to higher redshifts, a result that differs from prior analyses of brighter samples in the literature. We provide evidence that over one quarter of our sources have evidence for being morphologically extended, with many galaxies showing multiple bright knots or clumps even out to $z \sim 13 - 14$, an indication of how galaxies at Cosmic Dawn are growing and evolving. We discuss JADES-GN+189.15982+62.28899, a GOODS-N F200W dropout galaxy at $z_{\mathrm{phot}} \sim 15 - 18$ which has been observed spectroscopically with JWST/NIRSpec in prism mode, resulting in a very low signal-to-noise spectrum that is consistent with the photometry and rules out a number of low-redshift solutions for the source. Finally, we use a subsample of 123 objects in our sample with spectroscopic redshifts to explore the usage of alternate fitting templates and a prescription for Ly-$\alpha$ damping wing absorption, finding that both produce significant improvements to the estimated photometric redshifts. + oai:arXiv.org:2601.15959v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Eduard I. Vorobyov (University of Vienna, Department of Astrophysics, 1180, Vienna, Austria, Institut f\"ur Astro- und Teilchenphysik, Universit\"at Innsbruck, 6020 Innsbruck, Austria, Research Institute of Physics, Southern Federal University, Rostov-on-Don 344090, Russia), Aleksandr Skliarevskii (Research Institute of Physics, Southern Federal University, Rostov-on-Don 344090, Russia), Vardan Elbakyan (Fakult\"at f\"ur Physik, Universit\"at Duisburg-Essen, D-47057 Duisburg, Germany, Research Institute of Physics, Southern Federal University, Rostov-on-Don 344090, Russia), Michael Dunham (Department of Physics, Middlebury College, Middlebury, VT 05753, USA), Manuel Guedel (University of Vienna, Department of Astrophysics, 1180, Vienna, Austria) + Kevin N. Hainline, Daniel J. Eisenstein, Lily Whitler, Brant Robertson, Benjamin D. Johnson, Peter Jakobsen, David Puskas, Sandro Tacchella, Jakob M. Helton, Zihao Wu, Santiago Arribas, William M. Baker, Andrew J. Bunker, Alex J. Cameron, Stefano Carniani, Courtney Carreira, Stephane Charlot, Jacopo Chevallard, Emma Curtis-Lake, Francesco D'Eugenio, Qiao Duan, Eiichi Egami, Ryan Hausen, Zhiyuan Ji, Tobias J. Looser, Roberto Maiolino, Petra Mengistu, Pablo G. Perez-Gonzalez, Marcia Rieke, Pierluigi Rinaldi, Fengwu Sun, James A. A. Trussler, Hannah Ubler, Christina C. Williams, Christopher N. A. Willmer, Chris Willott, Joris Witstok - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) V: Comparison between scattered light and thermal emission - https://arxiv.org/abs/2601.12586 - arXiv:2601.12586v1 Announce Type: new -Abstract: Debris discs are analogues to our own Kuiper belt around main-sequence stars and are therefore referred to as exoKuiper belts. They have been resolved at high angular resolution at wavelengths spanning the optical to the submillimetre-millimetre regime. Short wavelengths probe the light scattered by such discs, which is dominated by micron-sized dust particles, while millimetre wavelengths probe the thermal emission of millimetre-sized particles. Determining differences in the dust distribution between millimetre- and micron-sized dust is fundamental to revealing the dynamical processes affecting the dust in debris discs. We aim to compare the scattered light from the discs of the ALMA survey to Resolve exoKuiper belt Substructures (ARKS) with the thermal emission probed by ALMA. We focus on the radial distribution of the dust. We used high-contrast scattered light observations obtained with VLT/SPHERE, GPI, and the HST to uniformly study the dust distribution in those systems and compare it to the dust distribution extracted from the ALMA observations carried out in the course of the ARKS project. We also set constraints on the presence of planets by using these high-contrast images combined with exoplanet evolutionary models. 15 of the 24 discs comprising the ARKS sample are detected in scattered light, with TYC9340-437-1 being imaged for the first time at near-infrared wavelengths. For 6 of those 15 discs, the dust surface density seen in scattered light peaks farther out compared to that observed with ALMA. These 6 discs except one are known to also host cold CO gas. Conversely, the systems without significant offsets are not known to host gas, except one. This observational study suggests that the presence of gas in debris discs may affect the small and large grains differently, pushing the small dust to greater distances where the gas is less abundant. - oai:arXiv.org:2601.12586v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + JADES: A Prominent Galaxy Overdensity Candidate within the First 500 Myr + https://arxiv.org/abs/2601.15960 + arXiv:2601.15960v1 Announce Type: new +Abstract: We report a galaxy overdensity candidate at $z\approx 10.5$ in the JWST Advanced Deep Extragalactic Survey (JADES). This overdensity contains 18 galaxies with consistent photometric redshifts and robust F115W dropouts within 8 comoving Mpc in projection. The galaxy number density is four times higher than the field expectation, accounting for one-third of comparably bright galaxies and nearly 50% of the total star formation rate at $10<z_\mathrm{phot}<12$ in the GOODS-S field. Two compact members of the overdensity show potential Balmer breaks suggestive of evolved stellar populations or little red dots (LRDs). One-third of galaxies have close companions or substructures within 1 kpc at consistent photometric redshifts, implying more frequent interactions in an overdense environment. Most galaxies have stellar masses of 0.6-3$\times10^8$ $M_\odot$, half-light radii of $\sim$200 pc, and star formation rates of $\sim$5 $M_\odot \mathrm{yr^{-1}}$, with no significant deviation from typical high-redshift scaling relations. We find tentative evidence for a spatially varying Ly$\alpha$ transmission inferred photometrically, consistent with an emerging ionized bubble. This overdensity provides a rare opportunity for probing the environmental impact on galaxy evolution and the onset of cosmic reionization within the first 500 Myr. + oai:arXiv.org:2601.15960v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.1051/0004-6361/202556523 - Astronomy & Astrophysics, 2024, 705, A199 - J. Milli, J. Olofsson, M. Bonduelle, R. Bendahan-West, J. P. Marshall, E. Choquet, A. A. Sefilian, Y. Han, B. Zawadzki, S. Mac Manamon, E. Mansell, C. del Burgo, J. M. Carpenter, A. M. Hughes, M. Booth, E. Chiang, S. Ertel, Th. M. Esposito, Th. Henning, J. Hom, M. R. Jankovic, A. V. Krivov, J. B. Lovell, P. Luppe, M. A. MacGregor, S. Marino, B. C. Matthews, L. Matr\`a, A. Mo\'or, N. Pawellek, T. D. Pearce, S. P\'erez, V. Squicciarin, P. Weber, D. J. Wilner, M. C. Wyatt + http://creativecommons.org/licenses/by/4.0/ + Zihao Wu, Daniel J. Eisenstein, Benjamin D. Johnson, Kevin Hainline, William M. Baker, Andrew J. Bunker, Alex J. Cameron, Emma Curtis-Lake, A. Lola Danhaive, Ryan Hausen, Jakob M. Helton, Zhiyuan Ji, Tobias J. Looser, Roberto Maiolino, Petra Mengistu, Pierluigi Rinaldi, Brant E. Robertson, Fengwu Sun, Sandro Tacchella, James A. A. Trussler, Christina C. Williams, Christopher N. A. Willmer, Joris Witstok - The DESI Transients Survey: Legacy Classifications and Methodology - https://arxiv.org/abs/2601.12611 - arXiv:2601.12611v1 Announce Type: new -Abstract: We present the first systematic spectroscopic observations of extragalactic transients from the Dark Energy Spectroscopic Instrument (DESI), as part of the DESI Transients Survey program. With 5,000 fibers and an ${\sim} 8$ deg$^2$ field of view, we exploit DESI as a machine for the discovery and classification of transients. We present transient classifications from archival DESI data in Data Releases 1 and 2, relying on a combination of a secondary target program and serendipitous observations. We also present observations from the first 6 months of the DESI spare fiber program dedicated to transients. The program is run in coordination with a dedicated DECam time-domain survey, serving as a pathfinder for what we will be able to achieve in conjunction with the Rubin Observatory Legacy Survey of Space and Time (LSST). We classify over 250 transients, of which the majority were previously unclassified. The sample comprises thermonuclear and core-collapse supernovae and tidal disruption events (TDEs), including a TDE observed before its discovery in imaging. We demonstrate DESI's ability to classify a population of faint transients down to $r\sim 22.5$ mag during main survey operations, with negligible impacts on DESI's main observations. can you make this plain text for arxiv abstarct - oai:arXiv.org:2601.12611v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + JADES: Discovery of Large Reservoirs of Small Dust Grains in the Circumgalactic Medium of Massive Galaxies at $z\sim3.5$ through Deep JWST/NIRCam Imaging and Grism Spectroscopy + https://arxiv.org/abs/2601.15961 + arXiv:2601.15961v1 Announce Type: new +Abstract: Using JWST NIRCam imaging and grism spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES) Origins Fields, we report spectroscopic redshift measurements of 1,445 emission-line galaxies at $z=0-9$. Within this sample, we identify two prominent galaxy protoclusters at $z = 3.47$ and 3.69, each anchored by massive dusty star-forming galaxies (DSFGs). In the vicinity of these systems, we discover seven background galaxies at $z=3.6 - 6$ that simultaneously exhibit strong rest-frame optical emission lines (e.g., [O III] and H$\alpha$) and unusually reddened UV-to-optical continua. We attribute this reddening to dust extinction arising from the circumgalactic medium (CGM) of the foreground DSFGs at projected separations of 7-30 kpc. We infer a high dust column density ($\gtrsim 10^{-1}$ Msun/kpc^2), substantially exceeding those measured in low-redshift halos and those predicted by hydrodynamical simulations like IllustrisTNG and FIRE-2. The steep extinction curves, comparable to or steeper than that of the SMC, indicate a dominant population of small dust grains in the high-redshift CGM. We conclude that DSFGs at this epoch host large reservoirs of dusty CGM enriched to solar metallicity. These extended dust components are largely invisible to (sub-)millimeter interferometers such as ALMA because of their low surface brightness. We discuss the physical processes in dust transport that might be key to reproducing our observations, including galaxy mergers, cool-phase gas outflows, dust shattering, sputtering and radiation pressure. Finally, we caution that foreground CGM dust extinction may redden background galaxies at intermediate redshifts to mimic Lyman-break galaxies at $z\gtrsim10$. + oai:arXiv.org:2601.15961v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xander J. Hall (McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh PA, USA), Antonella Palmese (McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh PA, USA), Segev BenZvi (Department of Physics,Astronomy, University of Rochester, Rochester NY, USA), John Banovetz (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Brendan O'Connor (McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh PA, USA), Lei Hu (McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh PA, USA), Erica Hammerstein (Department of Astronomy, University of California, Berkeley CA, USA, Lawrence Berkeley National Laboratory, Berkeley CA, USA), Ariel Amsellem (McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh PA, USA), Jessica Nicole Aguilar (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Steven Ahlen (Department of Physics, Boston University, Boston MA, USA), Steven Bailey (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Davide Bianchi (Universita degli Studi di Milano,INAF Osservatorio Astronomico di Brera, Milano, Italy), David Brooks (Department of Physics,Astronomy, University College London, London, UK), Todd Claybaugh (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Andrei Cuceu (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Kyle Dawson (Department of Physics,Astronomy, University of Utah, Salt Lake City UT, USA), Axel de la Macorra (Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Mexico), John Della Costa (Department of Astronomy, San Diego State University, San Diego CA, USA, NSF NOIRLab, Tucson AZ, USA), Arjun Dey (NSF NOIRLab, Tucson AZ, USA), Peter Doel (Department of Physics,Astronomy, University College London, London, UK), Simone Ferraro (Lawrence Berkeley National Laboratory,University of California, Berkeley CA, USA), Andreu Font-Ribera (Institut de Fisica d'Altes Energies, Barcelona, Spain), Jaime E. Forero-Romero (Departamento de Fisica,Observatorio Astronomico, Universidad de los Andes, Bogota, Colombia), Enrique Gaztanaga (Institute of Cosmology,Gravitation, University of Portsmouth, UK, Institut d'Estudis Espacials de Catalunya, Barcelona, Spain), Satya Gontcho A Gontcho (Lawrence Berkeley National Laboratory, Berkeley CA, USA, University of Virginia, Charlottesville VA, USA), Alma Xochitl Gonzalez-Morales (Departamento de Fisica, Universidad de Guanajuato, Guanajuato, Mexico), Or Graur (Institute of Cosmology,Gravitation, University of Portsmouth, UK), Gaston Gutierrez (Fermi National Accelerator Laboratory, Batavia IL, USA), Mustapha Ishak (Department of Physics, University of Texas at Dallas, Richardson TX, USA), Jorge Jimenez (Institut de Fisica d'Altes Energies, Barcelona, Spain), Dick Joyce (NSF NOIRLab, Tucson AZ, USA), Stephanie Juneau (NSF NOIRLab, Tucson AZ, USA), Anthony Kremin (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Ofer Lahav (Department of Physics,Astronomy, University College London, London, UK), Claire Lamman (The Ohio State University, Columbus OH, USA), Martin Landriau (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Laurent Le Guillou (Sorbonne Universite,CNRS IN2P3 LPNHE, Paris, France), Alexie Leauthaud (Department of Astronomy,Astrophysics, University of California, Santa Cruz CA, USA), Michael Levi (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Marc Manera (Departament de Fisica, Universitat Autonoma de Barcelona,Institut de Fisica d'Altes Energies, Bellaterra, Spain), Aaron Meisner (NSF NOIRLab, Tucson AZ, USA), Ramon Miquel (Institut de Fisica d'Altes Energies,Institut Catalana de Recerca i Estudis Avancats, Barcelona, Spain), John Moustakas (Department of Physics,Astronomy, Siena University, Loudonville NY, USA), Adam Myers (Department of Physics,Astronomy, University of Wyoming, Laramie WY, USA), Seshadri Nadathur (Institute of Cosmology,Gravitation, University of Portsmouth, UK), Will Percival (Department of Physics,Astronomy, University of Waterloo,Perimeter Institute for Theoretical Physics, Waterloo ON, Canada, Waterloo Centre for Astrophysics, Waterloo ON, Canada), Claire Poppett (Lawrence Berkeley National Laboratory,Space Sciences Laboratory, University of California, Berkeley CA, USA), Ignasi Perez-Rafols (Departament de Fisica, Universitat Politecnica de Catalunya, Barcelona, Spain), Francisco Prada (Instituto de Fisica Teorica UAM CSIC, Universidad Autonoma de Madrid, Madrid, Spain, Instituto de Astrofisica de Andalucia, Granada, Spain, Instituto de Astrofisica de Canarias, Tenerife, Spain), Graziano Rossi (Department of Physics,Astronomy, Sejong University, Seoul, Republic of Korea), Eusebio Sanchez (CIEMAT, Madrid, Spain), Edward Schlafly (Space Telescope Science Institute, Baltimore MD, USA), David Schlegel (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Michael Schubnell (Department of Physics, University of Michigan, Ann Arbor MI, USA), David Sprayberry (NSF NOIRLab, Tucson AZ, USA), Gregory Tarle (University of Michigan, Ann Arbor MI, USA), Benjamin Alan Weaver (NSF NOIRLab, Tucson AZ, USA), Rongpu Zhou (Lawrence Berkeley National Laboratory, Berkeley CA, USA), Hu Zou (National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China) + http://creativecommons.org/publicdomain/zero/1.0/ + Fengwu Sun, Daniel J. Eisenstein, Francesco D'Eugenio, Kevin Hainline, Jakob M. Helton, Benjamin D. Johnson, Xiaojing Lin, Marcia Rieke, Brant Robertson, Sandro Tacchella, Andrew J. Bunker, Jacopo Chevallard, Emma Curtis-Lake, Eiichi Egami, Ryan Hausen, Zhiyuan Ji, Jianwei Lyu, Roberto Maiolino, Pierluigi Rinaldi, Yang Sun, James A. A. Trussler, Christina C. Williams, Christopher N. A. Willmer, Joris Witstok, Zihao Wu, Yongda Zhu - LAMOST J113208.06-005052.3 and LAMOST J052957.56+344127.0: two new binaries with a hot white dwarf and a flaring companion star - https://arxiv.org/abs/2601.12647 - arXiv:2601.12647v1 Announce Type: new -Abstract: Binaries contain rich physical information, and the study of binaries has always been a hot topic in stellar physics research. The stars LAMOST J1132 and LAMOST J0529 have not yet been recorded in the SIMBAD astronomical database. We have investigated their physical properties via methods such as spectral analysis, photometric analysis, and light curve analysis. Based on comprehensive analysis, we conclude that they are two newly discovered binary systems, each consisting of a hot white dwarf and a flaring companion star. Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra indicate that both stars contain hot white dwarfs. The spectral fitting yields $T_{eff}$=53728$\pm$2467\,K, log$g$=7.98$\pm$0.08 for LAMOST J1132, and $T_{eff}$=47381$\pm$494\,K, log$g$=7.84$\pm$0.05 for LAMOST J0529. The weak neutral metal lines in the LAMOST spectra and the discrepancy between the Global Astrometric Interferometer for Astrophysics (GAIA) and LAMOST spectra both indicate that these two sources are likely binary systems. The relatively high flux values for both sources in the near-infrared and mid-infrared bands support our preliminary judgment. The color index in the near-infrared bands suggests that the companion star is K or M type for LAMOST J1132 and M type for LAMOST J0529. Light curve data from the Zwicky Transient Facility (ZTF) indicate that the companion stars of both sources are stars exhibiting flare activity. The eclipse probability is very low, indicating that these two sources are non-eclipsing binary systems. The physics of binaries is fascinating, and future data from LAMOST Medium Resolution Spectra are expected to enable the detection of magnetic fields in these two hot white dwarfs. - oai:arXiv.org:2601.12647v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Undermassive Hosts of $z = 4-6 $ AGN from JWST/NIRCam Image Decomposition with CONGRESS, FRESCO, and JADES + https://arxiv.org/abs/2601.15962 + arXiv:2601.15962v1 Announce Type: new +Abstract: In the local Universe, supermassive black hole (SMBH) masses strongly correlate with their host-galaxies' stellar masses ($M_{*}$), but galaxies hosting faint AGN recently found by JWST may deviate from this relation. To constrain the M$_{\text{BH}}$-M$_{*}$ relation at high redshift, we performed AGN-host image decomposition for 17 low-luminosity AGN galaxies at $z$\,$\sim$\,4--6 using NIRCam images in the JADES GOODS-N field. These sources are identified as AGNs from broad H$\alpha$ emission lines detected by the CONGRESS and FRESCO surveys. We used \textsc{galfit+MCMC} to fit spatial profiles in 7 wide-band images and detected extended emission in 9 sources out of 17. The close spatial alignment between the extended components and the AGN centers indicates that this emission likely originates from the host galaxies. These sources are extended at 0.9--2.0~$\mu$m, suggesting significant host-galaxy light in the rest-frame UV. For the sources with the host detection, the stellar mass inferred based on image decomposition result can be 1-2 dex lower than the results without image decomposition. The BH-to-stellar mass ratio spans $M_{\text{BH}}/M_\ast$\,$\sim$\,0.01--1.48, placing them well above the local $M_{\text{BH}}$--$M_\ast$ relation. In contrast, the host-galaxy size--mass relation broadly agrees with previous measurements. Our results suggest that the host galaxies of these faint AGN are either genuinely under-massive compared to their black hole masses, or too compact to be spatially resolved. + oai:arXiv.org:2601.15962v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Zheng Ma, Eichi Egami, Yongda Zhu, Fengwu Sun, Jianwei Lyu, Junyu Zhang, Christopher N. A. Willmer, Andrew J. Bunker, Stefano Carniani, Emma Curtis-Lake, Ryan Hausen, Xihan Ji, Zhiyuan Ji, Ignas Juod\v{z}balis, Roberto Maiolino, George H. Rieke, Pierluigi Rinaldi, Yang Sun, Sandro Tacchella, Hannah \"Ubler, Christina C. Williams + + + There Is More to Outshining: 2D Dust Effects on Stellar Mass Estimates at $3 \leq z < 9$ with JWST in the JADES Field + https://arxiv.org/abs/2601.15963 + arXiv:2601.15963v1 Announce Type: new +Abstract: Dust attenuation modifies the observed spectral energy distribution (SED), leading to biases in the properties inferred from integrated SED fitting. As spatially resolved SED modeling becomes feasible for large high-redshift samples, it is increasingly important to assess how dust attenuation affects resolved mass estimates. We evaluate the impact of dust attenuation on stellar mass estimates derived from integrating spatially resolved SED fitting results. We perform spatially resolved and integrated SED fitting on a sample of 3408 galaxies at $3 \leq z < 9$ from the GOODS South field, combining deep NIRCam from the JWST Advanced Deep Extragalactic Survey (JADES) and HST/ACS imaging from GOODS and CANDELS. We compare galaxy-integrated properties derived from fitting the summed SED with those obtained from spatially resolved SED modeling. Using a two-component dust attenuation model with a variable slope, we investigate how the dust attenuation slope, A(V), and stellar population properties contribute to discrepancies in the resulting stellar mass estimates. Resolved stellar masses are systematically higher than integrated estimates, with a median offset of +0.24 dex. Resolved analyses recover higher dust attenuations ($\Delta A(V)\approx +0.08$ mag), lower birth cloud fractions ($\Delta\mu \approx -0.28$), and grayer attenuation curves ($\Delta\delta_{\mathrm{ISM}} = +0.08$), arising from preferential sampling of compact star-forming regions. Integrated fits underestimate stellar ages by $\sim23\%$ at $z < 5$ and 31$\%$ at $z \gtrsim 5$. The stellar mass offset correlates strongly with the age difference and the attenuation slope difference, indicating that age-dependent outshining and spatially varying dust geometry are primary drivers of the discrepancy between resolved and integrated stellar masses. + oai:arXiv.org:2601.15963v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yanhui Chen, Chaomi Duan, Baokun Sun + M. Hamed, P. G. P\'erez-Gonz\'alez, M. Annunziatella, L. Colina, I. Shivaei, M. Perna, A. J. Bunker, K. Ma{\l}ek, S. Arribas, J. \'Alvarez-M\'arquez, C. N. A. Willmer, H. \"Ubler, R. Bhatawdekar, J. Chevallard, E. Curtis-Lake, Z. Ji, P. Rinaldi, C. C. Williams - PyIRD: A Python-Based Data Reduction Pipeline for Subaru/IRD and REACH - https://arxiv.org/abs/2601.12669 - arXiv:2601.12669v1 Announce Type: new -Abstract: PyIRD is a Python-based pipeline for reducing spectroscopic data obtained with IRD (InfraRed Doppler; Kotani et al. (2018)) and REACH (Rigorous Exoplanetary Atmosphere Characterization with High dispersion coronagraphy; Kotani et al. (2020)) on the Subaru Telescope. It is designed to process raw images into one-dimensional spectra in a semi-automatic manner. Unlike traditional methods, it does not rely on IRAF (Tody, 1986; 1993), a software used for astronomical data reduction. This approach simplifies the workflow while maintaining efficiency and accuracy. Additionally, the pipeline includes an updated method for removing readout noise patterns from raw images, enabling efficient extraction of spectra even for faint targets such as brown dwarfs. - The code is open source and available at https://github.com/prvjapan/pyird . - oai:arXiv.org:2601.12669v1 - astro-ph.IM - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + JADES: Evolution of nitrogen abundances in star-forming galaxies from z ~ 1.5-7 + https://arxiv.org/abs/2601.15964 + arXiv:2601.15964v1 Announce Type: new +Abstract: We present nitrogen abundance measurements based on the low-ionisation [NII]6583 emission line for 588 galaxies between 1.5<z<7.0 from the JWST Advanced Deep Extragalactic Survey (JADES). We detect the temperature-sensitive [OIII]4363 auroral line in 40 galaxies in our sample, affording $T_e$-based abundances for this subset. We find that the average N/O abundance ratio in our low-metallicity sample is at least 0.1 dex higher than z ~ 0 samples. In particular, we find significant scatter toward high N/O, with five galaxies being identified with enhanced nitrogen abundances (log(N/O)>-1.1) at low-metallicity (12+log(O/H)<8.0) from $T_e$-based measurements. Meanwhile, applying strong-line abundance measurements to the remainder of our sample reveals a further 14 candidate galaxies passing these abundance cuts, implying that around 13 % of 12+log(O/H)<8.0 galaxies at these redshifts are nitrogen-enhanced at this level. We find that N/O abundance in low-metallicity systems correlates with SFR, surface density of SFR, and surface density of stellar mass at high redshift, while only in high-metallicity systems does a correlation with stellar mass emerge. Despite healthy representation of these `moderately nitrogen-enhanced' galaxies (-1.1<log(N/O)<-0.6), no galaxies in our low-metallicity sample are identified as having log(N/O)>-0.6, abundances that are typical of high-redshift NIII]- and NIV]-emitters. This demonstrates that the extreme nitrogen enhancements seen in some NIII]- and NIV]-emitters are only attained during the most extreme starbursts. This suggests that these elevated abundances are caused by enrichment from young massive stars in extreme environments and that the impact of this enrichment pathway is milder, though still important, for high-redshift systems on the star-forming main sequence. + oai:arXiv.org:2601.15964v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - 10.21105/joss.09126 - Journal of Open Source Software, 11(117), 9126 (2026) - Yui Kasagi, Hajime Kawahara, Ziying Gu, Teruyuki Hirano, Takayuki Kotani, Masayuki Kuzuhara, Kento Masuda + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Alex J. Cameron, Courtney Carreira, Charlotte Simmonds, Andrew J. Bunker, Aayush Saxena, Stefano Carniani, St\'ephane Charlot, Jacopo Chevallard, Emma Curtis-Lake, Kevin Hainline, Ryan Hausen, Xihan Ji, Zhiyuan Ji, Benjamin D. Johnson, Pierluigi Rinaldi, Brant Robertson, Jan Scholtz, Maddie S. Silcock, Sandro Tacchella, James A. A. Trussler, Hannah \"Ubler, Christina C. Williams, Christopher N. A. Willmer, Chris Willott, Joris Witstok - Rate of Repeating Tidal Disruption Events with 5--19 years interval constrained by CRTS and ZTF - https://arxiv.org/abs/2601.12691 - arXiv:2601.12691v1 Announce Type: new -Abstract: Statistics on tidal disruption events (TDEs) may be contaminated by repeating TDEs (rTDEs), which have been extensively discovered recently. However, the origin of rTDEs remains unclear. In addition, no statistical research on rTDEs with time intervals $>5$ years has been made yet. In this work, we searched for rTDEs with time intervals of 5--19 years using CRTS data in a sample of 16 ZTF BTS TDEs at $z<0.05$. We found 2 rTDE candidates, AT 2019azh and AT 2024pvu, with time intervals of 13.2 and 17.1 years, respectively. The peak luminosities of CRTS flares are close to those of ZTF flares. For the CRTS flare of AT 2024pvu, using GALEX UV observations near the peak, we measured a blackbody temperature of $\sim19500$ K, consistent with TDEs and higher than SNe. Moreover, we estimated the expected number of SNe in the sample to be $\lesssim0.08$, and hence the probability that both CRTS flares are SNe is only 0.3\%. Therefore, the possibility that both CRTS flares are SNe can be ruled out, and it is likely that both are TDEs. Using the two rTDEs, we inferred that the TDE rate is 2--3 orders of magnitude higher than the average over 5--19 years prior to TDE detection. Considering another two rTDEs with intervals of $\sim$2 years in the sample and possible rTDEs missed by CRTS, rTDEs with intervals of $<20$ years may account for 25\%--60\% of the TDE sample. We prefer to explain rTDEs as repeating partial TDEs, but the possibility of independent TDEs cannot be ruled out and requires future observational tests. - oai:arXiv.org:2601.12691v1 - astro-ph.HE + Clump-like Structures in High-Redshift Galaxies: Mass Scaling and Radial Trends from JADES + https://arxiv.org/abs/2601.15965 + arXiv:2601.15965v1 Announce Type: new +Abstract: Massive star-forming clumps are a prominent feature of high-redshift galaxies and are thought to trace gravitational fragmentation, feedback, and bulge growth in gas-rich disks. We present a statistical analysis of clump-like structures in $\sim$3600 galaxies spanning $2 \lesssim z \lesssim 8$ from deep JWST/NIRCam imaging in the JADES GOODS--South field. Clumps are identified as residual features after subtracting smooth S\'ersic profiles, enabling a uniform, rest-frame optical census of sub-galactic structure. We characterize their physical properties, size--mass relations, and spatial distributions to constrain models of sub-galactic structure formation and evolution. We find that clumps in our sample are typically low-mass ($10^{\sim7-8}M_\odot$), actively star-forming, and show diverse gas-phase metallicity, dust attenuation, and stellar population properties. Their sizes and average pairwise separations increase with cosmic time (toward lower redshift), consistent with inside-out disk growth. The clump mass function follows a power law with slope $\alpha = -1.50_{-0.17}^{+0.19}$, consistent with fragmentation in turbulent disks. We find a deficit of relatively young clumps near galaxy centers and a radial transition in the size--mass relation: outer clumps exhibit steeper, near-virial slopes ($R_{\rm e}\propto M_*^{\sim 0.3}$), while inner clumps follow flatter trends ($R_{\rm e}\propto M_*^{\sim 0.2}$), consistent with structural evolution via migration or disruption. These results provide new constraints on the formation, survival, and dynamical evolution of clumps, highlighting their role in shaping galaxy morphology during the peak of cosmic star formation. + oai:arXiv.org:2601.15965v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Yujun Yao, Luming Sun, Tao Wu, Ning Jiang, Shiyan Zhong, Xinwen Shu + Yongda Zhu, Marcia J. Rieke, Zhiyuan Ji, Andrew J. Bunker, Courtney Carreira, A. Lola Danhaive, Qiao Duan, Eiichi Egami, Daniel J. Eisenstein, Kevin Hainline, Benjamin D. Johnson, Zheng Ma, D\'avid Pusk\'as, George H. Rieke, Pierluigi Rinaldi, Brant Robertson, Sandro Tacchella, Hannah \"Ubler, Natalia C. Villanueva, Christina C. Williams, Christopher N. A. Willmer, Zihao Wu, Junyu Zhang + + + Gaia20fnr: A binary-lens microlensing event with full orbital motion revealed by four space telescopes + https://arxiv.org/abs/2601.15969 + arXiv:2601.15969v1 Announce Type: new +Abstract: The microlensing event Gaia20fnr is a long-duration, non-caustic-crossing binary-lens event at high Galactic latitude. Triggered by a photometric rise detected by the Gaia space mission, the event was followed up with observations from multiple ground-based facilities and four space telescopes: Gaia, NEOWISE, Swift, and TESS. We characterize the Gaia20fnr microlensing system by determining the physical and orbital properties of the binary lens, the nature of the luminous source, and the kinematics of both the source and the lens. We employed a binary-lens microlensing model including full Keplerian orbital motion and annual microlens parallax to fit the photometric data. The event is best explained by a K2 giant source at $D_{\rm S} = 3.10 \pm 0.10\,\mathrm{kpc}$ lensed by a stellar binary composed of $M_{\rm L,1} = 0.46 \pm 0.06\,M_\odot$ and $M_{\rm L,2} = 0.52 \pm 0.06\,M_\odot$ at a distance of $D_{\rm L} = 0.54 \pm 0.05\,\mathrm{kpc}$. The light curve exhibits strong signatures of orbital motion and requires a full Keplerian model with a period of $P = 0.67 \pm 0.04\,\mathrm{yr}$ and a radial-velocity semi-amplitude of $K_1 = 16.9 \pm 0.9\,\mathrm{km\,s^{-1}}$. Gaia20fnr is one of the few microlensing events for which a complete Keplerian binary-lens solution has been derived. The model can be tested with follow-up radial-velocity and high-resolution imaging observations as well as forthcoming Gaia DR4 and DR5 astrometric time-series data. Its long duration, multi-peak structure, and extensive coverage make it a benchmark for studying faint nearby low-mass binaries through microlensing. + oai:arXiv.org:2601.15969v1 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + M. Wicker, {\L}. Wyrzykowski, M. Hundertmark, K. A. Rybicki, P. Zieli\'nski, E. Stonkut\.e, N. Ihanec, M. Maskoli\=unas, E. Bachelet, K. Kruszy\'nska, M. Dominik, D. A. H. Buckley, I. Gezer, P. Miko{\l}ajczyk, K. Kotysz, J. Majumdar, E. Pak\v{s}tien\.e, J. Zdanavi\v{c}ius, V. \v{C}epas, U. Jonauskait\.e, V. Bozza, A. Cassan, R. Figuera Jaimes, M. Rabus, P. Rota, R. A. Street, Y. Tsapras, J. Wambsganss, S. Awiphan, S. M. Brincat, Z. Budzik, J. W. Davidson Jr., R. Dymock, C. Galdies, V. Godunova, F. -J. Hambsch, M. Jab{\l}onska, T. Kvernadze, M. Larma, M. Makowska, Y. Markus, J. Merc, O. Michniewicz, M. Motylinski, A. Popowicz, M. Radziwonowicz, D. Reichart, A. O. Simon, P. Trzcionkowski, M. Zejmo, S. Zola - Optical Continuum Light Curves and Bolometric Energy Estimates of Solar White-light Flares - https://arxiv.org/abs/2601.12709 - arXiv:2601.12709v1 Announce Type: new -Abstract: Solar white-light flares (WLFs) are solar flares exhibiting enhanced emission in the optical continuum. They are critical for understanding energy release and transport mechanisms in solar flares and for conducting comparative studies with stellar WLFs. However, the scarcity of accurately and reliably measured optical continuum light curves for solar WLFs significantly hampers related studies. Based on the optimized solar WLF identification method, we construct a dataset of optical continuum light curves for 70 solar WLFs using 6173 {\AA} continuum intensity images from the Solar Dynamics Observatory. Moreover, for each solar WLF event, we also provide the location of the white-light emission enhancement signals and key parameters including bolometric energies and durations derived from both the traditional fixed-temperature blackbody model and the refined variable-temperature blackbody model. This dataset will serve as a valuable resource for future statistical investigations of solar WLFs and for comparative studies between solar and stellar flares. - oai:arXiv.org:2601.12709v1 + HE0144-4657: A Carbon-Enhanced Ultra Metal-Poor Star ([Fe/H] ~ -4.1) from the Helmi Stream Disrupted Dwarf Galaxy + https://arxiv.org/abs/2601.15974 + arXiv:2601.15974v1 Announce Type: new +Abstract: We present the discovery of HE0144-4657, an ultra metal-poor, CNO-enhanced star dynamically associated with the Helmi Stream disrupted dwarf-galaxy remnant. This star was first identified as a carbon-enhanced, metal-poor star candidate from the Hamburg/ESO objective-prism survey, then followed up with medium- and high-resolution spectroscopy. At [Fe/H]=-4.11, HE0144-4657 is the lowest metallicity star found in a stellar stream to date. Its chemistry is consistent with field halo stars in the same metallicity regime, and the light-element (atomic number Z<=30) chemical abundance pattern suggests that HE0144-4657 is a bona-fide second-generation star with a possible Population III progenitor in the 50Msun mass range with low explosion energy. One possible scenario for the origin of HE0144-4657 is that it was formed in an ultra-faint dwarf galaxy accreted by the Helmi Stream progenitor system before merging with the Milky Way. This discovery provides further evidence for the extragalactic origin of carbon-enhanced ultra metal-poor stars in the Milky Way and for the specific environments conducive to their formation. + oai:arXiv.org:2601.15974v1 + astro-ph.GA astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yingjie Cai, Yijun Hou, Hengkai Ding, Ting Li, Jifeng Liu + Vinicius M. Placco, Guilherme Limberg, Catherine R. Kennedy, Norbert Christlieb - Discovery of Multiple Ultra-Broad-Velocity Molecular Features Associated with the W44 Molecular Cloud - https://arxiv.org/abs/2601.12728 - arXiv:2601.12728v1 Announce Type: new -Abstract: We report the discovery of multiple compact molecular features exhibiting extremely broad velocity widths toward the W44 molecular cloud. ALMA CO $J$=3--2 data reveal eight ``Petit--Bullets'' surrounding the previously known ``Bullet.'' Each Petit--Bullet shows a distinct V-shaped structure in position--velocity space, reminiscent of the Y-shaped morphology of the Bullet, suggesting a common origin. These features are interpreted as the result of high-velocity plunges of compact gravitational objects into dense molecular gas. The spatial and kinematic properties of the Petit--Bullets suggest that the plunging material was not a single object but rather a small cluster of compact bodies. A virial mass of $1.0\!\times\! 10^{5}\, M_\odot$ inferred from their velocity dispersion is comparable to that of typical globular clusters. Momentum analysis further implies that the main Bullet likely formed by an isolated black hole. These findings provide new evidence for dynamical interactions between halo clusters and disk molecular gas. - oai:arXiv.org:2601.12728v1 + Extreme line profile variations in the repeating changing-look active galactic nucleus IRAS23226-3843 + https://arxiv.org/abs/2601.15979 + arXiv:2601.15979v1 Announce Type: new +Abstract: IRAS23226-3843 has been identified as a highly variable Seyfert galaxy and even as a changing-look active galactic nucleus based on optical spectra. Here we present follow-up observations - taken over the past five years - for examining the ongoing photometric and spectral variations in this remarkable galaxy. We carried out SWIFT observations of IRAS23226-3843 together with new optical spectra taken in 2023 and 2024. In parallel we investigate ASAS-SN photometric data from 2014 till 2025. IRAS23226-3843 stayed on a high continuum flux level in the X-ray as well as in the optical since a historic outburst in 2019. However, it shows strong short-term variations on timescales of a few months. Densely sampled ASAS-SN V-band continuum data from 2014 till 2025 confirm that behavior. IRAS23226-3843 switched from a clear Seyfert 1 type in December 2019 to a Seyfert 1.9/2 type in July 2020 based on its optical spectra. Afterward, it again became a Seyfert 1 type with symmetric broad single-peaked Balmer line profiles in January 2023. These spectra prove the repeating changing-look character of the galaxy.IRAS23226-3843 exhibits extreme high Balmer decrements Ha\Hb based on their broad line components. The Balmer decrement values are on the order of 10. IRAS23226-3843 successively showed all types of broad line Balmer profiles during the past 25 years over periods of many years: asymmetric single-peaked, double-peaked, as well as single-peaked and symmetric profiles in addition to its Seyfert 1.9/2 transition. These variations are not clearly correlated with continuum and line intensity variations. + oai:arXiv.org:2601.15979v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Momoko Makita, Tomoharu Oka, Shiho Tsujimoto, Tatsuya Kotani + 10.1051/0004-6361/202558093 + Wolfram Kollatschny, Dirk Grupe, Hartmut Winkler, Malte A. Probst, Martin W. Ochmann, Amon Poenitzsch, Norbert Schartel, Salem Wolsing, Stefanie Komossa, Stephen B. Potter - Non-adiabatic Effect on Convective Mode - https://arxiv.org/abs/2601.12756 - arXiv:2601.12756v1 Announce Type: new -Abstract: The systematic analysis of non-adiabatic effect on convective mode has been conducted using wave energy relation. In the adiabatic analysis, the "propagation diagram" for convective mode is proposed as a useful tool to see its behavior. In the non-adiabatic analysis, it is found that for strongly non-adiabatic case, a monotonically growing convective mode becomes oscillatory. In this phase, the radial displacement and the distribution of wave energy show only one bump, in which the distribution of entropy energy eS almost overlaps with the distribution of gravity energy eg. Entropy energy eS seems to act as potential energy of oscillatory convection. In addition to this, this change occurs not gradually, but abruptly with change of non-adiabatic indicator. - oai:arXiv.org:2601.12756v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + A multi-wavelength approach of AGN feedback in LINERs: The case of NGC 4438 + https://arxiv.org/abs/2601.15991 + arXiv:2601.15991v1 Announce Type: new +Abstract: The presence of multi-phase outflows in low ionisation nuclear emission-line regions (LINERs) has been confirmed to be frequent, but the mechanisms that launch them are still under study. We aim to explore the connections between the ionised gas outflow, radio continuum structures and X-ray emission detected in the LINER NGC4438. We analyse L, C and X-band images (from 1.4 to 12 GHz) of the LINER NGC4438, combining high-resolution data from enhanced Multi Element Radio Linked Interferometer Network (e-MERLIN) and Karl G Jansky Very Large Array (VLA). We produce radio flux, spectral index maps, and an energetic model that allows us to characterise the source. We incorporate optical integral field spectroscopy (IFS) data (GTC/MEGARA) and Chandra X-ray data, with comparable resolution, to better trace the outflow, the AGN and their potential connection. We present new L, C, and X-band high-resolution, high-sensitivity radio images and spectral-index maps that probe $\sim$ 25 pc scales in NGC 4438. These data reveal a close morphological correspondence between the radio structures and the ionised gas bubble. Using a spatially resolved energetic model based on radio flux and spectral index, we disentangle the compact AGN emission from the extended bubble for the first time, establishing their distinct physical origins. We measure a kinetic power of $\sim 5\times 10^{44}$ erg s$^{-1}$ for the radio bubble, exceeding the power of the ionised outflow by more than three orders of magnitude. Our multi-wavelength analysis indicates that NGC 4438 is undergoing jet-mode feedback, where a low-luminosity, weakly collimated jet impacts the dense northern interstellar medium. This interaction drives shock-ionised gas, produces a moderate velocity outflow that removes material from the region, and generates thermal X-ray emission coincident with the radio and H$\alpha$ cavity. + oai:arXiv.org:2601.15991v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Hiroyasu Ando + M. Puig-Subir\`a, J. Mold\'on, I. M\'arquez, J. Masegosa, O. Gonz\'alez-Mart\'in, L. Hermosa Mu\~noz, S. Cazzoli, D. Williams-Baldwin - The Feasibility of Potentially Hazardous Asteroids Flybys Using Multiple Venus Gravity Assists - https://arxiv.org/abs/2601.12759 - arXiv:2601.12759v1 Announce Type: new -Abstract: This work develops low-energy spacecraft (SC) trajectories using Venus gravity assists to study asteroids during heliocentric transfer segments between planetary encounters. The study focuses on potentially hazardous asteroids (PHAs) as primary exploration targets. This paper proposes a method for calculating SC trajectories that enable asteroid flybys after a Venus gravity assist. The method involves formulating and solving an optimization problem to design trajectories incorporating flybys of selected asteroids and Venus. Trajectories are calculated using two-body dynamics by solving the Lambert problem. A preliminary search for candidate asteroids uses an algorithm to narrow the search space of the optimization problem. This algorithm uses the V-infinity globe technique to connect planetary gravity assists with resonant orbits. The resonant orbit in this case serves as an initial approximation for the SC's trajectory between two successive planetary flybys. Four flight schemes were analyzed, including multiple flybys of Venus and asteroids, with the possibility of an SC returning to Earth. The proposed solutions reduce flight time between asteroid approaches, increase gravity assist frequency, and enhance mission design flexibility. The use of Venus gravity assists and resonant orbits ensures a close encounter with at least one asteroid during the SC's trajectory between two consecutive flybys of Venus, and demonstrates the feasibility of periodic Venus gravity assists and encounters with PHAs. The developed method was applied to construct trajectories that allow an SC to approach both Venus-resonant asteroids and PHAs via multiple Venus gravity assists. An additional study was carried out to identify asteroids accessible during the Earth-Venus segment in launch windows between 2029 and 2050. - oai:arXiv.org:2601.12759v1 - astro-ph.EP - astro-ph.IM - physics.space-ph - Wed, 21 Jan 2026 00:00:00 -0500 + SVOM discovery of a strong X-ray outburst of the blazar 1ES~1959+650 and multi-wavelength follow-up with the Neil Gehrels Swift observatory + https://arxiv.org/abs/2601.15994 + arXiv:2601.15994v1 Announce Type: new +Abstract: On December 6, 2024, 1ES 1959+650, one of the X-ray brightest blazars known, underwent a high-amplitude X-ray outburst detected by SVOM, the first such discovery with this mission. The source was subsequently monitored with SVOM and Swift from December 2024 to March 2025. We report the detection and multi-wavelength follow-up of this event, and describe the temporal and spectral evolution observed during the campaign. Data from SVOM/MXT, SVOM/ECLAIRs, and Swift/XRT were analyzed with log-parabola models to track flux and spectral variability. The source was detected in a bright state over the 0.3-50 keV range. During the three months of monitoring, the X-ray flux varied significantly, showing episodes of spectral hardening at high flux levels. The spectral curvature evolved more irregularly and did not show a clear trend with flux. A shift of the Spectral Energy Distribution (SED) synchrotron peak to higher energies is seen when the flux increases. This constitutes the first blazar outburst discovered in X-rays by SVOM. The coordinated follow-up with Swift provided continuous coverage of the flare and highlights the strong complementarity of the two missions for time-domain studies of blazars. The flare shows no clear signatures of either Fermi I or Fermi II acceleration, suggesting a mixed Fermi I/II scenario. + oai:arXiv.org:2601.15994v1 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.1016/j.actaastro.2026.01.016 - Acta Astronautica. 2026. V. 241. P. 504-528 - Vladislav Zubko + http://creativecommons.org/licenses/by/4.0/ + A. Foisseau, A. Coleiro, S. Komossa, D. Grupe, F. Cangemi, P. Maggi, D. G\"otz, H. -B. Cai, B. Cordier, N. Dagoneau, Z. -G. Dai, Y. -W. Dong, M. Fernandes Moita, O. Godet, A. Goldwurm, H. Goto, S. Guillot, L. Huang, M. -H. Huang, N. Jiang, C. Lachaud, S. Le Stum, E. -W. Liang, X. -M. Lu, L. Michel, C. Plasse, Y. L. Qiu, J. Rodriguez, L. Tao, S. Schanne, J. Wang, X. -G. Wang, X. -Y. Wang, J. Wei, C. Wu, Y. -W. Yu, J. Zhang, L. Zhang, S. -N. Zhang, S. Zheng - Testing Red Clump Models with the Asteroseismic Binary KIC 10841730 - https://arxiv.org/abs/2601.12773 - arXiv:2601.12773v1 Announce Type: new -Abstract: Binaries in which both stars are pulsating are rare but extremely valuable. We present the first study of an asteroseismic binary system consisting of a core helium-burning red clump (RC) star and a red giant branch (RGB) star. The Kepler target KIC 10841730 is a wide binary (period $2917 \pm 8$ d) that provides ideal conditions to test the accuracy of RC models. While prior studies of RC stars have revealed discrepancies in modelling the period spacings of mixed modes, other model parameters remain largely untested. We perform a detailed modelling analysis using individual mode frequencies and cover a large parameter space in mass, metallicity, He-abundance, mixing length, overshooting, and mass-loss, and we also explore different methods to correct for surface effects. We find two possible results for the red clump models. One solution requires introducing an unexpected offset of the phase shift in the red clump model, yielding an age consistent with the companion star and current masses of $1.01 \pm 0.06$ and $1.08 \pm 0.06$ M$_\odot$ for the RC and RGB star, respectively. Alternatively, we find that excluding the identification of two questionable radial modes resolves the phase-shift offset issue but results in a higher mass and thus a much younger age for the red clump star, contradicting the age obtained from its companion. We conclude that uncertainties in red clump models affect not only the g-mode period spacings but also the properties of the p modes. We show the power of asteroseismic binaries in validating and constraining stellar models and highlight the need for refining red-clump models. - oai:arXiv.org:2601.12773v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Spatially resolved stellar-to-total dynamical mass relation: Radial variations, gradients and profiles of galaxy stellar populations + https://arxiv.org/abs/2601.16019 + arXiv:2601.16019v1 Announce Type: new +Abstract: Although galaxy evolution is governed by the interplay between baryonic physics and dark matter halo assembly, how halo properties shape observed galaxies remains unclear. With current challenges in measuring halo properties, the stellar-to-total dynamical mass relation is introduced as an alternative metric sensitive to the dark matter content within galaxies. We explore how spatially resolved stellar population properties vary across this relation using optical IFS data and photometry from 265 CALIFA galaxies. Spatially resolved ages and metallicities, [M/H], are derived using a Bayesian framework fed with a library of model spectra based on stochastic star formation and metallicity histories and dust attenuation. We study these properties in terms of both stellar and total dynamical mass, with the latter being enclosed mass within three effective radii from Jeans dynamical modeling. We find that ages and [M/H] measured at different annuli depend on both stellar and total mass, yet showing distinct radial trends. While the dependence of age on total mass is more prominent in the outskirts, that of [M/H] is significant in the inner parts. This behavior is reflected in the stellar population profiles and gradients, more strongly for age and connected to morphology. Intermediate-mass early-types have higher stellar-to-total mass ratios and flatter age profiles with older ages, and steep negative [M/H] profiles, whereas later-types have lower stellar-to-total mass ratios, negative age profiles with younger ages and shallower negative [M/H] profiles. Moreover, at fixed stellar mass galaxies have more negative age gradients and shallower [M/H] ones as total mass increases. Our results show that total dynamical mass is linked to systematic variations in stellar populations and radial gradients at fixed stellar mass, suggesting a relevant role of dark matter halos in shaping galaxy properties + oai:arXiv.org:2601.16019v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Lea S. Schimak, Timothy R. Bedding, Courtney L. Crawford, Paul G. Beck, Yaguang Li, Daniel Huber, Joel Ong, Benjamin T. Montet, May Gade Pedersen, Desmond H. Grossmann, Savita Mathur, Rafael A. Garc\'ia + L. Scholz-Diaz, A. R. Gallazzi, S. Zibetti, D. Mattolini - Classical Be Stars and Classical Be Star Binaries from LAMOST DR12 - https://arxiv.org/abs/2601.12789 - arXiv:2601.12789v1 Announce Type: new -Abstract: Classical Be (CBe) stars are rapidly rotating B-type stars with Balmer emission lines that originated from the decretion disks surrounding them in their spectra. Accounting for $\sim$20% of all B-type stars, most CBe stars are thought to form through mass and angular momentum transfer from their companions. It follows that in most close CBe star binaries, the companions are expected to be post-main-sequence stars rather than main-sequence (MS) stars. Hitherto, $\sim$100 CBe star binaries have been identified, the majority of which are Be/X-ray binaries. As expected, none of the others have indeed been confirmed as CBe+MS binary stars. To further study and verify the origin of CBe stars, identifying additional CBe star binaries is indispensable. In this study, we report 504 CBe stars identified using data from Data Release 12 of the Large sky Area Multi-Object fiber Spectroscopic Telescope. Among these, 141 are newly identified and 14 exhibiting radial velocity variations are identified as CBe star binaries. Besides, 60 CBe stars with high normalized unit weight error (RUWE) but not confirmed by dynamics are proposed as potential CBe star binaries. We also find that 34 CBe stars are potential cluster members. By calculating peculiar velocities, 37 runaway stars are identified with peculiar velocities ranging from $\sim$40 km s$^{-1}$ to $\sim$101 km s$^{-1}$. - oai:arXiv.org:2601.12789v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Modeling the Impact of Unresolved Stellar Companions on Detection Sensitivity in Kepler's Small Planet Occurrence Rates + https://arxiv.org/abs/2601.16031 + arXiv:2601.16031v1 Announce Type: new +Abstract: Unresolved stellar companions can cause both under-estimations in the radii of transiting planets and over-estimations of their detectability, affecting our ability to reliably measure planet occurrence rates. To quantify the latter, we identified a control sample of 198 Kepler stars with sensitivity to Earth-like planets if they were single stars, and imaged them with adaptive optics. In 20% of systems, we detected stellar companions that were close enough to go unresolved in Kepler observations. We calculated the distribution of planet radius correction factors needed to adjust for these observed companions, along with simulations of undetected companions to which our observations were not sensitive. We then used these correction factors to optimize an occurrence rate model for small close-in planets while correcting Kepler's detection efficiency for the presence of unresolved companions, and quantified how this correction affects occurrence estimates. Median occurrence rates for small planets between $2-100$ days increased by an average factor of $1.08-1.19$ (depending on statistical treatments), with the largest differences found for smaller planets at larger orbital periods. We found that the frequency of Earth-sized planets in the habitable zone ($\eta_\oplus$) increased by a factor of ${1.18}_{-0.66}^{+0.43}-{1.46}_{-0.83}^{+0.53}$ when accounting for the effect of unresolved companions on Kepler's detection sensitivity. + oai:arXiv.org:2601.16031v1 + astro-ph.EP + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Qian-Yu An, Wei-Min Gu, Zhi-Xiang Zhang + http://creativecommons.org/licenses/by/4.0/ + Galen J. Bergsten, David R. Ciardi, Jessie L. Christiansen, Catherine A. Clark, Ilaria Pascucci, Courtney D. Dressing, Kevin K. Hardegree-Ullman, Michael B. Lund - Identification of false positive double-lined spectroscopic binaries in LAMOST-MRS data due to moonlight contamination - https://arxiv.org/abs/2601.12824 - arXiv:2601.12824v1 Announce Type: new -Abstract: We present a method for identifying false positive double-lined spectroscopic binary (SB2) candidates by analysing medium-resolution survey spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR10. Specifically, we focus on spectra contaminated by moonlight, which exhibit near-zero radial velocity (RV) and solar-like spectral lines from the secondary component. By applying strict constraints on the contamination parameters and fitting the contaminated spectra, we ultimately confirmed that 126 false positive binaries are single stars contaminated by moonlight. Additionally, we identify several key factors contributing to moonlight contamination: the lunar phase during observation, the G-band magnitude of the star, and the angular distance between the star and the moon. Notably, artificial satellites in low-orbital can also introduce contamination from solar-like spectral components, but they typically display significantly higher transverse velocities. In a follow-up study, we will expand our analysis to identify additional false positive SB2 systems and systematically classify them according to their contamination sources. - oai:arXiv.org:2601.12824v1 - astro-ph.SR - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Unveiling the Spectral Morphological Division of Fast Radio Bursts with CHIME/FRB Catalog 2 + https://arxiv.org/abs/2601.16048 + arXiv:2601.16048v1 Announce Type: new +Abstract: Fast radio bursts (FRBs) are commonly divided into repeating and apparently non-repeating sources, but whether these represent distinct physical populations remains uncertain. In this work, we apply an unsupervised machine learning methods combining Uniform Manifold Approximation and Projection (UMAP) with density-based clustering to analyze CHIME/FRB Catalog 2. We find that FRBs remain primarily separated into two clusters in the multi-dimensional parameter space, with a recall of 0.94 for known repeaters, indicating strong robustness. Consistent with Catalog 1 analyses, we confirm that the spectral morphology parameter, specifically spectral running remains the key discriminator between the two populations, indicating that narrowband emission is an intrinsic and persistent property of repeating FRBs. With the enlarged Catalog 2 sample, we further identify a stable subclass of atypical repeaters (about $6\%$ of repeating bursts) that are broadband, shorter in duration, and more luminous, resembling non-repeating bursts. The Nonrepeater-like cluster also shows higher inferred energies and dispersion measures, consistent with a scenario in which apparently non-repeating FRBs may result from observational incompleteness, with low-energy repeating bursts remaining undetected. Our results provide new statistical evidence for a physical connection between repeating and non-repeating FRBs. + oai:arXiv.org:2601.16048v1 + astro-ph.HE + astro-ph.CO + gr-qc + hep-ph + hep-th + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1093/mnras/staf531 - Monthly Notices of the Royal Astronomical Society, Vol. 539, No. 4, June 2025, pp. 3506-3517 - Zhoulin Wang, Mikhail Kovalev, Jianping Xiong, Yanjun Guo, Xuefei Chen + Wan-Peng Sun, Yin-Long Cao, Yong-Kun Zhang, Ji-Guo Zhang, Xiaohui Liu, Yichao Li, Fu-Wen Zhang, Wan-Ting Hou, Jing-Fei Zhang, Xin Zhang - Project FOSSO I: Fates of the Known BDs in MS-BD Binaries - https://arxiv.org/abs/2601.12861 - arXiv:2601.12861v1 Announce Type: new -Abstract: Context. Understanding the survival and orbital evolution of brown dwarf (BD) companions during the post-main-sequence (MS) evolution of their host stars is increasingly important, especially with recent discoveries of many substellar companions around white dwarfs (WDs). Aims. We investigate the long-term evolution and final outcomes of BDs orbiting low-mass MS stars as these evolve into WDs. By comparing forward-modeling populations with observed WD-BD binaries, we test evolutionary models and predict the existence of yet-undetected systems. Methods. We employ the COMPAS binary population synthesis code to evolve observed MS-BD systems through the post-MS phases of their host stars into the WD stage, tracking orbital changes driven by mass loss, tides, and common-envelope (CE) evolution. Results. Our simulations reproduce a period gap in the distribution of detached WD-BD binaries, consistent with observations. We also identify a boundary separating detached and semi-detached systems on the period-mass diagram, located at orbital periods of $\sim$1-2 hours depending on the BD mass. Conclusions. We predict that a subset of currently known MS-BD binaries will survive post-MS evolution and emerge as detached WD-BD systems, while others will undergo CE evolution and potentially form cataclysmic variables with BD donors. Our results reproduce the observed period gap in WD-BD binaries and provide quantitative predictions for the role of CE efficiency in shaping their distribution. This work predicts that many WD-BD systems remain undetected, motivating targeted searches with microlensing and high-contrast imaging techniques using next-generation large telescopes. - oai:arXiv.org:2601.12861v1 - astro-ph.SR - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Constraining Nuclear Molecular Gas Content with High-resolution CO Imaging of GOALS Galaxies + https://arxiv.org/abs/2601.16057 + arXiv:2601.16057v1 Announce Type: new +Abstract: We present measurements of the cool molecular gas mass around the nuclei of two gas-rich mergers, III Zw 035 and IRAS F01364-1042, whose enclosed masses (M$_\mathrm{enc}$) within the central 40-80 pc would be overmassive if attributed entirely to the supermassive black hole mass (SMBH) and compared to SMBH-galaxy scaling relations. Our gas mass measurements are derived from Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 long-baseline observations of CO(J=2-1) and 230 GHz continuum emission at 14-20 pc resolution, which probes below the resolving limit of the previous black hole mass measurements. Subtracting molecular gas mass from these enclosed masses is not enough to reconcile with BH-galaxy relationships, but independently measuring M$_\mathrm{enc}$ using the cold CO(2-1) gas does shift the black holes down to their expected values. Still, these ALMA data reveal respective molecular gas masses of $\sim$3$\times$10$^7$ to $\sim$6$\times$10$^8$ M$_\odot$ within 70 pc of these black holes, which could challenge some black hole accretion models that assume nuclear gas like this has no angular momentum. + oai:arXiv.org:2601.16057v1 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Zhangliang Chen, Hongming Jin, Hongwei Ge, Cong Yu, Kejun Wang, Dichang Chen, Bo Ma + James Agostino, Anne M. Medling, Loreto Barcos-Mu\~noz, Vivian U, Mynor Rodr\'iguez V\'asquez, George C. Privon, Claudia Cicone, Lee Armus, Jorge Moreno, Claudio Ricci, Yiqing Song, Christopher C. Hayward, Katherine Alatalo, David B. Sanders - Exploring rotational properties and the YORP effect in asteroid families - https://arxiv.org/abs/2601.12972 - arXiv:2601.12972v1 Announce Type: new -Abstract: The long-term dynamical evolution of asteroid families is governed by the interplay between orbital and rotational evolution driven by thermal forces and collision. We aim to observationally trace the rotational evolution of main-belt asteroid families over Gyr timescales. We analyzed rotational properties of 8739 asteroids with spin period measurements and 3794 asteroids with obliquity determinations across 28 asteroid families spanning ages from 14~Myrs to 3~Gyrs. We introduced a dimensionless timescale that normalizes each asteroid's family age by its classical YORP timescale, enabling direct comparison of rotational states across different evolutionary stages. We examined two key observables: the fraction of slow rotators (periods greater than or equal to 30 hours) and the polarization fraction (the degree to which asteroid spin poles align correctly with their position in the family's V-shape distribution according to the Yarkovsky theory). Evolution of both quantities were fitted to identify characteristic transition timescales. We discovered that the slow-rotator fraction increases steeply with $t$ and saturates at $f_{\rm slow} \simeq 0.25$ around a breakpoint $t_{\rm bp} \simeq 20$. This implies a stochastic YORP timescale $\tau_{\rm YORP,stoc} \simeq 10\,\tau_{\rm YORP}$ by comparison with rotational evolution models that include tumbling and weakened YORP torques. The polarization fraction reaches a maximum of $\simeq 0.8$ at $t \simeq 16$ and then decays toward the random limit $f_{\rm pol} \rightarrow 0.5$ for $t \gtrsim 20$, indicating an increasing dominance of collisional spin reorientation over time. The rotation properties within different asteroid families offer crucial clues to rotation evolution and can serve as a new dimension for age estimation of asteroid families with more data in the LSST era. - oai:arXiv.org:2601.12972v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Formation and X-ray emission from hot bubbles in planetary nebulae - III. The impact of [Wolf-Rayet]-type winds + https://arxiv.org/abs/2601.16100 + arXiv:2601.16100v1 Announce Type: new +Abstract: We use radiation-hydrodynamical simulations to investigate the formation and synthetic X-ray emission of hot bubbles within planetary nebulae (PNe) driven by the powerful winds of H-deficient, [Wolf-Rayet]([WR])-type stars. Our models, based on {\sc mesa} stellar evolution tracks for 1--3 M$_{\odot}$ progenitors, adopt a recent mass-loss rate prescription for [WR] stars and incorporate the enhanced radiative cooling of their C-rich material, comparing the results against standard H-rich PN models. The enhanced mass-loss in the [WR] models leads to an accelerated post-AGB evolution and a subsequent delay in hot bubble formation compared to their H-rich counterparts, as suggested by a previous work. By computing synthetic X-ray spectra that account for the mixed H-rich and H-deficient gas phases, we find that models incorporating [WR] winds exhibit significantly higher X-ray luminosities ($L_\mathrm{X}$) than their H-rich counterparts, but the emissivity-weighted plasma temperature of the X-ray-emitting gas converge to values of $T_\mathrm{X} = [1-3] \times 10^{6}$~K, regardless of whether the system follows a [WR]-type or an H-rich post-AGB evolutionary path. Our results reinforce previous suggestions that mixing is a key mechanism in generating the observed soft X-ray emission even for PN hosting [WR] central stars. + oai:arXiv.org:2601.16100v1 + astro-ph.SR + astro-ph.GA + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Gabriele Bertinelli, Wen-Han Zhou, Paolo Tanga + Rogelio Orozco-Duarte, Jes\'us A. Toal\'a, S. Jane Arthur, Janis B. Rodr\'iguez-Gonz\'alez, Luke Conmy, Rolf Kuiper - Joint analysis of small-scale galaxy clustering and galaxy--galaxy lensing from BOSS galaxies - https://arxiv.org/abs/2601.12976 - arXiv:2601.12976v1 Announce Type: new -Abstract: We present a joint analysis of galaxy clustering and galaxy--galaxy lensing measurements from BOSS galaxies using a simulation-based emulation method combined with a halo occupation distribution model. Our emulators are constructed with the Aemulus $\nu$ simulations, a suite of $w\nu$CDM $N$-body simulations with massive neutrinos as independent particle species. We combine small-scale analysis of clustering from $0.1h^{-1}$Mpc to $60.2~h^{-1}$Mpc and lensing from $1.7h^{-1}$Mpc to $60.2~h^{-1}$Mpc to perform cosmological constraints. We split the BOSS galaxies into three redshift bins to measure their clustering and employ galaxies from Dark Energy Camera Legacy Survey and Hyper Suprime-Cam as source galaxies to measure lensing separately. We find that the addition of lensing significantly improves the constraining power on $S_{8}=\sigma_8(\Omega_m/0.3)^{0.5}$, with a weak improvement for $f\sigma_{8}$. Our results of $f\sigma_{8}$ indicate tensions of around $1\sim4\sigma$ below the results of CMB observations of Planck. For $S_{8}$, our results are also lower than Planck, and the tension can be mitigated when considering possible systematics in lensing measurement. As a byproduct, our analysis prefers a non-zero neutrino mass but without strong significance, with the constraining power dominated by the clustering. Given the accuracy and precision of our model and the observational data, it is anticipated that larger and higher-quality spectroscopic datasets will improve the constraints on this fundamental property in the near future. - oai:arXiv.org:2601.12976v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + Cis--Trans Rotational Isomerism of Seleno-, Thio-, and Formic Acids and Their Dimers: Chemical Kinetics under Interstellar Conditions + https://arxiv.org/abs/2601.16115 + arXiv:2601.16115v1 Announce Type: new +Abstract: Tunnelling reactions of molecules embedded on cryogenic noble-gas matrices are being used in fundamental studies of how reactivity + varies with the nature of the supposedly inert matrix as well as pointers to the chemistry occurring in the interstellar medium + on ice-grains. To these ends we present chemical kinetic rate constants for the \textit{cis} to \textit{trans} isomerisation of + seleno-, thio- and monomeric formic acids and that of their three dimeric species, based on multidimensional calculations in the + gas-phase, from 10~K to 300~K as a guide to the matrix reactions. + oai:arXiv.org:2601.16115v1 + astro-ph.GA + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Wenhao Gao, Zhenjie Liu, Zhongxu Zhai, Jeremy L. Tinker, Jun Zhang, Arka Banerjee, Joseph DeRose, Hong Guo, Yao-Yuan Mao, Kate Storey-Fisher, Risa H. Wechsler + Judith Wurmel, John M. Simmie - BE Lyncis: An Extremely Eccentric Binary with the Nearest Known Black Hole - https://arxiv.org/abs/2601.12999 - arXiv:2601.12999v1 Announce Type: new -Abstract: We report the discovery of an exceptionally eccentric binary system, BE Lyncis (BE Lyn), which hosts the nearest known black hole (BH) to Earth. Through the analysis of $\textit{TESS}$ photometry combined with an extensive set of times of maximum light spanning 39 years, we identify BE Lyn as a high-amplitude $\delta$ Scuti star in a binary with an orbital period of $\approx15.9$ years and an extraordinary orbital eccentricity of $e=0.9989^{+0.0008}_{-0.0021}$ ($>0.9968$ at 95% confidence) -- the highest reliably measured for any binary system. Dynamical constraints impose an upper limit on the orbital inclination of $i \lesssim 4.0^{\circ}$, corresponding to a companion mass of $M_2 \gtrsim 17.5~M_{\odot}$, which unequivocally favors a black hole. This system provides a unique laboratory for studying asteroseismology in strong gravitational fields, the formation of black holes via asymmetric supernovae, and the evolution of extreme binary systems. Our work demonstrates, for the first time, the successful application of the light-travel time effect in a pulsating variable to unveil a dormant black hole, establishing a novel method for BH detection in non-interacting binaries. - oai:arXiv.org:2601.12999v1 - astro-ph.SR + Magnetar fraction in Core-Collapse Supernovae + https://arxiv.org/abs/2601.16159 + arXiv:2601.16159v1 Announce Type: new +Abstract: Magnetars are extreme neutron stars powered by ultra-strong magnetic fields ($\sim10^{14}$ Gauss) and are compelling engines for some of the most powerful extragalactic transients such as Super Luminous Supernovae, Gamma-Ray Bursts, and Fast Radio Bursts. Yet their formation rate relative to ordinary neutron stars remains uncertain, often precluding direct comparisons with the rates of these extragalactic transients. Furthermore, magnetars have been recently shown to be evolutionarily related to other neutron star classes, complicating the estimate of the exact magnetar fraction within the neutron star population. We study the magnetar birth fraction in core-collapse supernovae using pulsar population synthesis of all isolated neutron star classes in our Galaxy, incorporating self-consistently the Galactic dynamical evolution, spin-down and magneto-thermal evolution. This approach allows us to derive strong constraints from small close-to-complete observational samples. In particular, looking at the age-limited young ($<$2 kyr) neutron star population in the Milky Way we find 24 detected young neutron stars, with only 10 of them (41%) being classical rotational powered pulsars, while the others (59%) are either magnetars or central compact objects, the latter believed to be equally magnetically powered. We further compare the results with the nearby volume-limited class ($<$500 pc) of X-ray Dim Isolated Neutron stars, old nearby magnetars. We conclude that the observed population of isolated neutron stars in the Galaxy can be reproduced only by assuming a core-collapse supernova rate larger than two, and a larger magnetar fraction than previously inferred. By assuming a bimodal initial magnetic field ($B_0$) distribution at birth, we find that the magnetar class peaks between $B_0\sim 1-2.5\times10^{14}$ Gauss and represents on average $\sim50$% of the entire neutron star population. + oai:arXiv.org:2601.16159v1 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Jia-Shu Niu, Ying Zhang, Hui-Fang Xue + Celsa Pardo-Araujo, Nanda Rea, Michele Ronchi, Vanessa Graber - Continuous-Time Modelling of Black Hole Binary Evolution with Neural ODEs - https://arxiv.org/abs/2601.13019 - arXiv:2601.13019v1 Announce Type: new -Abstract: Pulsar timing arrays (PTAs) can detect the low-frequency stochastic gravitational-wave background (GWB) generated by an ensemble of supermassive black hole binaries (BHBs). Accurate determination of BHB merger timescales is essential for interpreting GWBs and constraining key astrophysical quantities such as black hole (BH) occupation fractions and galaxy coalescence rates. High-accuracy $N$-body codes such as \texttt{Griffin} can resolve sub-pc BHB dynamics but are too costly to explore a wide range of initial conditions, motivating the need for surrogate models that emulate their long-term evolution at much lower computational cost. We investigate neural ordinary differential equations (NODEs) as surrogates for the secular orbital evolution of BHBs. Our primary contribution is a parameterised NODE (PNODE) trained on an ensemble of $N$-body simulations of galaxy mergers spanning a two-dimensional parameter space defined by the initial orbital eccentricity and particle resolution $(e_i, N)$, with the learned vector field explicitly conditioned on these parameters. A single PNODE thereby learns a simulation-parameter-conditioned dynamical model for the coupled evolution of the BH pair's orbital state across the ensemble, yielding smooth trajectories from which stable hardening and eccentricity growth rates can be extracted. The PNODE accurately reproduces the secular evolution of the specific orbital energy and angular momentum, and the corresponding Keplerian orbital elements, for held-out trajectories, with modest generalisation to a partially unseen high-resolution case. Combining PNODE predictions with semi-analytical prescriptions for stellar hardening and gravitational-wave emission yields BHB merger timescales consistent with those obtained from direct $N$-body inputs within current theoretical uncertainties. - oai:arXiv.org:2601.13019v1 - astro-ph.GA - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Reanalyzing DESI DR1: 4. Percent-Level Cosmological Constraints from Combined Probes and Robust Evidence for the Normal Neutrino Mass Hierarchy + https://arxiv.org/abs/2601.16165 + arXiv:2601.16165v1 Announce Type: new +Abstract: We present cosmological parameters measurements from the full combination of DESI DR1 galaxy clustering data described with large-scale structure effective field theory. By incorporating additional datasets (photometric galaxies and CMB lensing cross-correlations) and extending the bispectrum likelihood to smaller scales using a consistent one-loop theory computation, we achieve substantial gains in constraining power relative to previous analyses. Combining with the latest DESI baryon acoustic oscillation data and using cosmic microwave background (CMB) priors on the power spectrum tilt and baryon density, we obtain tight constraints on the $\Lambda$CDM model, finding the Hubble constant $H_0=69.08\pm 0.37~\mathrm{km}\,\mathrm{s}^{-1}\mathrm{Mpc}^{-1}$, the matter density fraction $\Omega_m=0.2973\pm 0.0050$, and the mass fluctuation amplitude $\sigma_8 = 0.815\pm 0.016$ (or the lensing parameter $S_8\equiv\sigma_8\sqrt{\Omega_m/0.3}=0.811\pm 0.016$), corresponding to $0.6\%$, $1.7\%$, and $2\%$ precision respectively. Adding the Pantheon+ supernova sample (SNe), we find a preference of $2.6\sigma$ for the $w_0w_a$ dynamical dark energy model from low-redshift data alone, which increases to $2.8\sigma$ when exchanging the SNe with Planck CMB data. Combining full-shape data with BAO, CMB, and SNe likelihoods, we improve the dark energy figure-of-merit by $18\%$ and bound the sum of the neutrino masses to $M_\nu<0.057$ eV in $\Lambda$CDM and $M_\nu<0.095$ eV in the $w_0w_a$ dynamical dark energy model (both at 95\% CL). This represents an improvement of $25\%$ over the background expansion constraints and the strongest bound on neutrino masses in $w_0w_a$CDM to date. Our results suggest that the preference for the normal ordering of neutrino mass states holds regardless of the cosmological background model, and is robust in light of tensions between cosmological datasets. + oai:arXiv.org:2601.16165v1 + astro-ph.CO + hep-ex + hep-ph + hep-th + Fri, 23 Jan 2026 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Julian Chan, Alessia Gualandris, Payel Das + http://creativecommons.org/licenses/by/4.0/ + Mikhail M. Ivanov, James M. Sullivan, Shi-Fan Chen, Anton Chudaykin, Mark Maus, Oliver H. E. Philcox - Tracing cosmic structure with neutral hydrogen after the Epoch of Reionization - https://arxiv.org/abs/2601.13023 - arXiv:2601.13023v1 Announce Type: new -Abstract: We present a study of the transition of Neutral Hydrogen (HI) gas from the end of the Epoch of Reionization (EoR) to late-time large-scale structure. We examine the signature of the transition as traced through the redshifted 21-cm line with SKA-Low at $3 < z < 7$. To do so, we use the semi-numerical simulation \textsc{21cmFAST} to model the HI during the EoR and add a HI-halo based post-processing model of the late-time HI. This approach gives a robust estimate of the amplitude of the HI temperature field and predicts the observable power spectrum during the transition period. We find that our simulation pipeline reproduces the expected power spectrum trends from existing observations and theory, in addition to replicating current observational constraints on $\Omega_{\text{HI}}$. Our simulations predict a drop in power of four orders of magnitude between $4 < z < 7$. Assuming an inhomogeneous recombination model, we find a flattening of the power due to lingering neutral islands masking the late-time HI signal for $5 < z< 6.5$. Using SKA-Low deep survey parameters, we find HI power spectrum detectability at scales $k \leq 1$ $h$ Mpc$^{-1}$ for redshifts $3< z < 7$, even when using the horizon limit to mitigate foregrounds. Our results suggest a sufficient SNR of the HI power spectrum tracing the underlying halos $z < 5$, which can be used for late-time cosmology. Our results suggest that the resulting $\Omega_{\rm HI}$ constraints can trace different reionization scenarios such as a decreased escape fraction. This study implies that deep SKA-Low observations for $3< z< 7$ will be an important probe to constrain reionization parameters as well as cosmological models. - oai:arXiv.org:2601.13023v1 + The FarView Low Frequency Radio Array on the Moon's Far Side: Science and Array Architecture + https://arxiv.org/abs/2601.16170 + arXiv:2601.16170v1 Announce Type: new +Abstract: FarView is a proposed low frequency radio interferometer for deployment on the lunar far side, enabled by the Moon's radio quiet environment. Operating over 1-50 MHz inaccessible from Earth, FarView will open a new observational window and promote discovery class science in cosmology, heliophysics, Galactic and exoplanet astrophysics. The primary science is measurement of the redshifted 21 cm signal from the Cosmic Dark Ages (z=30-100), identified by the Astro2020 Decadal Survey as a priority cosmology discovery area. FarView will deliver 3D tomographic measurements and precision power spectra of neutral hydrogen in a largely linear regime, enabling tests of inflationary initial conditions, primordial non Gaussianity, dark matter properties, neutrino masses, and early dark energy. The reference design consists of 100000 crossed dipole antennas in a dense core-halo configuration spanning 200 sq km. A compact 4 km core with 83000 dipoles maximizes sensitivity to large scale cosmological modes, while 20000 halo elements extending to 14 km provide angular resolution and calibration for foreground characterization. Sensitivity forecasts indicate a 10-sigma detection of the Dark Ages 21 cm power spectrum at z=30 over five years of half duty cycle lunar night observations. An FFT-based EPIC beamformer is identified as an efficient signal processing architecture. Beyond cosmology, FarView will enable interferometric imaging of low frequency solar radio bursts, advancing space weather studies. Additional capabilities include stellar space weather observations, Galactic cosmic ray tomography via free-free absorption, and searches for auroral radio emission from exoplanet magnetospheres, a probe of exoplanet habitability. FarView represents a flagship class opportunity to establish the Moon as a platform for foundational astrophysics while delivering unique observational capabilities. + oai:arXiv.org:2601.16170v1 + astro-ph.IM astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Jamie Incley, Laura Wolz + Jack O. Burns, Judd Bowman, Tzu-Ching Chang, Gregg Hallinan, Alex Hegedus, Nivedita Mahesh, Bang Nhan, Jonathan Pober, Ronald Polidan, Willow Smith, Nithyanandan Thyagarajan - The long-term evolution of Ultra Faint Dwarf Galaxies and observational implications - https://arxiv.org/abs/2601.13049 - arXiv:2601.13049v1 Announce Type: new -Abstract: Context. In the Local Group, dwarf spheroidal galaxies (dSphs) and ultra-faint dwarf galaxies (UFDs) exhibit large velocity dispersions. These values are generally attributed to the presence of substantial amounts of dark matter (DM), in line with the predictions of the standard model of galaxy formation. However, alternative, more conservative explanations exist, such as non-virialized dynamical states induced by tidal interactions, the presence of stellar streams, and artificial inflation of the velocity dispersion caused by binary-star orbital motion. Aims. We study the dynamical evolution of UFDs using purely stellar ("dry") dynamics, without invoking DM. We dynamically evolve our systems up to a Hubble time and compare our results with observational studies and previous theoretical work. Methods. We employ direct high precision NBODY simulations performed with the NBODY6++GPU code. We explore the role of binaries in inflating the velocity dispersion of low-mass host galaxies. We also present both the stellar and dynamical evolution of the stellar population, which is necessary to properly interpret our results. Results. We find that, in all our models, the UFD remains globally quasi-stationary for approximately 3000 Myr. Subsequently, the system undergoes mass segregation and experiences a phase resembling core collapse. Red giants and white dwarfs (WD) are found to play significant, but distinct, roles. Red giants provide the dominant contribution to the luminosity, whereas WDs constitute the largest fraction of the non-luminous component, accounting for approximately 13% of the total stellar population. Finally, if not taken into account properly, velocity dispersion measurements can be strongly biased by the presence of a significant binary population, which can lead to substantial overestimates of velocity dispersion in UFDs - oai:arXiv.org:2601.13049v1 + A general spectral solver for the axisymmetric Jeans equations: fast galaxy modelling with arbitrary anisotropy + https://arxiv.org/abs/2601.16179 + arXiv:2601.16179v1 Announce Type: new +Abstract: Dynamical modelling is a fundamental tool for measuring galaxy masses and density profiles in the era of large integral-field spectroscopic surveys and Bayesian inference. Solutions based on the Jeans equations are popular due to their robustness and computational efficiency. However, traditional semi-analytic Jeans solvers often require restrictive assumptions about the velocity anisotropy to remain computationally tractable. This paper presents a new spectral solver for the axisymmetric Jeans equations designed to overcome these limitations. I first illustrate, using orbit integrations in realistic potentials, that spherical alignment of the velocity ellipsoid is a physically well-motivated approximation for galaxy modelling. The new method employs a spectral technique to solve the Jeans partial differential equations directly. Two design choices are critical for accuracy and speed: (i) solving for the slowly-varying velocity dispersion rather than the rapidly varying pressure, and (ii) imposing a Robin boundary condition to enforce the asymptotic decay on a finite domain. This formulation supports arbitrary anisotropy distributions beta(r, theta) while simultaneously increasing computational speed by orders of magnitude compared to standard high-accuracy quadratures. Validated against exact analytic benchmarks, the solver recovers intrinsic moments with sub-percent accuracy. The implementation will be included in the public JamPy package and is structured to be optimally suited for massive parallelization on specialized hardware such as GPUs, enabling the rigorous exploration of complex parameter spaces. + oai:arXiv.org:2601.16179v1 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Francesco Flammini Dotti, Roberto Capuzzo-Dolcetta, Giovanni Carraro, Alessandro Alberto Trani, Rainer Spurzem + Michele Cappellari (University of Oxford) - Was the Early Universe Quantum? Falsifying Classical Stochastic Inflation - https://arxiv.org/abs/2601.13053 - arXiv:2601.13053v1 Announce Type: new -Abstract: Inflationary cosmology successfully accounts for the observed properties of primordial fluctuations using quantum field theory in an expanding background. However, the quantum nature of these fluctuations has not been experimentally established, since classical stochastic models could reproduce the observed two-point statistics by construction. Existing approaches to testing primordial quantumness focus primarily on Bell inequalities, which provide a sharp conceptual criterion but are difficult to implement with cosmological observables. In this work we adopt a falsification-based approach. We define a precise classical hypothesis for the origin of primordial perturbations (local stochastic fields admitting a positive probability distribution) and identify inequality constraints that must be satisfied within this class. We show how violations of these classicality inequalities can be probed using realistic cosmological observables, without invoking Bell tests or non-commuting measurement settings. We further identify symmetry-protected spectator sectors in which quantum coherence is parametrically preserved during inflation, allowing violations of observable magnitude to survive decoherence. Our results show that large-scale structure and future 21 cm surveys provide a viable and quantitative route to falsifying classical stochastic descriptions of primordial fluctuations. - oai:arXiv.org:2601.13053v1 - astro-ph.CO - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Veronica Sanz - - - Simulating the quasi-ballistic regime of a short Gamma-Ray Burst jet - https://arxiv.org/abs/2601.13056 - arXiv:2601.13056v1 Announce Type: new -Abstract: This study extends the 3D magnetohydrodynamic (MHD) simulation of a jet emerging from a binary neutron star (BNS) merger presented in Pavan et al. (2023), in which an incipient jet was manually injected into the realistic environment imported from a previous general-relativistic MHD simulation of a merging BNS system. The jet evolution is followed up to almost 10 seconds without loss of resolution. Our results reveal that the jet faces challenges in penetrating the dense surroundings, leading to a barely successful outflow that exhibits structural asymmetries and low Lorentz factors. By the end of the extended simulation, 98% of the jet energy is converted to kinetic form and its angular structure is stabilized. The physical quantities inferred thus provide reliable inputs for afterglow emission calculations. This work demonstrates a method for simulating jets in 3D up to nearly ballistic regimes that is general and ready to be applied to any jet in a BNS merger context. - oai:arXiv.org:2601.13056v1 + Evolution of the recent high-accretion state of the recurrent nova T CrB: HST, Swift, NuSTAR, and XMM-Newton observations + https://arxiv.org/abs/2601.16190 + arXiv:2601.16190v1 Announce Type: new +Abstract: As the recurrent nova T Coronae Borealis (T CrB) approaches its next predicted thermonuclear eruption, it is currently exhibiting a "super-active state" (SAS) characterized by enhanced multiwavelength emission similar to the behavior recorded prior to the 1946 outburst. We present a multiwavelength analysis of the SAS and the subsequent "faint state" using observations from HST, Swift, NuSTAR, and XMM-Newton. Our results indicate that the SAS was driven by an increase in the mass accretion rate, which caused the accretion disk's boundary layer to become optically thick. A weighted least squares regression analysis quantifies the evolution of the accretion components, displaying a highly significant (4.5$\sigma$) increase in the luminosity of the optically thin cooling flow (L$_{cf}$) and a marginal (2.58$\sigma$) decrease in the optically thick boundary layer luminosity (L$_{bb}$) as the system transitioned into the faint state. We find that this dimming is consistent with an intrinsic change in the accretion flow rather than dust obscuration, supported by the lack of infrared excess and the stability of the 2175 \AA\ feature. Additionally, a time-series analysis using autoregressive modeling to account for correlated red noise revealed no significant periodicities, thereby disputing the previously reported $\sim$6000 s signal. These findings suggest that the pre-outburst evolution of T CrB is characterized by significant changes in the accretion disk structure and boundary layer, providing a self-consistent physical framework for the system's behavior as it approaches eruption. + oai:arXiv.org:2601.16190v1 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Emma Dreas, Andrea Pavan, Riccardo Ciolfi, Annalisa Celotti + G. J. M. Luna, N. P. M. Kuin, K. Mukai, J. L. Sokoloski, K. Page, J. P. Osborne - Antarctic Infrared Binocular Telescope: Early Data Release of observations in the 1.4 {\mu}m water-vapor-absorption band - https://arxiv.org/abs/2601.13068 - arXiv:2601.13068v1 Announce Type: new -Abstract: Ground-based observations around 1.4 $\mu$m are normally limited by strong absorption of telluric water-vapor. However, Dome A, Antarctica has exceptionally dry conditions that offer a unique opportunity for observations in this band. We designed a new filter covering 1.34--1.48 $\mu$m, namely $W'$, and installed it on the Antarctic Infrared Binocular Telescope (AIRBT) at Dome A in 2025. AIRBT comprises two identical 15 cm optical tube assemblies and two InGaAs cameras equipped with $J$ and $W'$ filters, respectively. With this Early Data Release (EDR), we aim to evaluate the performance of the $W'$ band at Dome A to observe objects with water-vapor features. This EDR covers $\thicksim 20 \ \mathrm{deg^2}$ in the Galactic plane using $\thicksim 20,000$ images in three nights. For 2 s exposures, the 5 $\sigma$ limiting magnitude histogram peaks at $J \thicksim 11.5$ mag (Vega) and $W' \thicksim 9.9$ mag, respectively. The $J-W'$ vs $J-H$ color-color diagram distinguishes ultracool candidates with water-vapor-absorption features from reddened early type stars. Furthermore, later-type stars tend to exhibit stronger water-vapor absorption. Some sources show larger $\Delta W'$ than $\Delta J$ across the three nights, which we attribute to variations of their water-vapor-absorption depth. We conclude that it will be efficient to search for ultracool stars and estimate their spectral subtypes using $W'$ band imaging at Dome A, where the atmospheric transmission is high and stable. - oai:arXiv.org:2601.13068v1 - astro-ph.IM + On the Missing Red Giants near the Galactic Center + https://arxiv.org/abs/2601.16191 + arXiv:2601.16191v1 Announce Type: new +Abstract: There is a long-acknowledged deficiency of bright red giants relative to fainter old stars within a few arc seconds of Sgr A*. We explore whether this could be due to tidal stripping by the central black hole. This requires putting the stars onto highly eccentric orbits, for which we evaluate diffusion by both scalar resonant and non-resonant relaxation of the orbital angular momentum. We conclude that tidal stripping does not discriminate sufficiently between main-sequence and red giant stars. While the tidal loss cone increases with stellar radius, the rate of diffusion into the loss cone increases only logarithmically, whereas the lifetime on the red giant branch decreases more rapidly than $R_*^{-1}$. In agreement with previous studies, we find that stellar collisions are a more likely explanation for the deficiency of bright red giants relative to fainter ones. + oai:arXiv.org:2601.16191v1 astro-ph.GA astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Pu Lin, Haonan Yang, Bin Ma, Jinji Li, Haoran Zhang, Michael C. B. Ashley, Zhong-Nan Dong, Lu Feng, Wei Huang, Yi Hu, Zhaohui Shang, Yun Shi, Shijie Sun, Xu Yang, Yong Zhang + Taeho Kim, Jeremy Goodman - BOWIE-ALIGN: Sub-solar C/O ratio and metallicity atmosphere of the misaligned hot Jupiter HAT-P-30b - https://arxiv.org/abs/2601.13104 - arXiv:2601.13104v1 Announce Type: new -Abstract: We present the JWST NIRSpec/G395H transmission spectrum of the misaligned hot Jupiter HAT-P-30b from 2.8--5.2 $\mu$m as part of the BOWIE-ALIGN survey, a comparative survey designed to probe the link between planet formation and atmospheric composition in samples of misaligned and aligned hot Jupiters orbiting F-type stars. Through independent data reductions and retrieval analyses, we find evidence for absorption features of H$_2$O and CO$_2$ in the atmosphere of HAT-P-30b. Our retrieved abundances are consistent with equilibrium chemistry, from which we infer a sub-solar C/O ratio (0.16--0.45), and sub-solar and sub-stellar metallicity (0.2--0.8$\times$solar, compared to a stellar metallicity of 1.1--1.6$\times$solar), with muted spectral features. This composition challenges formation models of continuous migration and accretion within a steady disc of stellar metallicity, and could be the result of low C/O ratio gas accretion within the water ice line, low metallicity accretion due to the trapping of volatiles further out in the disc, or the combined accretion of low metallicity gas and carbon-poor solids. - oai:arXiv.org:2601.13104v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alastair B. Claringbold, Chloe E. Fisher, James Kirk, Eva-Maria Ahrer, Anna B. T. Penzlin, Daniel P. Thorngren, Mercedes L\'opez-Morales, Peter J. Wheatley, Lili Alderson, Richard A. Booth, Duncan A. Christie, Charlotte Fairman, Nathan J. Mayne, Mason McCormack, Annabella Meech, James E. Owen, Vatsal Panwar, Denis E. Sergeev, Daniel Valentine, Hannah R. Wakeford, Maria Zamyatina - - - Tidal capture and repeating partial tidal disruption events of giant stars - https://arxiv.org/abs/2601.13113 - arXiv:2601.13113v1 Announce Type: new -Abstract: When an object is scattered near a supermassive black hole (SMBH), tidal oscillations excited within it reduce its orbital energy, leading to capture by the SMBH. This process, called tidal capture, can also occur when the object approaches even closer to the SMBH, resulting in a partial tidal disruption event (pTDE). Previous studies on pTDEs of main-sequence stars have shown that as the disruption intensifies, dynamical effects dominate over tidal oscillations, causing the remnant material to acquire a kick velocity instead of being captured by the SMBH. In this work, we performed hydrodynamic numerical simulations of pTDEs involving giant stars. We found that for weaker disruptions, the dynamical behavior of the remnant material resembles that of main-sequence stars. However, as the disruptions deepen, the remnant material transitions from gaining energy to losing energy, leading to capture by the SMBH. This behavior markedly differs from that of main-sequence stars, demonstrating that the presence of a compact core significantly influences the dynamical processes in pTDEs. Our simulations reveal that the energy change of the remnant material strongly correlates with asymmetric mass -- lossspecifically, the difference in mass outflow between the Lagrange points L1 and L2. This suggests that the energy change stems from asymmetric mass loss, consistent with conclusions from previous studies on main-sequence stars. However, quantitative analysis contradicts earlier models, indicating that the dynamical model of pTDEs requires further refinement. Finally, we discuss the characteristics of repeating pTDEs produced by this process and their potential observability, as well as the implications for the long-term orbital evolution of high eccentricity extreme mass ratio inspiral systems. - oai:arXiv.org:2601.13113v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Di Wang, Fa-Yin Wang - - - Simulating radio emission from flickering AGN jets: travelling shocks and hotspot brightening - https://arxiv.org/abs/2601.13138 - arXiv:2601.13138v1 Announce Type: new -Abstract: We investigate the impact of flickering variability in jet power on the luminosity and morphology of radio galaxies. We use a Lagrangian particle method together with relativistic hydrodynamics simulations using the PLUTO code to track the evolution of electron spectra through particle acceleration at shocks and cooling processes. We introduce an adapted version of this method which improves tracking of adiabatic cooling in regimes where low density jet material mixes with high density from the ambient medium in the lobes. We find that rapid increases in jet power can lead to large increases in hotspot luminosity due to the interaction of a travelling shock structure with the pre-existing shock structure at the jet head. We show that in some cases it may be possible to identify a bright region of emission corresponding to a shock travelling along the jet axis. We find that the time-averaged radiative efficiency of variable jets is similar to their steady counterparts, but find significant departures from this on an instantaneous basis. We suggest that, together with environmental effects and differences in the average powers of jets, variable jet powers may have a significant impact on how we understand the diversity of radio jets seen in observations and have significant implications for interpretations of jet powers, energy budgets and luminosity-linear size diagrams. - oai:arXiv.org:2601.13138v1 - astro-ph.HE - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Emma L. Elley, James H. Matthews, Dipanjan Mukherjee, Bhargav Vaidya - - - MARVEL Analysis of the Measured High-resolution Spectra of CO Isotopologues - https://arxiv.org/abs/2601.13141 - arXiv:2601.13141v1 Announce Type: new -Abstract: Carbon monoxide is thought to be the second most abundant molecule in the Universe. This makes observation of both its parent isotopologue ($^{12}$C$^{16}$O) and its stable isotopologues, $^{13}$C$^{16}$O, $^{12}$C$^{18}$O, $^{12}$C$^{17}$O, $^{13}$C$^{18}$O and $^{13}$C$^{17}$O, important in variety of objects. Here the MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm is used to determine precise rotational vibrational energy levels for the five minor isotopologues of carbon monoxide in their electronic ground state. A review of 27 literature sources yields 3716, 1454, 89, 728 and 57 validated transitions for $^{13}$C$^{16}$O, $^{12}$C$^{18}$O, $^{12}$C$^{17}$O, $^{13}$C$^{18}$O and $^{13}$C$^{17}$O, respectively, giving 863, 499, 33, 345 and 45 empirically determined, rotation vibration energy levels, respectively. - oai:arXiv.org:2601.13141v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Timur Grigorev, Yuhang Dai, Max Potter, Xiaoyu Xiang, Keyu Zhang, Jonathan Tennyson - - - Forecasting Continuum Intensity for Solar Active Region Emergence Prediction using Transformers - https://arxiv.org/abs/2601.13144 - arXiv:2601.13144v1 Announce Type: new -Abstract: Early and accurate prediction of solar active region (AR) emergence is crucial for space weather forecasting. Building on established Long Short-Term Memory (LSTM) based approaches for forecasting the continuum intensity decrease associated with AR emergence, this work expands the modeling with new architectures and targets. We investigate a sliding-window Transformer architecture to forecast continuum intensity evolution up to 12 hours ahead using data from 46 ARs observed by SDO/HMI. We conduct a systematic ablation study to evaluate two key components: (1) the inclusion of a temporal 1D convolutional (Conv1D) front-end and (2) a novel `Early Detection' architecture featuring attention biases and a timing-aware loss function. Our best-performing model, combining the Early Detection architecture without the Conv1D layer, achieved a Root Mean Square Error (RMSE) of 0.1189 (representing a 10.6% improvement over the LSTM baseline) and an average advance warning time of 4.73 hours (timing difference of -4.73h), even under a stricter emergence criterion than previous studies. While the Transformer demonstrates superior aggregate timing and accuracy, we note that this high-sensitivity detection comes with increased variance compared to smoother baseline models. However, this volatility is a necessary trade-off for operational warning systems: the model's ability to detect micro-changes in precursor signals enables significantly earlier detection, outweighing the cost of increased noise. Our results demonstrate that Transformer architectures modified with early detection biases, when used without temporal smoothing layers, provide a high-sensitivity alternative for forecasting AR emergence that prioritizes advance warning over statistical smoothness. - oai:arXiv.org:2601.13144v1 - astro-ph.SR - cs.LG - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Jonas Tirona, Sarang Patil, Spiridon Kasapis, Eren Dogan, John Stefan, Irina N. Kitiashvili, Alexander G. Kosovichev, Mengjia Xu - - - SolARED: Solar Active Region Emergence Dataset for Machine Learning Aided Predictions - https://arxiv.org/abs/2601.13145 - arXiv:2601.13145v1 Announce Type: new -Abstract: The development of accurate forecasts of solar eruptive activity has become increasingly important for preventing potential impacts on space technologies and exploration. Therefore, it is crucial to detect Active Regions (ARs) before they start forming on the solar surface. This will enable the development of early-warning capabilities for upcoming space weather disturbances. For this reason, we prepared the Solar Active Region Emergence Dataset (SolARED). The dataset is derived from full-disk maps of the Doppler velocity, magnetic field, and continuum intensity, obtained by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). SolARED includes time series of remapped, tracked, and binned data that characterize the evolution of acoustic power of solar oscillations, unsigned magnetic flux, and continuum intensity for 50 large ARs before, during, and after their emergence on the solar surface, as well as surrounding areas observed on the solar disc between 2010 and 2023. The resulting ML-ready SolARED dataset is designed to support enhancements of predictive capabilities, enabling the development of operational forecasts for the emergence of active regions. The SolARED dataset is available at https://sun.njit.edu/sarportal/, through an interactive visualization web application. - oai:arXiv.org:2601.13145v1 - astro-ph.SR - cs.LG - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Spiridon Kasapis, Eren Dogan, Irina N. Kitiashvili, Alexander G. Kosovichev, John T. Stefan, Jake D. Butler, Jonas Tirona, Sarang Patil, Mengjia Xu - - - Time variations of the mean magnetic flux in active regions of different magneto-morphological classes - https://arxiv.org/abs/2601.13168 - arXiv:2601.13168v1 Announce Type: new -Abstract: Using a recently suggested magneto-morphological classification (MMC, Abramenko, 2021, MNRAS Vol 507) of solar active regions (ARs), we explored 3048 ARs, observed from12 May 1996 to 27 December 2021. Magnetograms were acquired with the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) and with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). - ARs were separated between three classes: class A - regular ARs (bipoles which follow the empirical rules compatible with the mean field dynamo theory); class B - irregular ARs (``wrong'' bipoles and multipolars); class U - unipolar sunspots. An aim of the present study is to explore time variations of a typical unsigned magnetic flux of ARs of different classes. The typical flux was acquired as the mean flux over all ARs of a given class observed during one solar rotation. The time profiles of the mean fluxes for different classes were compared. - We found that, except for periods of deep solar minima, the mean flux of B-class ARs always dominate that of A-class ARs, and, what is the most important, the time profile of B-class ARs is highly intermittent versus the rather smooth and quazi-constant A-class profile. Intermittency implies a direct involvement of turbulence. - We conclude that, through the entire active phase, the Sun is capable of producing regular moderate ARs at a quazi-constant rate along with the production of large and complex irregular ARs in the very intermittent manner. The result is the first observational evidence for the long-standing speculative assumption on the involvement of the convection zone turbulence into the regular global dynamo-process on a stage of the active regions formation. - oai:arXiv.org:2601.13168v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1007/s11207-026-02607-3 - Anastasiya Zhukova, Valentina Abramenko - - - Toward Reliable Interpretations of Small Exoplanet Compositions: Comparisons and Considerations of Equations of State and Materials Used in Common Rocky Planet Models - https://arxiv.org/abs/2601.13176 - arXiv:2601.13176v1 Announce Type: new -Abstract: The bulk compositions of small planets ($R_p< 2 \mathrm{R}_\oplus$) are directly linked to their formation histories, making reliable compositional constraints imperative for testing models of planet formation and evolution. Because exoplanet interiors cannot be directly observed, their make-up must be inferred from mass-radius-composition models that link assumed stellar abundances to the direct observables: planetary mass and radius. There are a variety of such models in the literature, each adopting different equations of state (EOS) to describe the materials' properties at depth and varying assumptions about the minerals present within the planets. These EOS+mineral suites provide the foundations for compositional inferences, but they have not yet been systematically compared. In this work, we review several suites, with a detailed description of the basic structure, mineral physics, and materials within standard small planet models. We show that EOS+mineral suites predict planet densities whose differences are comparable to current observational uncertainties, which present a challenge for robustly interpreting and classifying small planets. We apply a powerful small-planet characterization framework, which illustrates that variations among EOS+mineral suites lead to inconsistent conclusions for both individual planets and sample-level demographics. Our results demonstrate the need for more careful considerations of the materials and EOS used in mass-radius-composition models, especially given the current focus on finding and characterizing potentially habitable rocky planets. We conclude with recommendations for best practices so that future interpretations of small planets and their formation are accurate and consistent. - oai:arXiv.org:2601.13176v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Joseph Schulze, Natalie Hinkel, Wendy Panero, Cayman Unterborn - - - Broadband Variability Analysis of FSRQ PKS\,0402-362 with Indications of Quasi-Periodic Modulation - https://arxiv.org/abs/2601.13181 - arXiv:2601.13181v1 Announce Type: new -Abstract: We present a comprehensive temporal and spectral study of the flat-spectrum radio quasar PKS~0402$-$362 using \textit{Fermi}-LAT/Swift-XRT/UVOT observations spanning from MJD 54686-60321. The $\gamma$-ray light curve exhibits multiple phases of enhanced activity, with the fractional variability parameter ($F_{\mathrm{var}}$) showing larger amplitudes at longer timescales, consistent with variability trends observed in other FSRQs. Statistical analysis of the flux and spectral index distributions using the Anderson--Darling test and histogram fitting reveals that both distributions deviate from a single log-normal form and are better represented by a double log-normal profile, indicating two distinct flux states. A search for quasi-periodic oscillations in the $\gamma$-ray emission using the Lomb--Scargle periodogram identified a significant periodic signal at $\sim$413~days with a confidence level exceeding $3\sigma$. However the proximity of the timescale to one year and limited number of observed cycles prevents a definitive interpretation. Broadband spectral energy distributions for six flux states were modeled using a one-zone leptonic framework incorporating synchrotron, synchrotron self-Compton (SSC), and external Compton (EC) components. The SEDs are well reproduced with physically reasonable parameters: high-flux states exhibit harder electron spectra and lower magnetic field strengths ($B \sim 0.2--0.6\,\mathrm{G}$), while low-flux states show softer spectra and stronger magnetic fields ($B \sim 1.3\,\mathrm{G}$). The fitted break energy decreases during high-flux states, suggesting enhanced radiative cooling and a transition toward a particle- or kinetic-energy-dominated jet. These trends are consistent with the ``harder-when-brighter'' behavior commonly observed in blazars. - oai:arXiv.org:2601.13181v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zeeshan Nazir, Sikandar Akbar, Zahir Shah, Athar A. Dar, Zahoor Malik - - - Timescales diagnostics for saving viscous and MHD-driven dusty discs from external photoevaporation - https://arxiv.org/abs/2601.13200 - arXiv:2601.13200v1 Announce Type: new -Abstract: The evolution of protoplanetary discs is a function of their internal processes and of their environment. It is unclear if angular momentum is mainly removed viscously or by magnetic winds, or by a combination of the two. While external photoevaporation is expected to influence disc evolution and dispersal, there are observational limitations towards highly irradiated discs. The interplay between these ingredients and their effect on the gas and dust distributions are poorly understood. We investigate the evolution of both the gaseous and solid components of viscous, MHD-wind or hybrid discs, in combination with external FUV-driven mass loss. We test which combinations of parameters protect discs from external irradiation, allowing the solid component to live long enough to allow planet formation to succeed. We run a suite of 1D simulations of smooth discs with varying initial sizes, levels of viscous and MHD-wind stresses modeled via an $\alpha$ parametrisation, and strengths of the external FUV environment. We track disc radii, various lifetime diagnostics, and the amount of dust removed by the photoevaporative wind, as a function of the underlying parameters. The biggest role in determining the fate of discs is played by a combination of its ability to spread radially outwards and the strength of FUV-driven erosion. While MHD wind-driven discs experience less FUV erosion due to the lack of spread, they do not live for longer compared to viscously evolving discs, especially at low-to-moderate FUV fluxes, while higher fluxes yield disc lifetimes that are insensitive to the disc's angular momentum transport mechanism. For the solid component, the biggest role is played by a combination of inward drift and removal by FUV winds. This points to the importance of other physical ingredients, such as disc substructures, even in highly-irradiated disc regions, in order to retain solids. - oai:arXiv.org:2601.13200v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Gabriele Pichierri, Giovanni Rosotti, Rossella Anania, Giuseppe Lodato - - - Optomechanical design of the DragonCam microscopic camera - https://arxiv.org/abs/2601.13221 - arXiv:2601.13221v1 Announce Type: new -Abstract: The DragonCam Microscopic Camera is an instrument being developed for NASA's Dragonfly mission [1] to Saturn's moon Titan. The Microscopic Camera will be body-fixed to the Dragonfly vehicle and will image the surface at a distance of about one meter (98.6 cm nominal) with a pixel scale of better than 60 microns/pixel and a nominal 52 degree angle to the Titan surface. With the 4.8 um pixel pitch of the sensor, this is a focal length of about 77.5 mm. To accommodate range variations due to vehicle pose and surface topography, the Microscopic Camera has a focus mechanism to give it a depth of field (DOF) of about 130mm. Since the Microscopic Camera's boresight is tilted by 52{\deg} off the vertical, the optical configuration has a compensating tilted focal plane, taking advantage of the Scheimpflug imaging principle. The optics are all-refractive with nine elements, a six-element stationary group and a three-element moving group. A plano-plano window seals the optics from the environment and also serves as the substrate for a bandpass filter. The optomechanical system is derived from the Mars Hand Lens Imager [11]; the moving group is mounted to a linear slide which is translated via a cam follower by the rotation of a cam driven by a stepper motor. The Microscopic Camera is designed to survive at temperatures as low as -130C without power. The camera is enclosed in a cavity in the foam insulation covering the spacecraft and looking through a single-pane window. Prior to imaging, the camera will be heated to operating temperature (nominal -30C) for proper actuation of the mechanism. STOP analysis has been performed to demonstrate that optical performance is maintained after heating. Software focus merging will be performed in the onboard camera control electronics to minimize image data downlink requirements. - oai:arXiv.org:2601.13221v1 - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1117/12.3065774 - Proceedings of the SPIE, Volume 13599, id. 135990B 16 pp. (2025) - M. J. Clark, M. A. Ravine, M. A. Caplinger, B. A. Lindenfeld, J. D. Laramee, R. S. Bronson, A. D. Giglio, B. G. Crowther - - - An efficient model of cosmology dependence in the covariance matrix of the matter power spectrum - https://arxiv.org/abs/2601.13245 - arXiv:2601.13245v1 Announce Type: new -Abstract: Covariance matrices are essential cosmological probes of fundamental physics, providing information on numerous fundamental physical parameters and varying with any change in the underlying cosmology. However, this cosmology dependence, while providing excellent information, also makes them computationally intensive to compute, as a new covariance matrix must explicitly be calculated for every variation in cosmology before comparisons to observational data can be made. In this paper, we develop an efficient model for estimating the parameter dependence of the covariance matrix of the matter power spectrum by Taylor expanding around a known value of the parameter space. This method allows us to use a relatively small number of input cosmologies, specifically one fiducial cosmology and two further cosmologies for each parameter. We explicitly calculate the covariance matrices for these cosmologies and then develop a new model that allows us to interpolate from these the form of the covariance matrix with a cosmology that is located elsewhere in that given parameter space without explicit perturbation theory calculations. This method speeds up covariance matrix calculations in new cosmologies by orders of magnitude compared to explicit perturbation theory calculations at each point in a given parameter space. Using different approximations, we develop three versions of our interpolated covariance matrix and validate the model by recreating all of our input cosmologies using all three forms, both with and without super-sample covariance corrections in each case, and show that the models provide robust recreations of the original results, with the different approximations being valid in certain regimes. - oai:arXiv.org:2601.13245v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Theodore Steele, Robert Smith, Roisin O'Connor - - - A Newly Identified Degeneracy Keeps the Planetary Interpretation Viable for OGLE-2011-BLG-0950 - https://arxiv.org/abs/2601.13276 - arXiv:2601.13276v1 Announce Type: new -Abstract: The microlensing event OGLE-2011-BLG-0950 exhibits the well-known ``Planet/Binary'' degeneracy, in which distinct lens configurations produce similar light curves but imply substantially different mass ratios between the lens components. A previous study suggested that high-resolution imaging could break this degeneracy through differences in the lens-source relative proper motion. In this work, we identify a new planetary model for this event that arises from a newly identified degeneracy, simultaneously reproducing the observed light curve and remaining consistent with the relative proper motion measured from high-resolution imaging. By combining constraints from the light-curve modeling and high-resolution observations, we infer a lens system consisting of a $\sim 1~M_{\odot}$ host star orbited by a $\sim 1.5~M_{\rm Jup}$ planet, with a projected separation of about 2 or 8 au, subject to the ``Close/Wide'' degeneracy. Our reanalysis of the color-magnitude diagram further indicates that the source star has unresolved companions that contribute non-negligible blended light, highlighting the importance of carefully accounting for source and lens companions in future Roman microlensing analyses. Finally, we show that adopting a single mass--luminosity relation significantly underestimates the uncertainties in the inferred lens properties for host masses $\gtrsim 1~M_{\odot}$. - oai:arXiv.org:2601.13276v1 - astro-ph.EP - astro-ph.GA - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jiyuan Zhang, Weicheng Zang, Andrzej Udalski, Hongjing Yang, Shude Mao, Micha{\l} K. Szyma\'nski, Igor Soszy\'nski, Radoslaw Poleski, Krzysztof Ulaczyk, Pawe{\l} Pietrukowicz, Szymon Koz{\l}owski, Jan Skowron, Przemek Mr\'oz, Sean K. Terry, Andrew Gould - - - The Occurrence Rate of Nearby Planetary Companions to Hot Jupiters - https://arxiv.org/abs/2601.13302 - arXiv:2601.13302v1 Announce Type: new -Abstract: Of the > 500 confirmed transiting hot jupiters and approximately 2000 additional candidates today, only ten are known to have nearby companion planets. The survival of nearby companions means that these hot jupiters cannot have migrated to their present location via dynamically disruptive high-eccentricity migration but instead have undergone disk migration or formed in situ. The occurrence rate for these nearby companions, therefore, constrains the relative efficiency of different hot jupiter formation pathways. Here, we perform a uniform box least-squares search for nearby transiting companions to hot jupiters in the first five years of TESS data. Accounting for observational completeness and detection efficiency, we arrive at an occurrence rate of $(7.6^{+5.5}_{-3.8})\%$, which is a lower limit on the fraction of hot jupiters that underwent disk migration or in situ formation. Comparing this rate with that derived from transit-timing variation searches suggests that hot jupiters are likely mostly aligned with their nearby companions, but their apparently higher incidence of grazing transits may point to a slight preferential misalignment. We also synthesize evidence that hot jupiters with nearby companions may have cold companions at a rate similar to that of other hot jupiters. Comprehensive transit, radial velocity, and stellar obliquity measurements in hot jupiter systems with nearby companions will be necessary to fully account for the relative prevalence of proposed hot jupiter formation pathways. - oai:arXiv.org:2601.13302v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Lizhou Sha, Andrew M. Vanderburg, Chelsea X. Huang, Samuel Christian, Nicholas Saunders, Khalid Barkaoui, Alexander Belinski, Serge Bergeron, Allyson Bieryla, Karen A. Collins, Giuseppe Conzo, Akihiko Fukui, Tristan Guillot, Kai Ikuta, David W. Latham, Jerome P. de Leon, Bob Massey, Gabriel Murawski, Felipe Murgas, Norio Narita, Mohammad Odeh, Enric Palle, Richard P. Schwarz, Gregor Srdoc, Chris Stockdale, Ian A. Waite, Francis P. Wilkin - - - Testing the Physical Parameter Constraining Power of HCN and HNC with Neural Networks - https://arxiv.org/abs/2601.13305 - arXiv:2601.13305v1 Announce Type: new -Abstract: We quantify the utility of HCN and HNC to characterize gas conditions in the nearby starburst galaxy NGC 253. We use measurements from the Atacama Large Millimeter/Submillimeter Array (ALMA) Large Program ALCHEMI: the ALMA Comprehensive High-resolution Molecular Inventory. Using different subsets of the eight total HCN and HNC transitions measured by ALCHEMI, we test the number and combinations of transitions necessary for constraining the temperature, H$_2$ volume and column densities, cosmic-ray ionization rate, and beam-filling factor in three representative regions within NGC 253. We use these combinations of HCN and HNC transitions to constrain chemical and radiative transfer models and infer the gas conditions using a Bayesian nested sampling algorithm combined with neural network models for increased efficiency. By comparing the shapes of the resulting posterior distributions, as well as the medians and uncertainties for each gas parameter, from each test case to what we obtain with the full set of eight transitions (the control), we quantify how well each test reproduces the control. We find that multiple transitions each of both molecules are required to obtain a median parameter value within a factor of 2 of the control with an uncertainty less than 2-3 times that of the control. We also find that transition combinations that feature a range of upper-state energies are most effective. We show that single transitions, such as HCN J = 1-0 or 3-2, are among the worst-performing combinations and result in parameter values up to an order of magnitude different than the control. - oai:arXiv.org:2601.13305v1 - astro-ph.GA - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3847/1538-4357/ae3567 - Erica Behrens, Jeffrey G. Mangum, Mathilde Bouvier, Cosima Eibensteiner, Serena Viti - - - Signatures of Black Hole Spin and Plasma Acceleration in Jet Polarimetry II: Off-Axis Jets - https://arxiv.org/abs/2601.13307 - arXiv:2601.13307v1 Announce Type: new -Abstract: We analyze the polarization of optically thin, stationary, axisymmetric black hole jets at scales of order the light cylinder radius. Our work generalizes the face-on results of Gelles et al. (2025) to arbitrary viewing inclination. Due to a combination of geometry and relativistic aberration, the polarization of the jet is not left-right symmetric, and the degree of asymmetry can shed light on both the viewing angle and the plasma bulk Lorentz factor. We show that there is always a radius in the jet at which the polarization transitions from azimuthal to radial; this radius is different along the spine and limb of the jet. We propose metrics that can be used to constrain the black hole spin, inclination angle, and plasma Lorentz factor from these polarimetric signatures, and we discuss the impact of limb-brightening on these measurements. We anticipate that these polarimetric signatures can be studied with current or forthcoming data in M87, NGC 315, NGC 4261, Centaurus A, Cygnus A, and other systems. Observations of the polarization of the base of the counter-jet in higher inclination sources would provide a particularly promising probe of black hole spin. - oai:arXiv.org:2601.13307v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/publicdomain/zero/1.0/ - Zachary Gelles, Andrew Chael, Eliot Quataert - - - Galaxy transformation across the cosmic web: The influence zone of filaments - https://arxiv.org/abs/2601.13309 - arXiv:2601.13309v1 Announce Type: new -Abstract: The matter distribution in the Universe exhibits a rich variety of structures forming the cosmic web. These structures arise from the anisotropic gravitational collapse of primordial density fluctuations and define the pathways along which galaxies flow from voids to high-density clusters. Local density variations within these structures play a fundamental role in driving the environmental evolution of galaxies. To characterise filament boundaries, we analysed galaxy overdensity profiles around filaments in two redshift ranges: $0.05 < z < 0.1$ and $0.1 < z < 0.3$. Perpendicular and parallel profiles were derived by averaging galaxy overdensity as a function of distance. Characteristic scales and central overdensities were then analysed by fitting analytical models, specifically exponential and power-law families. We also introduced normalised density profiles to account for survey incompleteness. The perpendicular overdensity profiles show a nearly constant value in the central regions $D_{fila} < 1$ Mpc, decreasing at distances up to $\approx 10$ Mpc. The mean physical widths (scale radii) at $0.05 < z < 0.1$ and $0.1 < z < 0.3$ are $2.39 \pm 0.69$ and $5.56 \pm 2.29$ Mpc, respectively. This scale difference between redshift ranges is also evident in the normalised profiles. Conversely, profiles along filaments remain constant at distances larger than $\approx 20$ Mpc from the nearest intersection. Our results show that the influence zone of cosmic filaments extends up to $\sim 10$ Mpc from their spines. Furthermore, a mild evolution in structural parameters is observed over the past $\sim 4$ Gyr, suggesting that filaments undergo measurable changes even at relatively low redshifts. - oai:arXiv.org:2601.13309v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - J. A. L. Aguerri, S. Zarattini - - - Variability as a new discovery channel for Intermediate-Mass Black Holes in the Time Domain Era - https://arxiv.org/abs/2601.13311 - arXiv:2601.13311v1 Announce Type: new -Abstract: Between the groundbreaking detections of stellar-mass black holes by LIGO/Virgo/KAGRA and JWST's revelation of a surprisingly abundant population of supermassive black holes, one crucial missing link remains: the elusive intermediate-mass black holes (IMBHs). IMBHs represent a key phase in the hierarchical growth of black holes, yet they have persistently evaded detection. Traditional methods, effective for both actively accreting and quiescent black holes, have largely failed to uncover this hidden population. Here, we argue that novel observational strategies--particularly time-domain variability studies of active galactic nuclei (AGN) and tidal disruption events--provide a promising path forward. Finding IMBHs will resolve critical gaps in our understanding of black hole formation and the various mechanisms driving their subsequent growth. The upcoming Vera C. Rubin Observatory, with its unprecedented capacity to monitor the dynamic sky, stands to revolutionize our ability to detect these long-sought IMBHs, shedding new light on the assembly history of black holes across cosmic time. - oai:arXiv.org:2601.13311v1 - astro-ph.HE - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1038/s41550-025-02759-5 - Colin J. Burke, Priyamvada Natarajan - - - Multi-Tracer Cross-Correlations of the Unresolved $\gamma$-Ray Sky - https://arxiv.org/abs/2601.13312 - arXiv:2601.13312v1 Announce Type: new -Abstract: Our understanding of the $\gamma$-ray sky has greatly advanced, yet studying the unresolved $\gamma$-ray background (UGRB) can unveil the nature of the faintest $\gamma$-ray source populations in the Universe. Statistical cross-correlations between the UGRB and tracers of large-scale cosmic structure allow us to infer which sources contribute the most to this emission. In this work, we examine the angular correlation between the UGRB and the matter distribution traced by galaxies, using twelve years of Fermi Large Area Telescope (LAT) observations along with three years of Dark Energy Survey (DES) data. We detect a correlation with a signal-to-noise ratio of 7.96, primarily driven by large angular scales. We then perform a multi-tracer analysis that combines this measurement with the cross-correlation between $\gamma$ rays and DES weak lensing. The two single-tracer results are mutually consistent, and their combination yields a total significance of 8.6, firmly establishing the extragalactic origin of the UGRB. Intriguingly, the properties inferred for the sources contributing to the UGRB show departures from those of the resolved {\gamma}-ray population, suggesting that the faint end of the $\gamma$-ray sky is not a simple extrapolation of currently resolved sources. - oai:arXiv.org:2601.13312v1 - astro-ph.CO - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - B. Thakore, M. Regis, M. Negro, S. Camera, D. Gruen, N. Fornengo, A. Roodman - - - Combined LOFAR-uGMRT analysis of the diffuse radio emission in the massive clusters Abell 773 and Abell 1351 - https://arxiv.org/abs/2601.13316 - arXiv:2601.13316v1 Announce Type: new -Abstract: Radio halos are megaparsec-scale diffuse, non-thermal radio sources located at the centers of galaxy clusters, tracing relativistic particles and magnetic fields in the intra-cluster medium. Their origin is generally attributed to cluster mergers that generate turbulence and re-accelerate aged electrons. We study the diffuse radio emission, spectral properties, and the connection between thermal and non-thermal components in the massive galaxy clusters Abell 773 and Abell 1351 ($M_{500} \sim 7 \times 10^{14}\,M_{\odot}$), both of which are dynamically disturbed. We combine LOFAR LoTSS-DR2 observations at 144 MHz with uGMRT observations at 650 MHz, supplemented by archival XMM-Newton X-ray imaging. We confirm that both clusters host radio halos extending up to a largest linear size of $\sim 2$ Mpc. We measure an integrated spectral index $\alpha_{144}^{650} \sim -1.0$ for both clusters. The radio halo in Abell 773 resembles a classical halo and follows a sublinear radio--X-ray surface brightness relation. In contrast, Abell 1351 shows a more complex and asymmetric morphology, influenced by embedded radio sources including the brightest cluster galaxy, a tailed radio galaxy, and a ridge-like feature. These contaminating sources lead to deviations from the sublinear trend in the point-to-point radio--X-ray analysis of Abell 1351. - oai:arXiv.org:2601.13316v1 + Constraining dark energy models using Jackknife and Bootstrap resampling + https://arxiv.org/abs/2601.16197 + arXiv:2601.16197v1 Announce Type: new +Abstract: Analyses of type Ia supernovae have helped us shed light on the existence and nature of dark energy. Most of these analyses have relied on Bayesian techniques. In this work, we rely on resampling techniques to analyse supernova data. In particular, we use the generalised least squares method together with Jackknife and Bootstrap techniques to estimate parameters of $\Lambda$CDM, flat $\Lambda$CDM, $w$CDM, flat $w$CDM, and flat $w_0\,w_a$CDM models from the recent PantheonPlus and SH0ES data. For completeness, we also perform Bayesian analysis using Markov chain Monte Carlo (MCMC) and nested sampling algorithms, and compare the results. We note that resampling techniques can help highlight the limitations of the data. For instance, we see that the Jackknife method estimates a strong positive correlation between $h$ and $M$ and higher standard deviations for both. This may have significant implications for the Hubble tension. We conclude with a discussion of our results. + oai:arXiv.org:2601.16197v1 astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - K. S. L. Srikanth, A. Botteon, R. Cassano, G. Brunetti, A. Bonafede, L. Bruno, M. Balboni, H. Bashir, M. Br\"uggen, S. Chatterjee, V. Cuciti, D. Dallacasa, A. Datta, F. de Gasperin, G. Di Gennaro, C. Groeneveld, R. Kale, M. A. Malik, S. Paul, S. Salunkhe, R. J. van Weeren, T. Venturi, X. Zhang - - - The ESA Meerkat Asteroid Guard: a monitoring service for imminent impactors - https://arxiv.org/abs/2601.13323 - arXiv:2601.13323v1 Announce Type: new -Abstract: We present the Meerkat Asteroid Guard, an imminent impactor warning service developed and maintained by the European Space Agency's Near-Earth Object Coordination Centre (NEOCC). The software uses the method of systematic ranging to perform orbit determination on tracklets in the Near-Earth Object Confirmation Page (NEOCP), which typically have short observational arcs. Fitted orbits are propagated to determine the likelihood of an impact with Earth. In addition, magnitude fitting and Monte Carlo sampling are performed to estimate the object's size, possible impact locations and times, and suggest a best telescope pointing for object follow-up. A set of object scores are produced from computed posterior probabilities across the grid, giving a statistical description of the object's orbital and physical characteristics. The scores are packaged with several informative plots in an email alert, which is sent to Meerkat subscribers in the event of a significant impact probability, close approach, or other scientifically interesting event. The highlights of the five years of Meerkat's operational service are presented, including the successful warnings for all of the past six imminent impactors discovered before impact and several interesting close approaches. - oai:arXiv.org:2601.13323v1 - astro-ph.EP - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Charlie Drury, Francesco Gianotto, Marco Fenucci, Laura Faggioli, Michael Fr\"uhauf, Juan Luis Cano, Marco Micheli, Francisco Oca\~na, Dario Oliviero, Luca Conversi, Richard Moissl, Detlef Koschny - - - The DESIRED temperature-metallicity relations in star-forming regions: probing the Galactic radial and azimuthal metallicity distributions - https://arxiv.org/abs/2601.13337 - arXiv:2601.13337v1 Announce Type: new -Abstract: We analyse a sample of 225 star-forming regions from the DESIRED-E project, each with simultaneous determinations of the electron temperature from ionized nitrogen and oxygen, $T_{\rm e}$([NII]) and $T_{\rm e}$([OIII]), respectively. We derive new empirical relations connecting the gas-phase metallicity to the global electron temperature, $T_{\rm e}$(H$^+$), as determined via radio observations. We establish two calibrations: one assuming a homogeneous temperature distribution ($t^2 = 0$, the ``direct method''), and another accounting for internal temperature fluctuations ($t^2 > 0$). Applying these calibrations to 460 radio observations of Galactic HII~regions spanning Galactocentric distances from $\sim0.1$ to 16 kpc, we determine the radial O/H gradient in the Milky Way under both assumptions. We further compare these nebular gradients to independent metallicity estimates from young O- and B-type stars and Cepheid variables. We find that the $t^2 > 0$ calibration yields a gradient in excellent agreement with stellar-based determinations, whereas the $t^2 = 0$ method underestimates metallicities by up to $\sim$0.3 dex. This discrepancy cannot be reconciled by invoking oxygen depletion onto dust grains or nucleosynthetic processing via the CNO cycle in massive stars. We also find that one widely used relation in the literature, assuming $t^2 = 0$, produces an excessively steep gradient -- likely due to the use of outdated atomic data and pre-CCD observations. Finally, we explore potential azimuthal variations in the Galactic metallicity distribution driven by the presence of the spiral arms, finding no evidence for variations larger than $\sim$0.1 dex with respect to the general radial gradient. - oai:arXiv.org:2601.13337v1 - astro-ph.GA - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - I. Rafael Mart\'inez-Hern\'andez, J. Eduardo M\'endez-Delgado, C\'esar Esteban, Jorge Garc\'ia-Rojas, Leticia Carigi, Luis F. Rodr\'iguez, Luis A. Zapata, F. Fabi\'an Rosales-Ortega, Maialen Orte-Garc\'ia, Elena Reyes-Rodr\'iguez, Karla Z. Arellano-C\'ordova, Kathryn Kreckel, Natascha Sattler, Christophe Morisset, Manuel Peimbert, Silvia Torres-Peimbert, Miriam Pe\~na, \v{Z}ofia Chrob\'akov\'a, Eleonora Zari, David A. Espinoza-Galeas - - - Locating the missing large-scale emission in the jet of M87* with short EHT baselines - https://arxiv.org/abs/2601.13356 - arXiv:2601.13356v1 Announce Type: new -Abstract: In Very-Long Baseline Interferometric arrays, nearly co-located stations probe the largest scales and typically cannot resolve the observed source. In the absence of large-scale structure, closure phases constructed with these stations are zero and, since they are independent of station-based errors, they can be used to probe data issues. Here, we show with an expansion about co-located stations, how these trivial closure phases become non-zero with brightness distribution on smaller scales than their short baseline would suggest. When applied to sources that are made up of a bright compact and large-scale diffuse component, the trivial closure phases directly measure the centroid relative to the compact source and higher-order image moments. We present a technique to measure these image moments with minimal model assumptions and validate it on synthetic Event Horizon Telescope (EHT) data. We then apply this technique to 2017 and 2018 EHT observations of M87* and find a weak preference for extended emission in the direction of the large-scale jet. We also apply it to 2021 EHT data and measure the source centroid about 1 mas northwest of the compact ring, consistent with the jet observed at lower frequencies. - oai:arXiv.org:2601.13356v1 - astro-ph.HE - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Boris Georgiev, Paul Tiede, Sebastiano D. von Fellenberg, Michael Janssen, Iniyan Natarajan, Lindy Blackburn, Jongho Park, Erandi Chavez, Andrew T. West, Kotaro Moriyama, Jun Yi Koay, Hendrik M\"uller, Dhanya G. Nair, Avery E. Broderick, Maciek Wielgus, Kazunori Akiyama, Ezequiel Albentosa-Ru\'iz, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovi\'c, Bidisha Bandyopadhyay, John Barrett, Michi Baub\"ock, Bradford A. Benson, Dan Bintley, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Paul Chichura, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Brandon Curd, Rohan Dahale, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Gregory Desvignes, Jason Dexter, Vedant Dhruv, Indu K. Dihingia, Sheperd S. Doeleman, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Edward Fomalont, H. Alyson Ford, Marianna Foschi, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garc\'ia, Olivier Gentaz, Ciriaco Goddi, Roman Gold, Arturo I. G\'omez-Ruiz, Jos\'e L. G\'omez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Britton Jeter, Wu Jiang, Alejandra Jim\'enez-Rosales, Michael D. Johnson, Svetlana Jorstad, Adam C. Jones, Abhishek V. Joshi, Taehyun Jung, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Joana A. Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Deokhyeong Lee, Sang-Sung Lee, Aviad Levis, Shaoling Li, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Amy E. Lowitz, Ru-Sen Lu, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Iv\'an Mart\'i-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Izumi Mizuno, Yosuke Mizuno, Joshua Montgomery, James M. Moran, Monika Moscibrodzka, Wanga Mulaudzi, Cornelia M\"uller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Gopal Narayanan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Chunchong Ni, Michael A. Nowak, Junghwan Oh, Hiroki Okino, H\'ector Ra\'ul Olivares S\'anchez, Tomoaki Oyama, Feryal \"Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pi\'etu, Alexander Plavin, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Giacomo Principe, Dimitrios Psaltis, Hung-Yi Pu, Alexandra Rahlin, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Angelo Ricarte, Luca Ricci, Bart Ripperda, Jan R\"oder, Freek Roelofs, Cristina Romero-Ca\~nizales, Eduardo Ros, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Le\'on D. S. Salas, Salvador S\'anchez, David S\'anchez-Arg\"uelles, Miguel S\'anchez-Portal, Mahito Sasada, Kaushik Satapathy, Saurabh, Tuomas Savolainen, F. Peter Schloerb, Jonathan Schonfeld, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Sasikumar Silpa, Des Small, Randall Smith, Bong Won Sohn, Jason SooHoo, Kamal Souccar, Joshua S. Stanway, He Sun, Fumie Tazaki, Alexandra J. Tetarenko, Remo P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Teresa Toscano, Efthalia Traianou, Tyler Trent, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jasmin E. Washington, Jonathan Weintroub, Robert Wharton, Kaj Wiik, Gunther Witzel, Michael F. Wondrak, George N. Wong, Jompoj Wongphexhauxsorn, Qingwen Wu, Nitika Yadlapalli, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, Andr\'e Young, Ziri Younsi, Wei Yu, Feng Yuan, Ye-Fei Yuan, Ai-Ling Zeng, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, Shan-Shan Zhao - - - The odyssey of the black hole low mass X-ray binary GX339-4: Five years of dense multi-wavelength monitoring - https://arxiv.org/abs/2601.13360 - arXiv:2601.13360v1 Announce Type: new -Abstract: We present the longest and the densest quasi-simultaneous radio, X-ray and optical campaign of the black hole low mass X-ray binary GX339-4, covering five years of weekly GX339-4 monitoring with MeerKAT, Swift-XRT and MeerLICHT, respectively. Complementary high frequency radio data with the Australia Telescope Compact Array are presented to track in more detail the evolution of GX339-4 and its transient ejecta. During the five years, GX339-4 has been through two "hard-only" outbursts and two "full" outbursts, allowing us to densely sample the rise, quenching and re-activation of the compact jets. Strong radio flares were also observed close to the transition between the hard and the soft states. Following the radio flare, a transient optically thin ejection was spatially resolved during the 2020 outburst, and was observed for a month. We also discuss the radio/X-ray correlation of GX339-4 during this five year period, which covers several states in detail from the rising phase to the quiescent state. This campaign allowed us to follow ejection events and provide information on the jet proper motion and its intrinsic velocity. With this work we publicly release the weekly MeerKAT L-band radio maps from data taken between September 2018 and October 2023. - oai:arXiv.org:2601.13360v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - E. Tremou, S. Corbel, R. Fender, P. Woudt, J. C. A Miller-Jones, I. Heywood, F. Carotenuto, S. Motta, A. Tzioumis, P. J. Groot, D. M. Russell, J. Crook-Mansour, P. Saikia, W. Yu, J. van den Eijnden, A. J. van der Horst, D. R. A. Williams-Baldwin, X. Zhang - - - Environment and Gas Fraction in Type-2 AGN versus Non-AGN Galaxies - https://arxiv.org/abs/2601.13375 - arXiv:2601.13375v1 Announce Type: new -Abstract: We investigate the environmental parameters and gas fraction (f$_{gas}$) properties of type~2 AGN and non-AGN galaxies, utilizing a large sample of galaxies from SDSS DR7 with z $\le$ 0.3. We find that the environment affects type~2 AGN and non-AGN galaxies in similar ways and does not impact the strength of AGN-driven outflows. The f$_{gas}$ of type~2 AGN and non-AGN host galaxies show no variation between group and isolated environments, suggesting that host galaxy gas content is largely independent of large-scale environment. We find that type~2 AGN host galaxies possess systematically lower f$_{gas}$ than their non-AGN counterparts when matched in stellar mass and star formation rate (SFR). This suggests that AGN activity plays a significant role in regulating the molecular gas reservoir and, consequently, the star formation processes within galaxies. We find that Type~2 AGNs exhibiting strong outflows are associated with higher gas fractions, higher star-formation rates, and younger stellar populations than those with weak or no outflows. This may indicate either concurrent star formation in gas-rich systems hosting powerful outflows, or a time delay between AGN activity and its effect on star formation consistent with a delayed AGN feedback scenario. - oai:arXiv.org:2601.13375v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jyoti Yadav, Jong-Hak Woo, Ashraf Ayubinia - - - Neutrinos from hidden ultraluminous X-ray sources in the Galaxy - https://arxiv.org/abs/2601.13378 - arXiv:2601.13378v1 Announce Type: new -Abstract: Ultraluminous X-ray sources (ULXs) are point-like sources that exhibit apparent X-ray luminosities exceeding the Eddington limit for stellar-mass compact objects. A widely accepted interpretation is that these systems are X-ray binaries accreting matter possibly at super-Eddington rates. In this regime, photon trapping inflates the accretion disk, making it geometrically and optically thick. Radiation-driven winds launched from the supercritical disk form funnel-shaped walls along the symmetry axis. While the apparent X-ray luminosity can exceed the Eddington limit due to geometrical beaming within this funnel, a misalignment with the observer's line of sight strongly suppresses the X-ray emission, rendering the ULX electromagnetically obscured. - This work explores the potential for high-energy neutrino production in black hole-hosting ULXs. We model proton acceleration via magnetic reconnection in the region above the super-accreting black hole. Although electromagnetic emission is efficiently absorbed by the dense wind and radiation fields, neutrinos generated from photomeson interactions can escape. Our model self-consistently accounts for energy losses of pions and muons in this environment. The results indicate that misaligned, electromagnetically obscured Galactic ULXs could produce a neutrino flux detectable by instruments like KM3NeT and IceCube within several years of observation. - oai:arXiv.org:2601.13378v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Lucas M. Pasquevich, Gustavo E. Romero, Mat\'ias M. Reynoso - - - Probing the kinematics of the Local Group with chemically enriched gas in the Hestia simulations - https://arxiv.org/abs/2601.13382 - arXiv:2601.13382v1 Announce Type: new -Abstract: We present a study of the gas kinematics within the Hestia project, a state-of-the-art set of simulations of the Local Group, with a particular focus on the velocity patterns of different ions and the large-scale motion of gas and galaxies towards the Local Group barycentre. Using two high-resolution Hestia runs, we examine the distribution and velocities of H I, C IV, Si III, O VI, O VII, and O VIII and their imprints on sightlines observed from the Sun's location in different reference frames. To mimic observational strategies, we assess the contribution of rotating disc gas, assuming simple kinematic and geometrical considerations. Our results indicate that local absorption features in observed sightlines most likely trace material in the circumgalactic medium of the Milky Way. Some sightlines, however, show that intragroup material could be more easily observed towards the barycentre, which defines a preferred direction in the sky. In particular, H I, Si III, and C IV roughly trace cold gas inside the Milky Way and Andromeda haloes, as most of their mass flux occurs within the virial region of each galaxy, while oxygen high ions mostly trace hot halo and intragroup gas, with comparable mass fluxes in the Local Group outskirts and the circumgalactic medium of the two main galaxies. Additionally, we find that pressures traced by different ionic species outside the Milky Way halo show systematically higher values towards the barycentre direction in contrast to its antipode in the sky. Kinematic imprints of the global motion towards the barycentre can be seen at larger distances for all ionic species as the Milky Way rams into material in the direction of Andromeda, with gas towards the anti-barycentre lagging behind. - oai:arXiv.org:2601.13382v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - L. Biaus, S. E. Nuza, C. Scannapieco, P. Richter, M. Damle, N. I. Libeskind, M. Vogelsberger - - - Turbulence Can Persist in the Inner Regions of Weakly-Ionized Planet Forming Disks - https://arxiv.org/abs/2601.13391 - arXiv:2601.13391v1 Announce Type: new -Abstract: Identifying the mechanisms responsible for angular momentum transport in protoplanetary disks, and the extent to which those mechanisms produce turbulence, is a crucial problem in understanding planet formation. The bulk of the gas in protoplanetary disks is weakly ionized, which leads to the emergence of three non-ideal effects, Ohmic diffusion, ambipolar diffusion, and the Hall effect. These low-ionization processes can in some cases suppress turbulence driven by the magnetorotational instability (MRI). However, it has recently been shown that these non-ideal terms can also affect the dynamics of the gas in fundamentally different ways than simple diffusion. In order to further study the role of low-ionization on disk gas dynamics, we carry out a 3D local shearing box simulation with both Ohmic diffusion and ambipolar diffusion and an additional simulation with the Hall effect included. The strength of each non-ideal term, when present, is representative of gas at a radius of 5 AU in a realistic protoplanetary disk. We find the Hall effect increases the saturation strength of the magnetic field, but does not necessarily drive turbulence, consistent with previous work. However, interactions between ambipolar diffusion and the Keplerian shear lead to the ambipolar diffusion shear instability (ADSI), which can drive the initial growth, not damping, of magnetic perturbations. To our knowledge, this is the first work that explicitly demonstrates the viability of the ADSI in the non-linear regime within protoplanetary disks. At later times in the disk, the MRI (reduced in strength by ambipolar-diffusion), may also be present in regions of weak magnetic field between strong concentrations of vertical magnetic flux and sustain turbulence locally in protoplanetary disks. - oai:arXiv.org:2601.13391v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - David G. Rea, Jacob B. Simon - - - Discovery of 1H-cyclopent[cd]indene (c-C11H8) in TMC-1 with the QUIJOTE line survey: A new three-ringed polycyclic aromatic hydrocarbon - https://arxiv.org/abs/2601.13403 - arXiv:2601.13403v1 Announce Type: new -Abstract: We report the detection of the polycyclic aromatic hydrocarbon (PAH) 1H-cyclopent[cd]indene (c-C11H8) in TMC-1 with the QUI- JOTE line survey. We detected 22 independent lines corresponding to 88 rotational transitions with quantum numbers ranging from J=19 up to J=24 and Ka <= 5 in the Q-band range. The identification of this new PAH was based on the agreement between the rotational parameters derived from the analysis of the lines and those obtained by quantum chemical calculations. The column density derived for 1H-cyclopent[cd]indene is (6.0 +- 0.5) x 10^12 cm-2, with a rotational temperature of 9 K. Its abundance is high, as is that of the rest of the PAHs, but it is the lowest of all those detected to date in TMC-1, being 2.66 times less abundant than indene and 4.66 times less than phenalene. This result will help us to better understand the growth of five- and six-membered rings in dark clouds. Chemical models explaining their formation through the bottom-up model are still very incomplete and require further experimental and theoretical effort. Even so, the most likely formation reactions would occur between the smallest rings with small hydrocarbons; the most probable reaction for the formation of cyclopentindene is that between indene and C2H, C2H3, and/or their cation. - oai:arXiv.org:2601.13403v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - R. Fuentetaja, C. Cabezas, M. Ag\'undez, B. Tercero, N. Marcelino, P. de Vicente, J. Cernicharo - - - Mass density structuring around galaxy formation sites: impact on galaxy basic properties - https://arxiv.org/abs/2601.13431 - arXiv:2601.13431v1 Announce Type: new -Abstract: We study the local evolution of the Universe around galaxy formation sites in the EAGLE50 large-volume reference simulation. Using the reduced inertia tensor (r-TOI), we followed the anisotropic evolution of initially spherical Lagrangian volumes (LVs) centred at galaxy formation sites, both in dark matter (DM) and in cold baryons (CB), from very high redshift $z=15$ onward. We describe LV deformation in terms of the r-TOI eigen-directions, principal axes, their derived shape parameters, and the timescales for the freezing-out of these principal directions and axes. Of particular interest are the age of the Universe, $t_{\rm U}$, when the local Cosmic Web (CW) spine emerges, and that when anisotropic DM mass arrangements (i.e., migrant mass flows) cease. We find that the shapes LVs acquire along their evolution affect the halo and stellar mass of their central galaxy: prolate-shaped LVs show a tendency to host low-mass galaxies at $z=0$, while massive galaxies tend to form within triaxial or oblate LVs. Also, the local CW spine tends to set in earlier on in LVs that are to host massive galaxies than in those harbouring less massive galaxies. In addition, anisotropic DM-mass rearrangements stop late on average, at $t_{\rm U}\sim 10.5\,$Gyr, and even slightly later for CB. Interestingly, $z=0$ LVs with either flattened configurations in CB or those that are highly prolate in DM, are more likely to host rotation-dominated galaxies. This effect increases from $z=1$ to $z=0$. Finally, the CB spine of LVs that are more likely to host rotation-dominated galaxies emerges at later times. - oai:arXiv.org:2601.13431v1 - astro-ph.GA - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Sandra Robles, Rosa Dom\'inguez-Tenreiro, Susana E. Pedrosa - - - A dual tunnel structure for the Einstein Telescope - https://arxiv.org/abs/2601.13438 - arXiv:2601.13438v1 Announce Type: new -Abstract: We present a novel tunnel architecture for the Einstein Telescope that departs from the traditional large-cavern approach and reduces the excavated volume by an order of magnitude. In the proposed design, all seismic isolation systems are housed in raise-bore wells drilled upward from the main tunnel toward an upper service tunnel. The pre-isolators for the most sensitive optics are located in the service tunnel, seating directly on strong and compact rock, while the other filters are distributed along the wells within compact, side-access vacuum chambers. Shorter, separate wells accommodate the seismic isolation systems for less demanding optics. This configuration provides substantial advantages: easier lock acquisition and improved robustness of the interferometers, lower-frequency pendulum stages, reduced congestion around the test masses, simplified installation and maintenance, improved vacuum partitioning, strong physical decoupling between the high- and low-frequency interferometers, and enhanced compatibility with future advances of Newtonian-noise cancellation. A novel technique for real-time, precision monitoring of rock motion and tilt provides a new signal for Newtonian noise cancellation and enables correction of seismic disturbances even during earthquakes, offering unique geophysical measurement capabilities. - oai:arXiv.org:2601.13438v1 - astro-ph.IM - gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Riccardo DeSalvo, Emerald Gingell, Jes\'us Leonardo Gonz\'alez L\'opez, Nelson Leon, Marina Mondin, Harry Themann, Fabi\'an Erasmo Pe\~na Arellano + Roshna K, Nikhil Fernandes, P Praveen, V. Sreenath - Observations with the Southern Connecticut Stellar Interferometer. II. First Three-Telescope Observations and a New Diameter Measurement of Arcturus - https://arxiv.org/abs/2601.13447 - arXiv:2601.13447v1 Announce Type: new -Abstract: We discuss the most recent observations made with the Southern Connecticut Stellar Interferometer (SCSI), which is a three-station stellar intensity interferometer located on the campus of Southern Connecticut State University, in New Haven, Connecticut. Two different kinds of observations are presented. We first analyze observations of Vega taken in a three-telescope mode. (Previously, the instrument had only two operational stations.) We show that, while the efficiency remains nearly identical to that reported in our last paper, the addition of the third station allows more photon data to be recorded simultaneously, and therefore we can build up the photon-bunching peak in the data stream in fewer hours on sky for an unresolved source. In the second part of the paper, we report our observations to date of the nearby red giant star, Arcturus, most of which occurred in the first half of 2025. These show that, as a partially resolved source at the baselines we used, we detect fewercorrelations in the photon-bunching peak than for an unresolved source of comparable brightness. Combining the data with speckle imaging observations taken at Apache Point Observatory, we derive a new measurement of Arcturus' diameter that extends the time baseline of interferometric observations of the star and is consistent with previous analyses made by other investigators. - oai:arXiv.org:2601.13447v1 - astro-ph.IM + A multiwavelength ALMA view of gas and dust in binary protoplanetary system AS 205: Evidence of dust asymmetric distribution + https://arxiv.org/abs/2601.16202 + arXiv:2601.16202v1 Announce Type: new +Abstract: We present Atacama Large Millimeter/Submillimeter Array observations of multi-wavelength dust emissions at 3.1\,mm and 1.3\,mm; along with molecular line emissions of CO(2--1), CO(3--2), \mbox{$^{13}$CO(3--2)}, and C$^{18}$O(3--2) at spatial resolutions of 7--45 AU towards the protoplanetary system AS 205. The dust emissions exhibit two distinct components of AS 205 N and AS 205 S, separated by 1.3 arcsec. While gas kinematics within the dust disk regions are dominated by Keplerian rotation, the more extended gas emission displays complex morphology and kinematics strongly affected by the binary gravitational interaction in the outer regions. The stellar masses of AS 205 N and AS 205 S are estimated at $0.78\pm0.19$\,M$_\odot$ and $1.93\pm0.86$\,M$_\odot$, respectively. Azimuthal variation is observed in the spectral index distribution of both disks. In AS 205 N, the spectral index minimum in the southwest is coincident with the peaks of CO($2-1$), CO($3-2$), and $^{13}$CO($3-2$) integrated intensity and the relative position of its southern counterpart. On the other hand, the spectral index distribution in \ass~exhibits two prominent maxima, with the one in the northeast aligning with the peak of $^{13}$CO($3-2$), and the peak in the south coinciding with local maxima in CO($2-1$) and CO($3-2$) azimuthal profiles. These results suggest a correlation between dust grain size and/or optical depth with the gas distributions. Dust-trapping along the spiral arms possibly contributes to the spectral index minima in AS 205 N; however, the observed asymmetry across both disks suggests the involvement of additional mechanisms. + oai:arXiv.org:2601.16202v1 astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Elliott P. Horch, Sebastian M. Lucero, Max Martone, Riley C. Barrett, Ana I. Baculima Dur\'an, Fiona T. Powers \"Ozyurt, Gage Posick, Alexander Petroski, James W. Davidson, Jr., Steven R. Majewski, Richard A. Pellegrino, Paul M. Klaucke, Xavier Lesley-Salda\~na, Torrie Sutherland, Olivia S. Weiss - - - Four Cold Super-Jupiters Revealed by Extended and Complex Microlensing Signals - https://arxiv.org/abs/2601.13450 - arXiv:2601.13450v1 Announce Type: new -Abstract: We present the analysis of four microlensing events, KMT-2020-BLG-0202, KMT-2022-BLG-1551, KMT-2023-BLG-0466, and KMT-2025-BLG-0121, which exhibit extended and complex anomalies in their light curves. These events were identified through a systematic reanalysis of KMTNet data aimed at detecting planetary signals that deviate from the typical short-term anomaly morphology. Detailed modeling indicates that all four anomalies were produced by planetary companions to low-mass stellar hosts. The events have mass ratios of $q \sim (5$--$14)\times10^{-3}$ and Einstein timescales of $t_{\rm E} \sim 20$--$43$ days. Bayesian analyses based on Galactic models show that the companions are super-Jupiters with masses of a few to approximately 10 $M_{\rm J}$, orbiting sub-solar-mass hosts located at distances of $D_{\rm L} \sim 4$--$7$~kpc. All planets lie well beyond the snow line of their hosts, placing them in the regime of cold giant planets. These detections demonstrate that extended and complex microlensing anomalies, which are often challenging to recognize as planetary in origin, can nonetheless contain planetary signals. This work underscores the unique sensitivity of microlensing to cold, massive planets beyond the snow line and highlights the importance of systematic reanalyses of survey data for achieving a more complete and unbiased census of exoplanets in the Galaxy. - oai:arXiv.org:2601.13450v1 astro-ph.EP - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Cheongho Han, Chung-Uk Lee, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Youn Kil Jung, Kyu-Ha Hwang, Yoon-Hyun Ryu, Yossi Shvartzvald, In-Gu Shin, Jennifer C. Yee, Weicheng Zang, Hongjing Yang, Doeon Kim, Dong-Jin Kim, Sang-Mok Cha, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge + Nguyen Thi Phuong, Nguyen Tat Thang - The Relationship between Accretion and Ionised Ejection among Young Stellar Objects in the Coronet Cluster - https://arxiv.org/abs/2601.13459 - arXiv:2601.13459v1 Announce Type: new -Abstract: We present results from a coordinated, multi-epoch near-infrared and centimeter radio survey of young stellar objects (YSOs) in the Coronet, aimed at probing the connection between mass accretion and ionised mass loss. Using VLT-KMOS, we detect Br$\gamma$ emission in 5 of the 26 targets, which also exhibit 3.3-cm continuum emission in VLA images, consistent with partially ionised jets. For seven additional sources, stringent flux upper limits were obtained. The derived accretion and ionised mass-loss rates for class I and class II YSOs follow a sublinear correlation $\dot{M}_{\mathrm{ion}} \propto \dot{M}_{\mathrm{acc}}^{0.3}$, consistent with previous results for class II YSOs but extended here to earlier stages. Multi-epoch observations reveal modest variability in both tracers but no clear temporal correlation between accretion and ejection within timescales of a few months. The ratio $\dot{M}_{\mathrm{ion}}/\dot{M}_{\mathrm{acc}}$ shows an anti-correlation with $\dot{M}_{\mathrm{acc}}$, increasing with time from class I YSOs to class II YSOs, suggesting an increase in jet-launching efficiency or ionisation fraction with evolution. These findings support a direct connection between accretion and outflow across the $\sim$ Myr timescale of YSO evolution, while highlighting the complexity of their short-term interplay. - oai:arXiv.org:2601.13459v1 + Cyclic sunspot activity during the first millennium CE as reconstructed from radiocarbon + https://arxiv.org/abs/2601.16203 + arXiv:2601.16203v1 Announce Type: new +Abstract: Context. Solar activity, dominated by the 11-year cyclic evolution, has been observed directly since 1610. Before that, indirect cosmogenic proxy data are used to reconstruct it over millennia. Recently, the precision of radiocarbon measurements has improved sufficiently to allow reconstructing solar activity over millennia. Aims. The first detailed reconstruction of solar activity, represented by annual sunspot numbers, is presented for 1-969 CE. Methods. The reconstruction of sunspot numbers from D14C was performed using a physics-based method involving several steps: using a carbon-cycle box model, the 14C production rate, corrected for the geomagnetic shielding, was computed from the measured data; The open solar magnetic flux was computed using a model of the heliospheric cosmic-ray modulation; Sunspot numbers were calculated using a model of the evolution of the Sun's magnetic field. The Markov Chain Monte Carlo approach was used to account for different sources of uncertainty. Results. Annual sunspot numbers were reconstructed for the first millennium CE. This period includes one extreme solar event of 774 CE and one Grand solar minimum of 650-730 CE. We could identify 91 solar cycles, of which 26 were well-defined, while 24 and 41 were reasonably and poorly defined, respectively. The mean cycle length was 10.6 years, but the lengths of individual cycles vary between 8 and 15 years. The existence of empirical Waldmeier's relations remains inconclusive. No significant periodicities were found beyond the 11-year cycle. Conclusions. This work fills the gap in the solar cycle statistics between the previously reconstructed first millennium BCE and the second millennium CE, providing vital constraints for the solar dynamo and irradiance models. A consistent 3-millennium-long reconstruction of sunspot numbers, based on a composite multi-proxy cosmogenic record, is pending. + oai:arXiv.org:2601.16203v1 astro-ph.SR - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/publicdomain/zero/1.0/ - Arpan Ghosh, Roberto Galv\'an-Madrid, Johanan Ram\'irez-Arellano, Carlos Carrasco-Gonz\'alez, Gr\'ainne Costigan, Suzanne Ramsay, Carlo Manara, Jan Forbrich, Hauyu Baobab Liu, Michihiro Takami - - - Magnetic field morphological diagnostics with ALMA in the G327.29 protocluster: VGT versus dust polarization - https://arxiv.org/abs/2601.13473 - arXiv:2601.13473v1 Announce Type: new -Abstract: Magnetic fields and turbulence may play a key role in the evolution of protoclusters, influencing the formation of dense cores and stars. Here, we examine the morphology of the magnetic fields in the G327.29 protocluster using both the velocity gradient technique (VGT) extracted from molecular line emissions and linear polarization in the dust continuum emission. The VGT analysis is performed using four molecular tracers: DCN (3-2), C18O (2-1), HN13C (3-2), and H13CO+ (3-2) - which probe gas across different density regimes, observed with the ALMA 12 m array. Owing to its sensitivity to gas dynamics, a comparison between VGT and dust polarization provides a powerful probe of the evolutionary processes in massive star-forming regions. From our analysis we reveal a complex magnetic-field structure, shaped by the combined influence of turbulence and gravity. In addition, it also appears that there is a large-scale (beyond the core scale) gravitational infall from the surrounding medium on to the filament and the central densest region. Furthermore, we observe that cores are dominated by a mix of turbulence and gravity. Overall, this work presents, likely for the first time, the application of VGT to a massive protocluster, G327.29, using high-resolution ALMA observations. - oai:arXiv.org:2601.13473v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - A. Koley, A. M. Stutz, A. Lazarian, Y. Hu, P. Sanhueza, P. Saha, R. H. Alvarez-Gutierrez, N. S. Sandoval-Garrido, N. Castro-Toledo, G. Bernal Mesina - - - Architectures of Exoplanetary Systems. IV: A Multi-planet Model for Reproducing the Radius Valley and Intra-system Size Similarity of Planets around Kepler's FGK Dwarfs - https://arxiv.org/abs/2601.13480 - arXiv:2601.13480v1 Announce Type: new -Abstract: The Kepler-observed distribution of planet sizes have revealed two distinct patterns: (1) a radius valley separating super-Earths and sub-Neptunes and (2) a preference for intra-system size similarity. We present a new model for the exoplanet population observed by Kepler, which is a "hybrid" of a clustered multi-planet model in which the orbital architectures are set by the angular momentum deficit (AMD) stability (He et al. 2020; arXiv:2007.14473) and a joint mass-radius-period model involving envelope mass-loss driven by photoevaporation (Neil & Rogers 2020; arXiv:1911.03582). We find that the models that produce the deepest radius valleys have a primordial population of planets with initial radii peaking at $\sim 2.1 R_\oplus$, which is subsequently sculpted by photoevaporation into a bimodal distribution of final planet radii. The hybrid model requires strongly clustered initial planet masses in order to match the distributions of the size similarity metrics. Thus, the preference for intra-system radius similarity is well explained by a clustering in the primordial mass distribution. The hybrid model also naturally reproduces the observed radius cliff (steep drop-off beyond $\sim 2.5 R_\oplus$). Our hybrid model is the latest installment of the SysSim forward models, and is the first multi-planet model capable of simultaneously reproducing the observed radius valley and the intra-system size similarity patterns. We compute occurrence rates and fractions of stars with planets for a variety of planet types, and find that the occurrence of Venus and Earth-like planets drops by a factor of $\sim 2$-4 for the hybrid models compared to previous clustered models in which there is no envelope mass-loss. - oai:arXiv.org:2601.13480v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Matthias Y. He, Eric B. Ford - - - Initial Investigations of the Outskirts of XLSSC 122 - https://arxiv.org/abs/2601.13492 - arXiv:2601.13492v1 Announce Type: new -Abstract: We investigate the redshift 1.98 galaxy cluster XLSSC 122 using the Hubble Space Telescope (HST) from the core of the cluster out to 3 Mpc, a scale equivalent to 10 times the R500 = 295 kpc radius. We present an expanded photometric and spectroscopic catalogue of the cluster, bringing the total number of spectroscopically classified member galaxies to 74, with 35 new member galaxies added in the outer regions of the cluster. We compute the radial galaxy number density profile in the cluster, and observe no clear evidence of infalling groups or cosmic filaments. We observe a clear bimodal colour relation in member galaxies, with red fraction increasing towards the cluster centre. This rapid increase of red fraction upon infall is indicative of a fast quenching mechanism, such as ram pressure stripping, as galaxies enter the cluster centre. We fit a luminosity function to the cluster members, finding a similar low mass slope but fainter scale magnitude than z = 1 clusters of similar temperature, implying a similar galaxy evolution rate to clusters at lower redshift. - oai:arXiv.org:2601.13492v1 - astro-ph.GA - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Eleanore. B. Todd, Jon. P. Willis, Rebecca. E. A. Canning, Oph\'elie. K. Leste, Rahma. Alfarsy, Steven W. Allen, Gabriel Brammer, Joseph. N. Burchett, Adam. B. Mantz, Spencer. A. Stanford - - - c-C3H2 deuteration towards prestellar and starless cores in the Perseus Molecular Cloud - https://arxiv.org/abs/2601.13495 - arXiv:2601.13495v1 Announce Type: new -Abstract: Deuterium fractionation becomes highly efficient in cold, dense cores where CO is frozen out. Cyclopropenylidene (c-C3H2), an early-formed carbon ring, and its deuterated isotopologues trace gas-phase deuteration in these environments. We present a statistical study of c-C3H2 deuteration in starless and prestellar cores of the Perseus Molecular Cloud using observations of c-C3H2, c-C3HD and c-C3D2 obtained with the Yebes 40 m, ARO 12 m and IRAM 30 m telescopes towards 16 cores. Gaussian fits and RADEX modeling yield column densities for the detected species. c-C3H2 is detected in 14/15 covered cores, c-C3HD in 15/16, and c-C3D2 in 9/16. Derived column densities range from 0.5-8.1 x 10^{13} cm^{-2} for c-C3H2, 0.2-2.1 x 10^{12} cm^{-2} for c-C3HD, and 0.6-1.6 x 10^{11} cm^{-2} for c-C3D2. The ortho-to-para ratio of c-C3H2 is obtained for all but one core, with a median value of 3.5\pm0.4. Statistically corrected D/H ratios span 0.5-9.2% (median 1.5\pm0.2%), and D2/D ratios 9-55% (median 25.9\pm4.3%). No trend is found between the c-C3H2 ortho-to-para ratio and core evolutionary stage traced by n(H2). The median D/H ratio in Perseus appears lower than values reported for Taurus and Chamaeleon, while the D2/D ratio agrees with Taurus within uncertainties. A positive correlation between D/H and n(H2) supports the use of D/H as an evolutionary tracer. D2/D does not correlate with n(H2), but shows a positive correlation with T_{kin}, suggesting that its formation is influenced by a mildly endothermic pathway. - oai:arXiv.org:2601.13495v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - J. Ferrer Asensio, S. Scibelli, L. Steffes, B. Kulterer, A. Pokorny-Yadav, Y. Shirley, A. Meg\'ias, I. Jim\'enez-Serra, A. Taillard - - - MIU2Net: weak-lensing mass inversion using deep learning with nested U-structures - https://arxiv.org/abs/2601.13538 - arXiv:2601.13538v1 Announce Type: new -Abstract: One of the primary goals of next-generation gravitational lensing surveys is to measure the large-scale distribution of dark matter, which requires accurate mass inversion to convert weak-lensing shear maps into convergence (kappa) fields. This work develops a mass inversion method tailored for upcoming space missions such as CSST and Euclid, aiming to recover both the mass distribution and the convergence power spectrum with high fidelity. We introduce MIU2Net, a versatile deep-learning framework for kappa-map reconstruction based on the U2-Net architecture. A new loss function is constructed to jointly estimate the convergence field and its frequency-domain energy distribution, effectively balancing optimal mean squared error and optimal power-spectrum recovery. The method incorporates realistic observational effects into shear fields, including shape noise, reduced shear, and complex masks. Under noise levels anticipated for future space-based lensing surveys, MIU2Net recovers the convergence power spectrum with 4% uncertainties up to l approximately 500, significantly outperforming Wiener filtering and MCALens. Beyond two-point statistics, the method accurately reconstructs the convergence distribution, peak centroid, and peak amplitude. Compared to other learning-based approaches such as DeepMass, MIU2Net reduces the root-mean-square error by 5% without smoothing and by 38% with a 1-arcmin smoothing scale. MIU2Net represents a substantial advancement in mass inversion methodology, offering improved accuracy in both RMSE and power-spectrum reconstruction. It provides a promising tool for mapping dark matter environments and large-scale structures in the era of next-generation space lensing surveys. - oai:arXiv.org:2601.13538v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Han W. G., An Zhao, Xinyue Chen, Ran Li, Rui Li, Xiangkun Liu, Zhao Chen, Yu Yu - - - Observational Relationship between Spectral Properties of Gamma-ray and X-ray Emissions from Pulsars - https://arxiv.org/abs/2601.13557 - arXiv:2601.13557v1 Announce Type: new -Abstract: Correlations between gamma-ray and X-ray spectral properties of pulsars are investigated in order to provide observational hints on physics involved in pulsars' high-energy emissions. Using a sample of 43 pulsars detected in both X-ray and gamma-ray bands, we find that pulsars' gamma-ray luminosity, $L_\gamma$, clearly correlates with the luminosity of non-thermal X-ray emission, $L_{\rm p}$, and anti-correlates with non-thermal X-ray photon index. Other gamma-ray spectral parameters show weaker or negligible correlations. The found relation that $L_\gamma \propto L_{\rm p}^{0.49\pm 0.05}$ implies a certain connection between radiation mechanisms and energy distributions of radiating particles for these high-energy emissions. Pulsars with and without detected thermal emissions seem to show different dependencies in those correlations, suggesting the possible existence of two different kinds of pulsars. The ones without detected thermal emissions may represent a population of pulsars with low surface temperature. The origin and energetics of high-energy emitting electron-positron pairs for this group of pulsars probably do not depend on their surface thermal emissions, while that of the other group do. The low surface temperatures might be evidence for the working of some exotic processes of neutron-star cooling. Similar to $L_{\rm p}$, some tempting relationships are found among each gamma-ray spectral parameter, surface temperature and thermally radiating area radius. It again strengthens the connection between gamma-ray and X-ray emissions from pulsars. - oai:arXiv.org:2601.13557v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ashwin Aravindaraj, Hsiang-Kuang Chang + Ilya Usoskin, Sami K. Solanki, Natalie A. Krivova, Theodosis Chatzistergos Dynamical Origin of (469219) Kamo`oalewa of Tianwen-2 Mission from the Main-Belt: $\nu_6$ Secular Resonance, Flora Family or 3:1 Resonance with Jupiter https://arxiv.org/abs/2601.13585 - arXiv:2601.13585v1 Announce Type: new + arXiv:2601.13585v1 Announce Type: cross Abstract: China's Tianwen-2 mission, launched on 29 May 2025, targets the near-Earth object (469219) Kamo`oalewa, an Earth quasi-satellite trapped in a 1:1 mean-motion resonance with our planet. Determining the origin of Kamo`oalewa is central to understanding the formation pathways and dynamical evolution of Earth's quasi-satellite population. Here we show a strong possibility of main-belt origin for Kamo`oalewa using long-term dynamical simulations. We examine three candidate source regions: the $\nu_6$ secular resonance ($\nu_6$), the 3:1 mean-motion resonance with Jupiter (3:1J MMR), and the Flora family. A total of 42,825 test particles were integrated over 100 Myr. We find that asteroids from all three regions can be transported onto Kamo`oalewa-like orbits, albeit with markedly different efficiencies. Particles originating near the $\nu_6$ show the highest transfer probability (3.31%), followed by the Flora family (2.54%) and the 3:1J MMR (0.39%). We further identify representative dynamical pathways linking these source regions to Earth quasi-satellite orbits. The Tianwen-2 spacecraft is expected to rendezvous with Kamo`oalewa in 2026, performing close-proximity operations and returning samples. The mission will provide decisive observational constraints on the asteroid's composition and physical properties, offering a critical test of its proposed origin. oai:arXiv.org:2601.13585v1 astro-ph.EP + astro-ph.HE + astro-ph.IM astro-ph.SR physics.space-ph - Wed, 21 Jan 2026 00:00:00 -0500 - new + Fri, 23 Jan 2026 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Yandong Wang, Shoucun Hu, Jianghui Ji, Jiajun Ying - The R2Pub Telescopes for Surveying: An Overview and Performance Evaluation of the System - https://arxiv.org/abs/2601.13587 - arXiv:2601.13587v1 Announce Type: new -Abstract: The R2Pub telescope, built by the Beijing Planetarium, is a 60 cm equatorial binocular telescope located at the Daocheng site of Yunnan Observatories in China, at an altitude of about 4700 m. This paper presents an overview of the R2Pub telescope system, including its design, instrumentation, and survey capabilities, and reports an initial evaluation of its system performance. R2Pub is a prime-focus binocular system, with each optical tube covering a field of view of approximately 18 square degrees. It is designed to detect a wide range of transient and variable sources in the local universe, such as variable stars, eclipsing binaries, supernovae, gamma-ray burst afterglows, tidal disruption events, active galactic nuclei, and other unknown transients. The observatory infrastructure, including the dome, equatorial mount, optical tubes, and associated subsystems, has been fully constructed and installed, and the system has entered the commissioning phase. Benefiting from the high-altitude location, good seeing conditions, and dark sky background at the Daocheng site, performance tests during commissioning show that the R2Pub system can reach a 5-sigma limiting magnitude of about 18.7 mag in the Pan-STARRS r' band with a 60 s exposure. Ongoing observations with R2Pub are expected to contribute to studies of variable and transient phenomena and to enhance public outreach in astronomy. The binocular design enables simultaneous dual-band observations, providing instantaneous color information for transient sources and improving the classification and physical characterization of their properties and evolution. - oai:arXiv.org:2601.13587v1 - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xuan Song, Xiaofeng Wang, Jin Zhu, Jian Li, Jincheng Guo, Danfeng Xiang, Xin Li, Cheng Liu, Yuanhang Ning, Zhishuai Ge, Zhenzhen Shao, Xiaochen Zheng, Yi Yang, Lei Zhang, Yaqing Shi, Dongyao Zhao, Xiangyun Zeng, Jun Mo, Tengfei Song, Yufeng Fan, Yu Liu, Jingxing Wang, Shousheng He, Ciren Wangdui, Jujia Zhang, Xuefei Zhang, Kai Ye, Jinming Bai, Xiaojun Jiang, Xiaoming Zhang, Peng Qiu, Jicheng Zhang - - - The Structure of an 80 pc Long Massive Filament - https://arxiv.org/abs/2601.13616 - arXiv:2601.13616v1 Announce Type: new -Abstract: Using new Institut de Radioastronomie Millim\'etrique (IRAM) 30m telescope $\rm N_2H^+$, $\rm C^{18}O$ $J$=1-0 and Atacama Pathfinder Experiment (APEX) telescope $\rm ^{13}CO$ and $\rm C^{18}O$ $J$=2-1 maps together with archival far-infrared continuum data, and $\rm ^{12}CO$, and $\rm ^{13}CO$ $J$=1-0 data, we present a comprehensive analysis of the massive filament CFG024.00$+$0.48 (G24) across clump-to-cloud scales. Our results show that G24 is an $\sim$80 pc giant filament with a total mass of $\sim$$10^5$ M$_{\odot}$. In the different tracers the filament width is measured to be about $\sim$2 times the beam size of the observations, as expected for power-law density distributions, giving beam-deconvolved widths in the range from 0.8 to 2.8 pc. We determine a line-of-sight thickness of $\sim$2.2 pc demonstrating that G24 is not an edge-on, flatten structure. The virial parameter obtained from line mass ($\alpha_{\rm line,vir}=M_{\rm line,vir}/M_{\rm line}$) from the $\rm C^{18}O$ (1-0) data is 0.85, and that obtained from $Herschel$-based H$_2$ column density is 0.52, suggesting G24 is globally close to virial equilibrium. The distribution of the 40 dust clumps appears to have a ''two-tier'' fragmentation pattern. For the clump groups, the separation, with a mean/median of 3.68/3.46 pc, is very close to expected length associated with the maximum fragmentation growth rate of $\lambda_{\rm max}=3.55 \pm0.32$ pc estimated for the dust. However, the longitudinal centroid velocity profiles of $\rm C^{18}O$ and $\rm N_2H^+$ show oscillation patterns with wavelengths of 9.8$\pm$0.1 pc and 9.9$\pm$0.1 pc, respectively. This is $\sim$2 times larger than the corresponding values of $\lambda_{\rm max}$ of 4.96$\pm$0.63 pc and 4.65$\pm$1.34 pc, respectively. This suggests that the velocity structure is not dominated by flows directly associated with the fragmentation seen in the dust emission. - oai:arXiv.org:2601.13616v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Qian-Ru He, Won-Ju Kim, Gary A. Fuller, Alessio Traficante, Seamus D. Clarke, Yu Gao, Xue-Peng Chen, Min Fang, Ke Wang, En Chen, Tapas Baug, Xiao-Long Wang, Chen Wang, Yong-Xiong Wang - - - Joint constraints on cosmic birefringence and early dark energy from ACT, Planck, DESI, and PantheonPlus - https://arxiv.org/abs/2601.13624 - arXiv:2601.13624v1 Announce Type: new -Abstract: With the increasing number of high-precision astronomical observations, physical quantities that were previously inaccessible to accurate calculations, such as cosmic birefringence, have once again become a focal point of interest. Such phenomena induce a nonvanishing cross-correlation between the $E$- and $B$-mode polarizations of the cosmic microwave background (CMB), thereby providing a direct observational signature of parity violation. The Chern-Simons coupling between the scalar field in early dark energy (EDE) models and CMB photons is regarded as a plausible mechanism for generating cosmic birefringence. Recent data from the Atacama Cosmology Telescope (ACT) deliver $EB$ measurements at higher multipole moments than those previously achieved by {Planck}, while DESI and PantheonPlus datasets provide new and stringent constraints on the late-time expansion history. Using a joint analysis of {Planck}, DESI DR1, Pantheon+, and ACT data, we perform a full-parameter constraint on the cosmic birefringence effects induced by the EDE-CMB photon coupling. Our results favor a higher Hubble constant, $H_0 = 76.9^{+2.9}_{-2.5}\,\rm km\,s^{-1}\,Mpc^{-1}$, and a relatively large EDE fraction, $f_{\mathrm{EDE}} = 0.232^{+0.074}_{-0.047}$. By comparing the cosmological evolution of this model across different data combinations, we find that the ACT-$EB$ data combined with {Planck} + DESI + PantheonPlus provide good constraints to both early- and late-Universe observations. - oai:arXiv.org:2601.13624v1 - astro-ph.CO - gr-qc + Gravitational Waves and Primordial Black Holes produced by Dark Meta Stable Vacuum Decay + https://arxiv.org/abs/2601.14366 + arXiv:2601.14366v1 Announce Type: cross +Abstract: Inspired by string theory and cosmological constant problem, it is plausible that the Universe's vacuum structure is characterized by a landscape of metastable vacua. The existence of dark matter and dark energy further suggests that the dark sector may inhabit its own "dark landscape". If the dark vacuum is metastable, bubbles of lower-energy phases can nucleate at an approximately constant rate. Because the Hubble expansion rate is monotonically non-increasing with cosmic time, such nucleation can eventually lead to percolation and completion of a dark-sector phase transition. In this work, we investigate the phenomenological consequences of this transition, focusing on the resulting stochastic gravitational-wave background and the potential formation of primordial black holes. We find that the gravitational wave spectrum peaks at $k_{\mathrm{peak}}=3.1 H_{\mathrm{PT}}$, with an amplitude $\Omega_{\mathrm{GW}}^{\mathrm{peak}}\simeq1.5 \Omega_\gamma(\Delta\rho/\rho_{\mathrm{tot}})^2$. Furthermore, the formation of primordial black holes is suppressed due to $\Delta N_{\mathrm{eff}}$ constraint. + oai:arXiv.org:2601.14366v1 hep-ph - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Lu Yin, Guo-Hong Du, Tian-Nuo Li, Xin Zhang - - - HD 26172: an active solar-type subgiant in a close binary system - https://arxiv.org/abs/2601.13652 - arXiv:2601.13652v1 Announce Type: new -Abstract: We present the first comprehensive photometric and spectroscopic analysis of the RS CVn system HD 26172, robustly determining the previously debated evolutionary state of its primary star. Since this system is a single-lined spectroscopic binary with spot-induced light curve modulations, we derived its physical parameters by combining the TESS light curves, the radial velocity curve from our observations, and the primary-star mass estimates based on three complementary methods.Our results reveal that HD 26172 is a detached binary system composed of a $1.25 \pm 0.32 M_{\odot}$ subgiant and a $0.63 \pm 0.11 M_{\odot}$ main-sequence star. The conclusion of subgiant primary is also supported by the absence of lithium absorption and no observed infrared excess. Using long-term photometry from the KWS survey, we detected a tentative stellar activity cycle of 5635 days with an amplitude of 0.04 mag in HD 26172. Additionally, we identified ten optical flare events exhibiting temporally clustered outburst behavior. The presence of a long-term activity cycle, pronounced starspot activity, and frequent optical flares makes HD 26172 a valuable laboratory for studying magnetic activity in subgiants within close binary systems. - oai:arXiv.org:2601.13652v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - 10.1093/mnras/staf2257 - Monthly Notices of the Royal Astronomical Society, Volume 545, Issue 4, id.staf2257, Published February 2026 - Fang-Bin Meng, Li-Ying Zhu, Sheng-Bang Qian, Nian-Ping Liu, Jia Zhang, David Mkrtichian, Soonthornthum Boonrucksar, Er-Gang Zha - - - Possible time-variable iron-K$\alpha$ emission in the circum-nuclear region of the Circinus galaxy - https://arxiv.org/abs/2601.13660 - arXiv:2601.13660v1 Announce Type: new -Abstract: We present imaging and spatially resolved spectral analyses of eight Chandra data taken for the Circinus galaxy in $\approx$ 22 years to reveal neutral iron-K$\alpha$ emission on a circumnuclear scale ($\sim$ 10--100 pc) and search for time variability in the emission. By simulating and taking account of point-source emission from the active galactic nucleus (AGN), we detect iron-line emission $\sim$ 20--60 pc away from the nucleus, particularly in the eastern and western regions. In the two regions, possible time variability in the line flux was also detected. Our spectral analysis then finds that the observed equivalent widths can reach $\sim$ 2 keV and the slopes of underlying continua are rather inverted with $\Gamma < 0$. These are consistent with a scenario in which the iron emission originates from clouds illuminated by AGN X-rays; our result could provide the first extragalactic example of AGN X-ray echoes. In this scenario, we estimated the physical sizes of the illuminated clouds based on the timescale of variability to be less than 6 pc. Furthermore, we compared the iron emission distribution with the cold molecular distribution inferred by Atacama Large Millimeter/submillimeter Array (ALMA) observation of CO($J$=3--2), revealing that in the region of bright iron-line emission, the molecular emission seems to be weak. This might suggest that the AGN X-ray emission affects the chemical composition in the form of AGN feedback. - oai:arXiv.org:2601.13660v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Aiko Miyamoto (The University of Osaka), Taiki Kawamuro (The University of Osaka), Hirokazu Odaka (The University of Osaka), Takuma Izumi (National Astronomical Observatory of Japan), Hironori Matsumoto (The University of Osaka) - - - The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) II. The radial structure of debris discs - https://arxiv.org/abs/2601.13670 - arXiv:2601.13670v1 Announce Type: new -Abstract: The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) was recently completed to cover the lack of high-resolution observations of debris discs and to investigate the prevalence of substructures such as radial gaps and rings in a sample of 24 discs. This study characterises the radial structure of debris discs in the ARKS programme. To identify and quantify the disc substructures, we modelled all discs with a range of non-parametric and parametric approaches. We find that of the 24 discs in the sample, 5 host multiple rings, 7 are single rings that display halos or additional low-amplitude rings, and 12 are single rings with at most tentative evidence of additional substructures. The fractional ring widths that we measured are significantly narrower than previously derived values, and they follow a distribution similar to the fractional widths of individual rings resolved in protoplanetary discs. However, there exists a population of rings in debris discs that are significantly wider than those in protoplanetary discs. We also find that discs with steep inner edges consistent with planet sculpting tend to be found at smaller (<100 au) radii, while more radially extended discs tend to have shallower edges more consistent with collisional evolution. An overwhelming majority of discs have radial profiles well-described by either a double power law or double-Gaussian parametrisation. While our findings suggest that it may be possible for some debris discs to inherit their structures directly from protoplanetary discs, there exists a sizeable population of broad debris discs that cannot be explained in this way. Assuming that the distribution of millimetre dust reflects the distribution of planetesimals, mechanisms that cause rings in protoplanetary discs to migrate or debris discs to broaden soon after formation may be at play, possibly mediated by planetary migration or scattering. - oai:arXiv.org:2601.13670v1 - astro-ph.EP - astro-ph.IM - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.1051/0004-6361/202556450 - Yinuo Han, Elias Mansell, Jeff Jennings, Sebastian Marino, A. Meredith Hughes, Brianna Zawadzki, Anna Fehr, Jamar Kittling, Catherine Hou, Aliya Nurmohamed, Junu Lee, Allan Cheruiyot, Yamani Mpofu, Mark Booth, Richard Booth, Myriam Bonduelle, Aoife Brennan, Carlos del Burgo, John M. Carpenter, Gianni Cataldi, Eugene Chiang, Steve Ertel, Thomas Henning, Marija R. Jankovic, \'Agnes K\'osp\'al, Alexander V. Krivov, Joshua B. Lovell, Patricia Luppe, Meredith A. MacGregor, Sorcha Mac Manamon, Jonathan P. Marshall, Luca Matr\`a, Julien Milli, Attila Mo\'or, Johan Olofsson, Tim Pearce, Sebasti\'an P\'erez, Antranik A. Sefilian, Philipp Weber, David J. Wilner, Mark C. Wyatt - - - Three-dimensional properties of a coronal shock and the longitudinal distribution of its related solar energetic particles - https://arxiv.org/abs/2601.13692 - arXiv:2601.13692v1 Announce Type: new -Abstract: This study aims to investigate the relationship between the spatial-temporal evolution of shock properties and the longitudinal dependence of SEP intensities and spectra. The shock parameters, including the normal speed, oblique angles, compression ratio, and Alfven Mach number, were derived by combining a steady-state solar-wind simulation with the three-dimensional (3D) reconstruction of the shock surface based on multi-view observations. We compared the local shock parameters at the magnetic connecting points with in situ proton intensities and peak spectra to establish the link between shock evolution and SEP characteristics. The shock nose consistently exhibited higher particle-acceleration efficiency with the largest normal speed, compression ratio, and supercritical Alfven Mach number, while the flanks showed delayed transition to supercritical Alfven Mach number with weaker efficiency. The earliest and most rapid proton enhancement of STEREO-B correlated with efficient shock acceleration and prompt magnetic connectivity to the shock. Spectral analysis revealed that proton energy spectra were consistent with the relativistic diffusive shock acceleration (DSA) estimations. The initial shock acceleration began at about 1.4-5 Rsun and caused the widespread longitudinal SEP distribution. The longitudinal dependence of SEP intensity and spectral variations arise from the combined influence of 3D shock properties, magnetic connectivity, and particle transport processes. The agreement between in situ proton indices and relativistic DSA estimations supports DSA in this SEP event and provides insights into the early-stage acceleration at the source region. - oai:arXiv.org:2601.13692v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yue Zhou, Li Feng, Guanglu Shi, Jingnan Guo, Liuguan Ding, Yi Yang, Jianchao Xue, Jun Chen, Weiqun Gan - - - XPE and VLT /FORS2 polarimetry challenge the Seyfert-1.9 classification of MCG-05-23-16 - https://arxiv.org/abs/2601.13701 - arXiv:2601.13701v1 Announce Type: new -Abstract: We report the third observation of the Seyfert-1.9 active galactic nucleus (AGN) MCG-05-23-16 with the Imaging X-ray Polarimetry Explorer (\textit{IXPE}), together with optical spectro-polarimetry obtained at the Very Large Telescope (VLT), and combined with archival near-ultraviolet, optical and near-infrared polarimetric data. No X-ray polarization was detected in the 2-8 keV band, with a 99\% confidence upper limit of $\leq$2.9\%, further reduced to $\leq$2.5\% when combined with the two past IXPE observations of the same target. Monte Carlo simulations suggest that equatorial coronal models are disfavored if the AGN is indeed a type-1.9/2 AGN, but coronae coplanar to the accretion disk remain consistent if the source is less inclined than previously assumed. \textit{VLT}/FORS2 data reveal a typical type-2 spectrum in total flux, a broad H$\alpha$ line in polarized flux, and strongly wavelength dependent polarization degree and angle, rotating by nearly 70$^\circ$ across the optical band. Comparison with historical measurements confirms long-term stability of the polarization spectrum and a $\sim$90$^\circ$ rotation in the near-ultraviolet. Interpreting the multi-wavelength polarization relative to the AGN ionization axis indicates that the main obscurer is not a compact circumnuclear torus, but a distant kpc-scale dust lane crossing the galaxy. This result implies that MCG-05-23-16 is in fact a type-1 AGN seen through foreground dust. The low X-ray column density becomes consistent with the absence of polarization, provided that the nuclear inclination is low. - oai:arXiv.org:2601.13701v1 - astro-ph.HE - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Fr\'ed\'eric Marin, Daniele Tagliacozzo, Francesco Ursini, Damien Hutsem\'ekers, Mitsuru Kokubo, Thibault Barnouin, Andrea Gnarini, Alessandro Leonardo Lai, Jir\'i Svoboda, Stefano Bianchi, Vittoria Elvezia Gianolli, Ephraim Gau, Kun Hu, Henric Krawczynski, W. Peter Maksym, Andrea Marinucci, Herman Marshall, Giorgio Matt, Riccardo Middei, Pierre-Olivier Petrucci, Simonetta Puccetti, Nicole Rodriguez, Roberto Serafinelli, Francesco Tombesi - - - A jet-gas interaction beyond the host galaxy: detection of a neutral hydrogen outflow at cosmic noon - https://arxiv.org/abs/2601.13728 - arXiv:2601.13728v1 Announce Type: new -Abstract: We present upgraded Giant Metrewave Radio Telescope (uGMRT) observations of 0731+438, an \mbox{FR II} radio galaxy at a redshift of 2.429 with two lobes separated by 82 kpc. A blueshifted, faint and broad \mbox{H{\sc i}} 21 cm absorption line with velocity full width at half maximum (FWHM) $\sim 600\,\rm km\,s^{-1}$ is detected against the southern radio lobe that is 47 kpc from radio core, indicating a neutral hydrogen outflow associated with jet-gas interaction beyond the host galaxy. The outflow has a mass outflow rate of $\sim\,0.4T_{\rm s}\Omega\rm\, M_\odot\,{\rm yr}^{-1}$, which could increase to $\sim\,4.0T_{\rm s}\Omega\rm\,M_\odot\,{\rm yr}^{-1}$, corresponding to an energy outflow rate of $2.4T_{\rm s}\Omega\times10^{40}$ -- $1.5T_{\rm s}\Omega\times10^{41}\,\rm erg\,s^{-1}$, where $T_{\rm s}$ is the spin temperature and $\Omega$ is the solid angle of the outflow. Previous optical observations identified an extended emission line region aligned with the radio axis, ionized by the central Active Galactic Nucleus (AGN). Within this region, a warm and ionized outflow with a mass outflow rate of $\sim\,50\rm\, M_\odot\,{\rm yr}^{-1}$ and an energy outflow rate of $\sim1.7\times10^{43}\,\rm erg\,s^{-1}$ was detected. We propose that both the extended emission line region and the optical outflow are results of synergistic effect between jet and AGN radiation. The AGN likely exerts negative feedback on the host galaxy, as evidenced by the gas expulsion by the jet and the high velocity dispersion of ionized gas observed optically. So far, detections of jet-driven neutral hydrogen outflows remain rare. The high redshift, large outflow radii, substantial mass outflow rate and energy outflow rate of the neutral hydrogen outflow in 0731+438 expand the known parameter space of such outflows. - oai:arXiv.org:2601.13728v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Renzhi Su, Stephen J. Curran, James R. Allison, Marcin S{\l}owacki, Minfeng Gu, Vanessa Moss, Yongjun Chen, Zhongzu Wu, Zheng Zheng + Haipeng An, Tingyu Li, Chen Yang - SIRIUS: Dark matter cusp evolution in dense dwarf galaxies - https://arxiv.org/abs/2601.13765 - arXiv:2601.13765v1 Announce Type: new -Abstract: Dwarf galaxies have a wide variety of structures, such as dark matter (DM) distribution, stellar-to-halo mass ratio, and stellar density. Recent high-resolution simulations have shown a variety of stellar-to-halo mass ratios for dwarf galaxies with a DM halo mass of $\sim 10^9 M_{\odot}$ at $z=0$. In this study, we performed cosmological $N$-body/smoothed-particle hydrodynamic zoom-in simulations of dwarf galaxies with the highest gas and DM particle mass resolutions of 2.37 $M_{\odot}$ and 12.8 $M_{\odot}$, respectively. The stellar-to-DM halo mass ratio of one of our simulated dwarf galaxies was $\sim 10^{-4}$, typical for satellites of the Milky Way. The stellar mass ($10^5 M_{\odot}$) and half-mass radius (68 pc) were also similar to those of the satellites of the Milky Way. The power-law slope of the DM halo was $\alpha = -1.1$. On the other hand, the other simulated galaxy exhibited a stellar-to-halo mass ratio of $\sim 10^{-3}$ and a steeper power-law slope ($\alpha=-1.9$) than the other; the presence of baryonic matter deepened the cusp. The mass of $>10^6 M_{\odot}$ and a half-mass radius of $\sim 36$ pc of this galaxy were similar to those of ultra-compact dwarf galaxies rather than the satellites of the Milky Way. This DM halo grew in mass earlier than the former one, and the central DM density was higher than that of the other even in the DM-only simulations. - oai:arXiv.org:2601.13765v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Katsuhiro Kaneko, Takayuki R. Saitoh, Yutaka Hirai, Michiko S. Fujii - - - Still Accelerating: Type Ia supernova cosmology is robust to host galaxy age evolution - https://arxiv.org/abs/2601.13785 - arXiv:2601.13785v1 Announce Type: new -Abstract: Type Ia supernovae are a cornerstone of modern cosmology, providing first evidence for cosmic acceleration and new tests of dark energy. Son et al. 2025 (S25) claim a strong redshift evolution in standardized supernova luminosities driven by supernova progenitor age, with dramatic cosmological implications: rapidly evolving dark energy, decelerating expansion, and a $9\sigma$ tension with $\Lambda$CDM. We show that the underpinning evidence required for this conclusion -- the supernova progenitor-age dependence, the redshift-dependent age difference, and their combined impact -- is either negligible or relies on effects already corrected for in modern supernova analyses. First, the S25 analysis omits the standard host-galaxy stellar mass correction that captures known environmental dependencies that also correlate with stellar age. Applying this correction to the S25 sample, we find no dependence of standardized supernova brightness on host age. Independent data also show no significant difference at low-redshift in standardized brightness between star-forming galaxies and several Gyr older quiescent galaxies of the same stellar mass. Second, the S25 scenario predicts strong redshift evolution of the host-mass effect. Data from the Dark Energy Survey supernova survey measure evolution of $-0.028 \pm 0.034~\mathrm{mag}\,z^{-1}$, consistent with zero and altering the dark-energy equation-of-state measurement ($w$) by $<$0.01 if included. Third, we demonstrate that the claimed $\sim5$~Gyr progenitor age difference between nearby and distant supernovae is overstated by factors of three to five largely due to a conflation of host galaxy age with supernova progenitor age. We conclude that type~Ia supernova cosmology remains robust for current measurements of dark energy. - oai:arXiv.org:2601.13785v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Phil Wiseman, Brodie Popovic, Mark Sullivan, Adam G. Riess, Dan Scolnic, Rebecca C. Chen, Tamara M. Davis, Llu\'is Galbany, Isobel M. Hook, Saurabh W. Jha, Lisa Kelsey, Yukei S. Murakami, Micka\"el Rigault, Benjamin M. Rose, Brian Schmidt, Mat Smith, Maria Vincenzi - - - Tracing Cosmological Signature with Doppler Lensing: Insights from Cosmological Simulations - https://arxiv.org/abs/2601.13820 - arXiv:2601.13820v1 Announce Type: new -Abstract: Doppler lensing, a relativistic effect resulting from the peculiar velocities of galaxies along the line of sight, provides insight into the large-scale structure of the Universe. Relativistic simulations are essential for modeling Doppler lensing because they incorporate gravity and motion in spacetime. We compare two relativistic $N$-body simulation frameworks, $\texttt{GEVOLUTION}$ and $\texttt{SCREENING}$, to calculate Doppler lensing convergence in cosmic voids of different sizes and halos of different masses. Our analysis reveals scale-dependent performance: $\texttt{SCREENING}$ shows larger differences in small voids (radius range: 15--25 Mpc/h) with a mean absolute relative difference of 38.5\%, due to linearized dynamics failing in nonlinear regimes. Medium voids (25--35 Mpc/h) show better agreement (9.5\% mean difference). For large voids (35--45 Mpc/h), $\texttt{SCREENING}$ exhibits intermediate differences (16.9\% mean difference) with central instabilities. Moreover, our Doppler convergence analysis with massive halos ($10^{11.5}$--$10^{14} {~h^{-1}\mathrm{M}_\odot}$) demonstrates excellent consistency (1.6--3.6\% mean difference). These findings provide clear guidance for simulation choice: $\texttt{GEVOLUTION}$ is recommended for precision studies critical to $\Lambda$CDM or modified gravity tests, while $\texttt{SCREENING}$ offers a computationally efficient alternative for relativistic treatments with large catalogs of voids and halos, assisting future astrophysical surveys. - oai:arXiv.org:2601.13820v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Mubtasim Fuad, Sonia Akter Ema, Md Rasel Hossen - - - Examination of frequency and scale dependence of CMB hemispherical power asymmetry - https://arxiv.org/abs/2601.13830 - arXiv:2601.13830v1 Announce Type: new -Abstract: In this study, we revisit the well-known cosmic microwave background (CMB) anomaly referred to as Hemispherical Power Asymmetry (HPA), using CMB temperature maps from the Planck mission public release 4 (PR4) and the WMAP nine-year data release. Employing the Local Variance Estimator (LVE) method, we systematically reexamine the properties of HPA to investigate possible frequency dependence as well as scale dependence in its amplitude and direction. We model the HPA as a scale-dependent dipole modulation following a power-law form, rather than assuming a scale-invariant case. - Our analysis incorporates seven cleaned frequency-specific CMB temperature maps from both the Planck and WMAP missions to test the robustness of the observed asymmetry across instruments and frequency channels. We find that the dipolar modulation characteristic of HPA is present in all cases examined, with consistent estimates of the preferred direction and scale-dependent variation in dipole amplitudes. These results support the conclusion that the observed asymmetry is unlikely to arise from instrumental artifacts or data-processing effects, and instead points toward a persistent large-scale feature of the CMB sky with a possible cosmological origin. - oai:arXiv.org:2601.13830v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sanjeev Sanyal, Pavan Kumar Aluri, Arman Shafieloo - - - Follow-up of three exocomet-host candidates - https://arxiv.org/abs/2601.13850 - arXiv:2601.13850v1 Announce Type: new -Abstract: Exocomets are small bodies that evaporate when they approach their host star. They are detected through variability of non-photospheric features with spectroscopy and/or asymmetric transits in time-series photometry. In the past four decades ~30 systems have shown such variations, and were therefore classified as exocomet host stars. However, some publications have pointed out mechanisms that might mimic exocometary features, and therefore, careful monitoring is needed to confirm the origin of the observed variability. With this paper we aim to investigate the exocomet nature of the non-photospheric variable features observed in the exocomet candidate stars HD 36546, HD 42111 and HD 85905. All of them have shown some degree of variability, particularly in their Ca II K line. We analysed the non-photospheric Ca II K line features from high-resolution spectra obtained using new NOT/FIES and Mercator/HERMES, and some additional archival spectra of the target stars. The variability was quantified through the changes in the equivalent widths of those features, which are assumed to be of circumstellar origin. Column densities were also estimated for each variable feature. Strong variability was found for HD 85905, consistent with a potential link to exocometary activity. However, the binarity of the system, which we confirmed through interferometric VLTI/PIONIER observations, complicates the interpretation of these signatures and prevents us from drawing definitive conclusions. The remaining two sources do not show any significant variability, but due to the sporadic nature of the exocometary events, we cannot discard the exocomet hypothesis. Further monitoring of the stars will be necessary to carry out a robust determination of the variability patterns and timescales that would completely rule out other scenarios. - oai:arXiv.org:2601.13850v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - P. Mu\~noz-Cutanda, I. Rebollido, B. Montesinos, P. Cruz, O. Absil, S. Ertel - - - The Characteristic Mass and Energy Conversion Efficiency in the Cusp-Core Transition of Dark Matter Haloes: Implications for Scaling Relations and Supernova feedbacks - https://arxiv.org/abs/2601.13868 - arXiv:2601.13868v1 Announce Type: new -Abstract: Galaxies in the nearby Universe, particularly dwarf systems, exhibit inner mass profiles of dark matter haloes that systematically depart from canonical cold dark matter expectations, signalling an interplay between baryonic feedback and the collisionless halo. We update an analytical cusp-core transition model by incorporating the effect of supernova-driven mass loss. Adapting this model to SPARC galaxies, we measure the energy conversion efficiency epsilon, defined as the fraction of supernova feedback energy that is used to change the central dark-matter potential. We find epsilon ~ 0.01 for nearby SPARC galaxies. Building on these measurements, we compare the dynamical energy required for a cusp-core transformation with the feedback energy available over burst cycles and identify a cusp-core transition forbidden region on the halo-stellar mass plane where transformation cannot occur. Galaxies with halo masses from 10^8 to 10^11 M_sun lie outside the forbidden region, whereas ultra-faint dwarf galaxies < 10^8 M_sun, galaxy groups and clusters > 10^11 M_sun fall within it, consistent with their high central densities and the inefficiency of core formation at very low and very high masses. This approach also explains the observed diversity of inner density profiles in low-mass systems, showing that both the star formation rate and the energy conversion efficiency govern them, with the latter emerging as a key parameter setting the strength of the cusp-core transition. Beyond the cusp-core problem, our observationally inferred energy conversion efficiency provides a model independent benchmark that strongly constrains galaxy formation models. - oai:arXiv.org:2601.13868v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Michi Shinozaki, Masao Mori, Yuka Kaneda, Kohei Hayashi - - - Boxy/Peanut Bulges: Comparative Analysis of EGIPS Galaxies and TNG50 Models - https://arxiv.org/abs/2601.13893 - arXiv:2601.13893v1 Announce Type: new -Abstract: We investigated the properties of boxy/peanut-shaped (B/PS) bulges in a sample of 71 galaxies from the Edge-on Galaxies in the Pan-STARRS Survey (EGIPS) and 20 simulated galaxies from Illustris TNG50 using multicomponent photometric decomposition. For each real and simulated galaxy, we obtained a suitable photometric model in which the B/PS bulge was represented by a dedicated 2D photometric function. For real galaxies, we found that more flattened X-structures are generally residing in larger B/PS bulges. When tested against the galaxy masses, we verified that both larger bulges and more flattened X-structures are typically found in more massive galaxies. Since large bars are also known to reside in more massive galaxies, we conclude that the flatness of X-structures in larger B/PS bulges has a physical origin, rather than being solely a result of projection effects due to differences in observed bar viewing angles. When comparing the properties of B/PS bulges between EGIPS galaxies and TNG50 galaxies, with bars rotated for different viewing angles, we found that B/PS bulges in TNG50 are considerably smaller and less luminous in terms of total intensity. This is consistent with previous studies of bar properties in TNG50, indicating the B/PS bulges in TNG50 differ from those in real galaxies, as do their parent bars. - oai:arXiv.org:2601.13893v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3390/galaxies14010004 - https://www.mdpi.com/2075-4434/14/1/4 - Anton Smirnov, Alexander Marchuk, Viktor Zozulia, Natalia Sotnikova, Sergey Savchenko - - - Prospecting MeerKAT Continuum Data for Enigmatic Radio Sources with Unsupervised Vector-Quantised Variational Autoencoders - https://arxiv.org/abs/2601.13901 - arXiv:2601.13901v1 Announce Type: new -Abstract: We present a novel application of Vector quantised variational autoencoders (VQ-VAEs) to deep 1.28 GHz radio continuum images taken from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS).VQ-VAEs are deep learning models widely used in modern computer vision applications and pipelines. Designed for image generation, VQ-VAEs are trained to reconstruct the input dataset via a low-dimensional discrete embedding. VQ-VAEs effectively learn the distribution of training data, where samples that do not fit the distribution well yield the highest reconstruction errors. This property makes VQ-VAEs a good candidate for the task of anomaly detection. In this work, we examine the effectiveness of VQ-VAEs in identifying radio continuum sources with anomalous structures in the image-plane domain. We find VQ-VAEs to be useful as part of a solution for searching such large datasets. We observe that they are able to remove a majority of the typical sources in such data, even when trained in an unsupervised manner on unlabelled data. We also provide our testing set of a large sample of manually labelled radio sources, in particular radio galaxies, taken from the MGCLS at 1.28 GHz. Automated approaches to searching through high volumes of data are key in extracting the full scientific potential of the Square Kilometre Array and its pathfinders. - oai:arXiv.org:2601.13901v1 - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Fernando L. Ventura, Kshitij Thorat, Anna Bosman, Roger Deane, Christopher Cleghorn - - - Frequency shift and viewing direction variations in gravitational lensing - https://arxiv.org/abs/2601.13912 - arXiv:2601.13912v1 Announce Type: new -Abstract: In a gravitational lensing system, the relative transverse velocities of the lens, source, and observer induce a frequency shift in the observed radiation. While this shift is typically negligible in most astrophysical contexts, strategies for its detection have been proposed for both electromagnetic and gravitational waves. This paper provides a rigorous theoretical treatment of the effect, deriving general expressions for the frequency shift within a lensing system embedded in a cosmological spacetime. Our formulation remains valid for arbitrary distances and velocities - including highly relativistic regimes - under any Friedmann-Lema\^itre-Robertson-Walker metric. - Expanding upon previous papers on moving lenses, we provide a detailed analysis of frequency effects induced by lenses moving at relativistic speeds. Furthermore, we extend standard lensing theory by deriving an exact formula for the variation in the source's viewing direction. This result is of interest for strongly anisotropic emitters, such as compact binary systems emitting gravitational waves. Finally, we quantify the apparent misalignment between the lens and the source's two images produced by time-delay effects in lens systems moving with high velocity. - oai:arXiv.org:2601.13912v1 - astro-ph.CO - astro-ph.GA - gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Miko{\l}aj Korzy\'nski, Mateusz Kulejewski - - - Primitive asteroids in the main belt, Cybele, and Hilda populations from Gaia DR3 - https://arxiv.org/abs/2601.13925 - arXiv:2601.13925v1 Announce Type: new -Abstract: Primitive asteroids include C-, P-, and D-classes, known to be dark and having spectra mostly featureless. They differ in the spectral slope, which ranges from moderate values for C-types, and progressively increases in P- and D-types, the latter being the reddest. While C- and P-types are commonly observed in the asteroid main belt, D-types are commonly found further from the Sun, in the Cybele, Hilda, and Jupiter Trojans regions, and very few are reported in the main belt. This study aims at characterizing the abundance of primordial and red asteroids, belonging to the P-, D-, and Z-classes in the Mahlke et al. (2022) taxonomy, in the 2-5.2 AU region using the third data release by the Gaia mission spectral catalog, which includes more than 60000 spectrophotometric data of asteroids. We have applied the following methodology to identify primordial asteroids in the catalog: 1) selection of objects with signal to noise ratio greater than 20; 2) albedo value less than 12%; 3) chi-squared fit to automatically identify potential D-, Z-, and P-types using Bus-DeMeo and Mahlke taxonomy; 4) visual inspection of every spectrum to confirm the taxonomic classification. Referring to Mahlke taxonomy, we have found 318 new D-types across the main belt, as well as 124 Z-types, and is in agreement with theoretical estimations. We computed the spectral slope in the visible range (0.55 - 0.81 \mu m). We also have identified 265 P-types in the main belt. For the Cybele and Hilda asteroids, we characterize the taxonomic class of all the bodies with SNR higher than 20 in the Gaia catalog, for a total sample of 193 and 180 asteroids, respectively. - oai:arXiv.org:2601.13925v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Noemie El-Bez-Sebastien, Sonia Fornasier, Antoine Seurat, Antonin Wargnier - - - Secular Evolution of PSR J2021+4026: Long-Term {\gamma}-Ray Flux and Spin-Down Variability Beyond State Transitions - https://arxiv.org/abs/2601.13940 - arXiv:2601.13940v1 Announce Type: new -Abstract: PSR J2021+4026 is a remarkable $\gamma$-ray pulsar exhibiting repeated transitions between high $\gamma$-ray flux (HGF) and low $\gamma$-ray flux (LGF) states. With 17-yr Fermi-LAT monitoring, we reveal persistent secular evolution and enhanced spin-down rate variability within individual emission states -- beneath the quasi-periodic state transitions. After removing discrete jumps, the jump-corrected flux $\delta F_\gamma$ shows a three-phase evolution: rise ($+2.02^{+0.17}_{-0.15}\%~\mathrm{yr}^{-1}$), decline ($-3.72^{+0.34}_{-0.47}\%~\mathrm{yr}^{-1}$), and rapid rise ($+14.9^{+6.4}_{-4.4}\%~\mathrm{yr}^{-1}$), with all rates quoted relative to the long-term mean flux $\langle F_\gamma \rangle=7.8\times 10^{-10}\,\mathrm{erg}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$. Moreover, the flux of the LGF state is gradually approaching the stable HGF level at a rate of $+0.72 \pm 0.11\%~\mathrm{yr}^{-1}$. These results demonstrate that secular flux evolution in PSR J2021+4026 operates largely independently of discrete state transitions, yet jointly with them drives the system toward a stable high-flux equilibrium. - oai:arXiv.org:2601.13940v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xue-Zhi Liu, Ming-Yu Ge, Xiao-Ping Zheng, Xiao-Bo Li, Han-Long Peng, Wen-Tao Ye, Bo-Yan Chen, Shi-Jie Zheng, Fang-Jun Lu, Shuang-Nan Zhang - - - Rotational enhancement and stability of protoquark stars during thermal evolution - https://arxiv.org/abs/2601.13941 - arXiv:2601.13941v1 Announce Type: new -Abstract: We present the first systematic study of rigidly rotating protoquark stars based on isentropic equations of state (EOS) within the density-dependent quark mass (DDQM) framework. Using a quasi-static equilibrium approach, we follow the Kelvin--Helmholtz evolution from hot, lepton-rich matter to a cold, catalyzed quark star. Rotation substantially enhances the maximum stable mass (by up to $\sim 40\%$), equatorial radius, and key rotational observables, with the ratio of rotational kinetic to gravitational potential energy, $T_{\rm kin}/|W|$, reaching $0.18$--$0.19$ near the Keplerian limit, indicating a heightened susceptibility to gravitational-wave--emitting instabilities. Thermal evolution introduces a clear ordering: all stellar properties peak during the lepton-rich stages and decrease monotonically as the star cools. Compared to hadronic stars, rotating protoquark stars exhibit larger radii, higher moments of inertia, and stronger quadrupolar deformation, producing a distinct signature in the mass--radius--spin plane that can accommodate objects such as HESS~J1731--347 and PSR~J0740+6620. These results demonstrate that future multimessenger observations must account for both thermal history and rotation to robustly identify quark matter in compact stars. - oai:arXiv.org:2601.13941v1 - astro-ph.HE - hep-ph - nucl-th - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Adamu Issifu, Andreas Konstantinou, Prashant Thakur, Tobias Frederico - - - Optimising gravitational-wave sky maps for pulsar timing arrays - https://arxiv.org/abs/2601.13957 - arXiv:2601.13957v1 Announce Type: new -Abstract: Pulsar timing arrays (PTAs) have recently reported compelling evidence for the presence of a gravitational-wave background signal. Mapping the gravitational-wave background is key to understanding how it is formed, since anisotropy is a tracer for, for example, a supermassive black hole binary origin. In this work we refine the frequentist regularised gravitational-wave mapping analysis developed in our previous work (as part of the MeerKAT PTA 4.5-year data release). We derive a point-spread function describing the angular resolution of a PTA. We investigate how the point spread function changes for different PTA constellations and determine the best possible angular resolution achievable within our framework. Using simulated data, we demonstrate that previous methods do not capture the actual resolution - especially in regions of the sky with a high density of pulsars. We propose an improved scheme that accounts for a variable local resolution and test it using realistic simulations of the latest MeerKAT dataset. We demonstrate that we are able to identify a continuous gravitational wave signal in a region with good pulsar sky coverage with approximately a factor of two increase in significance compared to our previous method. - oai:arXiv.org:2601.13957v1 - astro-ph.IM - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Kathrin Grunthal, David J. Champion, Eric Thrane, Rowina S. Nathan, Michael Kramer, Matthew T. Miles - - - X-ray Analysis and Photon-transport Simulations of SMC X-1: A Warped-disc Origin of the Superorbital Modulation - https://arxiv.org/abs/2601.13978 - arXiv:2601.13978v1 Announce Type: new -Abstract: The luminous accreting pulsar SMC X-1 is an appropriate target to explore the accretion dynamics. SMC X-1 shows unique quasi-periodic flux variability of 40-65$\,$days known as superorbital modulation. To constrain the accretion structure of SMC X-1 based on timing and spectral study, we have analysed X-ray data of SMC X-1 observed by Suzaku and NuSTAR at various epochs between 2011 and 2022. The spectral analysis shows that the hydrogen column density ($N_\mathrm{H}$) increases from $1.1 \times 10^{22}\,\mathrm{cm^{-2}}$ to $1.24 \times 10^{23}\,\mathrm{cm^{-2}}$ as the flux decreases with the superorbital modulation. The neutral iron K$\alpha$ line at 6.4$\,$keV has a broad width of 0.3$\,$keV, and its equivalent width increases as toward superorbital low states. The line broadening is consistent with Keplerian motion at the inner disc rather than the stellar wind velocity of the donor star. These findings support that the superorbital modulation is a consequence of X-ray attenuation by the warped accretion disc. To test this interpretation, we have conducted photon transport simulations of a system consisting of a neutron star, a warped disc, and optically-thin disc atmosphere. Occultation of the central source by the disc successfully reproduces the observed variations in the equivalent width of neutral iron K$\alpha$ line, pulse profiles, and flux in hard X-rays. Notably, a disc precession angle of approximately $30^\circ$ can account for the observational features. For the radiation pattern of the photon source, the preferred beam width corresponds to a standard deviation of $30^\circ$. - oai:arXiv.org:2601.13978v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Satoshi Takashima, Hirokazu Odaka, Ryota Tomaru, Atsushi Tanimoto, Aya Bamba, Toru Tamagawa - - - Evaluating state-of-the-art cloud quantum computers for quantum neural networks in gravitational waves data analysis - https://arxiv.org/abs/2601.14036 - arXiv:2601.14036v1 Announce Type: new -Abstract: In this work, we explore the possibility of using quantum computers provided for usage in cloud by big companies (such as IBM, IonQ, IQM Quantum Computers, etc.) to run our quantum neural network (QNN) developed for data analysis in the context of LISA Space Mission, developed with the Qiskit library in Python. Our previous work demonstrated that our QNN learns patterns in gravitational wave (GW) data much faster than a classical neural network, making it suitable for fast GW signal detection in future LISA data streams. Analyzing the fees from hardware providers like IBM Quantum, Amazon Braket and Microsoft Azure, we found that the fees for running the first segment of our QNN sum up to \$2000, \$60000, and \$1000000 respectively. Using free plans, we succeed to run the 3-qubit feature map of the QNN for one random data sample on {\fontfamily{qcr} \selectfont ibm\_kyoto} and {\fontfamily{qcr}\selectfont IQM Quantum Computers\_Garnet} quantum computers, obtaining a fidelity of 99\%; we could also run the first prediction segment of our QNN on {\fontfamily{qcr} \selectfont ibm\_kyoto}, implemented for 4 qubits, and obtained a prediction accuracy of 20\%. We queried providers such as IBM Quantum, Amazon Braket, Pasqal, and Munich Quantum Valley to obtain access to their plans, but, with the exception of Amazon Braket, our applications remain unanswered to this day. Other major setbacks in using the quantum computers we had access to included Qiskit library version issues (as in the cases of IBM Quantum and IQM Quantum Computers) and the frequent unavailability of the devices, as was the case with the Microsoft Azure provider. All the results presented in this paper were accumulated in 2024. - oai:arXiv.org:2601.14036v1 - astro-ph.CO - astro-ph.IM - physics.data-an - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Maria-Catalina Isfan, Laurentiu-Ioan Caramete, Ana Caramete - - - Discovery and characterisation of two exoplanets orbiting the metal-poor, solar-type star TOI-5788 with TESS, CHEOPS, and HARPS-N - https://arxiv.org/abs/2601.14045 - arXiv:2601.14045v1 Announce Type: new -Abstract: We present the discovery and characterisation of two transiting exoplanets orbiting the metal-poor, solar-type star TOI-5788. From our analysis of six \textit{TESS} sectors and a dedicated \textit{CHEOPS} programme, we identify an inner planet (TOI-5788~b; $P = 6.340758\pm0.000030\,\si{\day}$) with radius $1.528\pm0.075\,\mathrm{R_\oplus}$ and an outer planet (TOI-5788~c; $P = 16.213362\pm0.000026\,\si{\day}$) with radius $2.272\pm0.039\,\mathrm{R_\oplus}$. We obtained 125 radial-velocity spectra from HARPS-N and constrain the masses of TOI-5788~b and~c as $3.72\pm0.94\,\mathrm{M_\oplus}$ and $6.4\pm1.2\,\mathrm{M_\oplus}$, respectively. Although dynamical analyses indicate that a third planet could exist in a stable orbit between 8 and 14 days, we find no evidence of additional planets. Since the TOI-5788 system is one of the few systems with planets straddling the radius gap, and noting that there are even fewer such systems around metal poor stars, it is a promising system to constrain planet formation theories. We therefore model the interior structures of both planets. We find that TOI-5788~b is consistent with being a rocky planet with almost no envelope, or having an atmosphere of a high mean molecular weight. We find that TOI-5788~c is consistent with both gas-dwarf and water-world hypotheses of mini-Neptune formation. We model the atmospheric evolution history of both planets. Whilst both scenarios are consistent with the atmospheric evolution of TOI-5788~c, the gas-dwarf model is marginally preferred. The results of the atmospheric evolution analysis are not strongly dependent on stellar evolution. This makes the system a promising target to test internal structure and atmospheric evolution models. - oai:arXiv.org:2601.14045v1 - astro-ph.EP - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Ben S. Lakeland, A. Mortier, R. D. Haywood, S. Ulmer-Moll, Z. Garai, A. Vanderburg, J A. Egger, D. A. Turner, D. Kubyshkina, A. C. M. Correia, H. P. Osborn, L. A. Buchhave, L. Malavolta, A. Bonfanti, W. Boschin, A. Cameron, A. Castro-Gonz\'alez, R. Cosentino, M. Damasso, X. Dumusque, D. Ehrenreich, Z. Essack, S. Filomeno, L. Fossati, D. Gandolfi, M. Gillon, C. Hedges, M. L\'opez-Morales, G. Lacedelli, M. Lendl, J. Maldonado, G. Mantovan, A. F. Mart\'inez Fiorenzano, P. F. L. Maxted, C. Mordasini, B. Nicholson, S. M. O'Brien, L. Palethorpe, E. Palle, M. Pinamonti, D. Rapetti, I. Ribas, N. C. Santos, A. M. Silva, A. Sozzetti, M. Stalport, G. Szab\'o, S. Udry, M. Vezie, C. A. Watson, T. G. Wilson - - - Unveiling Hidden Clustering: An Unsupervised Machine Learning Study of Repeating FRB 20220912A - https://arxiv.org/abs/2601.14065 - arXiv:2601.14065v1 Announce Type: new -Abstract: Fast Radio Bursts (FRBs) are millisecond-duration radio transients of extragalactic origin. Classifying repeating FRBs is essential for understanding their emission mechanisms, but remains challenging due to their short durations, high variability, and increasing data volume. Traditional methods often rely on subjective criteria and struggle with high-dimensional data. In this study, we apply an unsupervised machine learning framework that combines Uniform Manifold Approximation and Projection (UMAP) and Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) to eight observed parameters from FRB 20220912A. Our analysis reveals three distinct clusters of bursts with varying spectral and fluence properties. Comparisons with clustering studies on other repeaters show that some of our clusters share similar features with sources such as FRB 20201124A and FRB 121102, suggesting possible common emission mechanisms. We also provide qualitative interpretations for each cluster, highlighting the spectral diversity within a single source. Notably, one cluster shows broadband emission and high fluence, which are typically seen in non-repeating FRBs. This raises the possibility that some non-repeaters may be misclassified repeaters due to observational limitations. Our results demonstrate the utility of machine learning in uncovering intrinsic diversity in FRB emission and provide a foundation for future classification studies. - oai:arXiv.org:2601.14065v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - An-Chieh Hsu, Tetsuya Hashimoto, Tomotsugu Goto, Tomoki Wada, Bjorn Jasper Raquel - - - RV$\times$TESS I: Modeling Asteroseismic Signals with Simultaneous Photometry and RVs - https://arxiv.org/abs/2601.14076 - arXiv:2601.14076v1 Announce Type: new -Abstract: Detecting small planets via the radial velocity method remains challenged by signals induced by stellar variability, versus the effects of the planet(s). Here, we explore using Gaussian Process (GP) regression with Transiting Exoplanet Survey Satellite (TESS) photometry in modeling radial velocities (RVs) to help to mitigate stellar jitter from oscillations and granulation for exoplanet detection. We applied GP regression to simultaneous TESS photometric and RV data of HD 5562, a G-type subgiant ($M_\star=1.09M_{\odot}$, $R_\star=1.88R_{\odot}$) with a V magnitude of 7.17, using photometry to inform the priors for RV fitting. The RV data is obtained by the Magellan Planet Finder Spectrograph (PFS). The photometry-informed GP regression reduced the RV scatter of HD~5562 from 2.03 to 0.51 m/s. We performed injection and recovery tests to evaluate the potential of GPs for discovering small exoplanets around evolved stars, which demonstrate that the GP provides comparable noise reduction to the binning method. We also found that the necessity of photometric data depends on the quality of the RV dataset. For long baseline and high-cadence RV observations, GP regression can effectively mitigate stellar jitter without photometric data. However, for intermittent RV observations, incorporating photometric data improves GP fitting and enhances detection capabilities. - oai:arXiv.org:2601.14076v1 - astro-ph.EP - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jiaxin Tang, Sharon X. Wang, Yaguang Li, Timothy R. Bedding, Guang-Yao Xiao, Fabo Feng, Jie Yu, Zun Wang, Jennifer A. Burt, R. Paul Butler, Brad Carter, Jeffrey D. Crane, Mat\'ias R. D\'iaz, Samuel K. Grunblatt, Daniel Huber, Hugh R. A. Jones, Stephen R. Kane, Jacob K. Luhn, Stephen A. Shectman, Johanna Teske, Rob Wittenmyer, Jason T. Wright, Jeremy Bailey, Simon J. O'Toole, Chris G. Tinney - - - The JEM-EUSO Collaboration: Contributions to the 39th International Cosmic Ray Conference (ICRC2025) - https://arxiv.org/abs/2601.14107 - arXiv:2601.14107v1 Announce Type: new -Abstract: This is a collection of papers presented by the JEM-EUSO Collaboration at the 39th International Cosmic Ray Conference (ICRC 2025) (Geneva, Switzerland, July 14--24, 2025). - oai:arXiv.org:2601.14107v1 - astro-ph.HE - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - M. Abdullahi, M. Abrate, J. H. Adams Jr., D. Allard, P. Alldredge, R. Aloisio, R. Ammendola, A. Anastasio, L. Anchordoqui, V. Andreoli, A. Anzalone, E. Arnone, D. Badoni, P. von Ballmoos, B. Baret, D. Barghini, M. Battisti, R. Bellotti, A. A. Belov, M. Bertaina, M. Betts, P. Biermann, F. Bisconti, S. Blin-Bondil, M. Boezio, A. N. Bowaire, I. Buckland, L. Burmistrov, J. Burton-Heibges, F. Cafagna, D. Campana, F. Capel, J. Caraca, R. Caruso, M. Casolino, C. Cassardo, A. Castellina, K. \v{C}ern\'y, L. Conti, A. G. Coretti, R. Cremonini, A. Creusot, A. Cummings, S. Davarpanah, C. De Santis, C. de la Taille, A. Di Giovanni, A. Di Salvo, T. Ebisuzaki, J. Eser, F. Fenu, S. Ferrarese, G. Filippatos, W. W. Finch, C. Fornaro, C. Fuglesang, P. Galvez Molina, S. Garbolino, D. Garg, D. Gardiol, G. K. Garipov, A. Golzio, C. Gu\'epin, A. Haungs, T. Heibges, F. Isgr\`o, R. Iuppa, E. G. Judd, F. Kajino, L. Kupari, S. -W. Kim, P. A. Klimov, I. Kreykenbohm, J. F. Krizmanic, J. Lesrel, F. Liberatori, H. P. Lima, E. M'sihid, D. Mand\'at, M. Manfrin, A. Marcelli, L. Marcelli, W. Marsza{\l}, G. Masciantonio, V. Masone, J. N. Matthews, E. Mayotte, A. Meli, M. Mese, S. S. Meyer, M. Mignone, M. Miller, H. Miyamoto, T. Montaruli, J. Moses, R. Munini, C. Nathan, A. Neronov, R. Nicolaidis, T. Nonaka, M. Mongelli, A. Novikov, F. Nozzoli, T. Ogawa, S. Ogio, H. Ohmori, A. V. Olinto, Y. Onel, G. Osteria, B. Panico, E. Parizot, G. Passeggio, T. Paul, M. Pech, K. Penalo Castillo, F. Perfetto, L. Perrone, C. Petta, P. Picozza, L. W. Piotrowski, Z. Plebaniak, G. Pr\'ev\^ot, M. Przybylak, H. Qureshi, E. Reali, M. H. Reno, F. Reynaud, E. Ricci, M. Ricci, A. Rivetti, G. Sacc\`a, R. E. Saraev, H. Sagawa, O. Saprykin, F. Sarazin, R. E. Saraev, P. Schov\'anek, V. Scotti, S. A. Sharakin, V. Scherini, H. Schieler, K. Shinozaki, F. Schr\"oder, A. Sotgiu, R. Sparvoli, B. Stillwell, J. Szabelski, M. Takeda, Y. Takizawa, S. B. Thomas, R. A. Torres Saavedra, R. Triggiani, D. A. Trofimov, M. Unger, T. M. Venters, M. Venugopal, C. Vigorito, M. Vr\'abel, S. Wada, D. Washington, A. Weindl, L. Wiencke, J. Wilms, S. Wissel, I. V. Yashin, M. Yu. Zotov, P. Zuccon - - - Accretion flow around Kerr metric in the infra-red limit of asymptotically safe gravity - https://arxiv.org/abs/2601.14113 - arXiv:2601.14113v1 Announce Type: new -Abstract: We investigate accretion disk dynamics and the formation of quasi-periodic oscillations (QPOs) in the infrared limit around Kerr-like black holes in asymptotically safe gravity. Relativistic hydrodynamic solutions of Bondi-Hoyle-Lyttleton (BHL) accretion reveal that quantum corrections significantly modify the structure of the shock cone formed around the black hole. The black hole spin controls the asymmetric of the shock cone through frame-dragging effects, whereas the quantum correction parameter softens the effective gravitational potential, resulting in a wider shock opening angle, weaker post-shock compression, and reduced density concentration within the cone. Time-dependent mass accretion rates reveal oscillation modes trapped within the shock cone. The power spectral density (PSD) investigations suggest that these modes naturally generate low-frequency QPOs, whose amplitudes, coherence, and harmonic structure depend on both the spin and the quantum correction parameter. The PSD analyses performed at different radial locations reveal that identical QPO frequencies are obtained in all cases. The numerically detected frequencies result from the excitation of global oscillation modes trapped within the post-shock region. The resulting global modes are found to consist of fundamental frequencies, their associated harmonic overtones, and near-commensurate frequency ratios such as 2:1 and 3:2. Coherent oscillations are enhanced and near-commensurate frequency ratios are produced when moderate rotation and moderate quantum corrections are coupled. Large quantum correction parameters, on the other hand, wash out unique spectral peaks and suppress oscillation amplitudes. - oai:arXiv.org:2601.14113v1 - astro-ph.HE - gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Orhan Donmez, Sushant G. Ghosh, M. Yousaf, G. Mustafa, Farruh Atamurotov - - - Minutes-long soft X-ray prompt emission from a compact object merger - https://arxiv.org/abs/2601.14137 - arXiv:2601.14137v1 Announce Type: new -Abstract: Compact object mergers are multi-messenger sources and progenitors of some gamma-ray bursts (GRBs), primarily understood by gamma-ray observations, while poorly constrained in the prompt low-energy phase. A long-lasting X-ray emission was discussed as afterglows following several short-duration ($\lesssim$2 s) bursts, yet this prompt X-ray component was not directly observed or confirmed. Here we report the discovery of a minutes-long ($\sim$560 s) flash of soft X-rays immediately following the short ($\sim$0.4 s) GRB 250704B. The long-soft bump points to a distinct phase of prompt emission in X-rays detected by Einstein Probe in an event that otherwise appear as an ordinary short GRB, showing that long-lasting X-ray emission is likely a common feature of merger-driven bursts and a promising electromagnetic counterpart to gravitational-wave sources. - oai:arXiv.org:2601.14137v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - An Li, Chen-Wei Wang, Niccol\`o Passaleva, Jie An, Bin-Bin Zhang, Eleonora Troja, Yi-Han Iris Yin, Yuan Liu, Shao-Lin Xiong, Li-Ping Xin, Yi-Xuan Shao, Jun Yang, Hui Sun, Dong Xu, Yu-Han Yang, Roberto Ricci, He Gao, Sarah Antier, Rosa L. Becerra, Jia-Xin Cao, Alberto Javier Castro-Tirado, Xin-Lei Chen, Ye-Hao Cheng, Yong Chen, Hua-Qing Cheng, Valerio D'Elia, Massimiliano De Pasquale, Yong-Wei Dong, Eslam Elhosseiny, Rob A. J. Eyles-Ferris, Maria Gritsevich, Xu-Hui Han, Dieter Hartmann, You-Dong Hu, Jing-Wei Hu, Shu-Mei Jia, Nino Kochiashvili, Wei-Hua Lei, Andrew J. Levan, Cheng-Kui Li, Dong-Yue Li, Hua-Li Li, Xiao-Bo Li, Zhi-Xing Ling, He-Yang Liu, Hou-Jun Lv, Daniele B. Malesani, Brendan O'Connor, Hai-Wu Pan, Shashi Bhushan Pandey, Ignacio Perez-Garcia, Dani\"elle L. A. Pieterse, Marion Pillas, Yu-Lei Qiu, Andrea Saccardi, Rub\'en S\'anchez-Ram\'irez, Wen-Jun Tan, Manasanun Tanasan, Nial R. Tanvir, Susanna D. Vergani, Jing Wang, Xiao-Feng Wang, Qin-Yu Wu, Shu-Xu Yi, Tillayev Yusufjon, Chen Zhang, Wen-Da Zhang, Yi-Jia Zhang, Guo-Ying Zhao, Chao Zheng, Shi-Jie Zheng, Chang Zhou, Ping Zhou, Bertrand Cordier, Jian-Yan Wei, Weimin Yuan, Shuang-Nan Zhang, Bing Zhang - - - A multi-wavelength study of the 2025 low state of the intermediate polar BG CMi - https://arxiv.org/abs/2601.14156 - arXiv:2601.14156v1 Announce Type: new -Abstract: We present multi-wavelength observations of the first recorded low state of the intermediate polar BG CMi. Optical monitoring of the source by members of the American Association of Variable Star Observers reveals a decrease of ~0.5 mag that lasted ~50 d in early 2025. During the low state the optical timing properties imply that BG CMi underwent a change in the accretion mode, as power at the spin frequency $\omega$ dramatically dropped. An XMM-Newton observation revealed a substantial decrease in intrinsic absorption and a slight increase in intrinsic X-ray luminosity, compared to archival Suzaku data. Timing analysis of the X-ray light curves shows that power shifted from the orbital frequency $\Omega$ (prominent in Suzaku data) to $2\Omega$ in the low state XMM-Newton data, along with the strengthening of certain orbital sidebands. We suggest that BG CMi transitioned to disk-overflow accretion, where the white dwarf accreted matter via both a disk and a stream, the latter becoming more dominant during the low state due to a decrease in the mass and size of the disk. - oai:arXiv.org:2601.14156v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - A. W. Shaw, K. Mukai, C. O. Heinke, C. G. Nixon, D. A. H. Buckley, P. A. Dubovsk\'y, F. -J. Hambsch, J. Hilburn, K. Petr\'ik, R. M. Plotkin, S. B. Potter, N. Rawat, T. Shahbaz, Sharif. Dufoer, S. Dvorak, D. Messier, G. Myers, P. Nelson, R. Sabo, J. Ulowetz, T. Vanmunster - - - Pre-computed aerosol extinction, scattering and asymmetry grids for scalable atmospheric retrievals - https://arxiv.org/abs/2601.14177 - arXiv:2601.14177v1 Announce Type: new -Abstract: The unprecedented wavelength coverage and sensitivity of the James Webb Space Telescope (JWST) permits to measure the absorption features of a wide range of condensate species from Silicates to Titan tholins. Atmospheric retrievals are uniquely suited to analyse these datasets and characterize the aerosols present in exoplanet atmospheres. However, including the optical properties of condensed particles within retrieval frameworks remains computationally expensive, limiting our ability to fully exploit JWST observations. In this work, we improve the computational efficiency and scaling behavior of aerosol models in atmospheric retrievals, enabling in-depth studies including multiple condensate species within practical time scales. Rather than computing the aerosol Mie coefficients for each sampled model, we pre-compute extinction efficiency (Qext), scattering efficiency (Qscat) and asymmetry parameter (g) grids for seven condensate species relevant in exoplanet atmospheres (Mg2SiO4 amorph sol - gel, MgSiO3 amorph glass, MgSiO3 amorph sol - gel, SiO2 alpha, SiO2 amorph, SiO and Titan tholins). The pre-computed Qext grids significantly reduce computation time between 1.4 and 17 times with negligible differences on the retrieved parameters. They also scale effortlessly with the number of aerosol species while maintaining the accuracy of cloud models. Thereby enabling more complex retrievals as well as broader population studies without increasing the overall error budget. The Qext, Qscat and g grids are freely available on Zenodo as well as a public TauREx plugin -TauREx-PCQ- that utilize them. - oai:arXiv.org:2601.14177v1 - astro-ph.EP - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Ma\"el M. Voyer, Quentin Changeat - - - Dynamical mass of a solar-like oscillator at the main-sequence turnoff from Gaia astrometry & ground-based spectroscopy - https://arxiv.org/abs/2601.14197 - arXiv:2601.14197v1 Announce Type: new -Abstract: Asteroseismology is widely used for precise determining of masses of solar-like oscillating stars by performing individual-frequency modeling or applying homological scaling relations. However, these methods lack dynamical validation on the main sequence due to the absence of eclipsing double-lined binary system (SB2) as benchmark objects. By providing the orbital inclination, astrometric binary systems from ESA Gaia DR3 offer an abundant alternative for eclipsing systems. We present KIC693187 as the first SB2, hosting a solar-like oscillating post-main-sequence star with dynamical masses. By combining Gaia astrometry with spectroscopic obtained with the Las Cumbres Observatory network (LCO), we find $M_1^\mathrm{dyn}$=0.99$\pm$0.05$M_\odot$ and $M_2^\mathrm{dyn}$=0.89$\pm$0.04$M_\odot$ for the primary and secondary, respectively. Asteroseismic parameters were extracted from photometry of the NASA \Kepler satellite. The mass from individual frequency modeling is $M_1^\mathrm{IF}$=0.92$\pm$0.01$M_\odot$. Taking into account the systematic uncertainty of 0.04$M_\odot$ for best fit models from individual frequency fitting, we find an agreement within 1.2$\sigma$. From scaling relations we obtain a mass range of 0.93 to 0.98$M_\odot$ by using the observed large frequency separations (\dnu) in the scaling relations for the primary. By using standard corrections for departures from the asymptotic regime of \dnu, we obtained a mass range of 0.83 to 1.03$M_\odot$. The upper ends of both ranges agree well with the dynamical mass of the primary. This approach provides the first empirical validation for main-sequence solar-like oscillators and opens a new window for validating asteroseismology. Through a dedicatded program targeting astrometric SB2 binary systems, ESA's PLATO space mission will provide will enlarge the benchmark sample substantially. - oai:arXiv.org:2601.14197v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-sa/4.0/ - P. G. Beck, T. Masseron, K. Pavlovski, D. Godoy-Rivera, S. Mathur, D. H. Grossmann, A. Hamy, D. B. Palakkatharappil, E. Panetier, R. A. Garc\'ia, J. Merc, Y. Lu, I. Amestoy, H. J. Deeg - - - The PAIRS project: a global formation model for planets in binaries. I. Effect of disc truncation on the growth of S-type planets - https://arxiv.org/abs/2601.14214 - arXiv:2601.14214v1 Announce Type: new -Abstract: Binary stars are as common as single stars. The number of detected planets orbiting binaries is rapidly increasing thanks to the synergy between transit surveys, Gaia and high-resolution direct imaging campaigns. However, global planet formation models around binary stars are still underdeveloped, which limits the theoretical understanding of planets orbiting binary star systems. Hereby we introduce the PAIRS project, which aims at building a global planet formation model for planets in binaries, and to produce planet populations synthesis to statistically compare theory and observations. In this first paper, we present the adaptation of the circumstellar disc to simulate the formation of S-type planets. The presence of a secondary star tidally truncates and heats the outer part of the circumprimary disc (and vice-versa for the circumsecondary disc), limiting the material to form planets. We implement and quantify this effect for a range of binary parameters by adapting the Bern Model of planet formation in its pebble-based form and for in-situ planet growth. We find that the disc truncation has a strong impact on reducing the pebble supply for core growth, steadily suppressing planet formation for binary separations below 160 au, when considering all the formed planets more massive than Mars. We find as well that S-type planets tend to form close to the central star with respect to the binary separation and disc truncation radius. Our newly developed model will be the basis of future S-type planet population synthesis studies. - oai:arXiv.org:2601.14214v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Julia Venturini, Arianna Nigioni, Maria Paula Ronco, Natacha Jungo, Alexandre Emsenhuber - - - The PAIRS project: a global formation model for planets in binaries. II. Gravitational perturbation effects from secondary stars - https://arxiv.org/abs/2601.14215 - arXiv:2601.14215v1 Announce Type: new -Abstract: Roughly half of Sun-like stars have at least one stellar companion, whereas it is widely assumed that most known exoplanets orbit single stars, largely due to observational biases. However, astrometric surveys, direct imaging, and speckle interferometry are steadily increasing the number of confirmed exoplanets in binaries. A stellar companion introduces additional effects, such as circumstellar disk truncation and gravitational perturbations, which can strongly impact planet formation. While global planet formation models, for example the Bern model, have been broadly applied to single stars, modeling S-type binaries requires key modifications to capture these effects. This study extends the Bern model by incorporating the gravitational influence of a stellar companion into its N-body integrator, allowing us to quantify how this perturbation affects planetary formation and final system architecture across a range of binary configurations. By comparing binary and single-star systems under identical initial conditions, we can assess the specific impact of binary-induced dynamics. We ran three sets of simulations: (i) a grid of in situ single-embryo cases to quantify gravitational effects; (ii) formation simulations with and without migration to compare outcomes with single-star analogs; and (iii) multi-embryo runs to evaluate impacts on multi-planetary systems. Planets forming beyond half the host star's Hill radius are much more likely to become unbound especially in systems with high binary eccentricity. Even within stable zones, growth is suppressed by both reduced material availability and increased eccentricity from stellar perturbations. Both disk truncation and stellar perturbations must be included to model planet formation in S-type binaries accurately. Neglecting either one will end up misrepresenting planetary growth and survival. - oai:arXiv.org:2601.14215v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Arianna Nigioni, Julia Venturini, Emeline Bolmont, Diego Turrini, Yann Alibert, Alexandre Emsenhuber - - - The [Fe XIII] Infrared 10747 Angstrom and 10798 Angstrom Lines in Novae - https://arxiv.org/abs/2601.14218 - arXiv:2601.14218v1 Announce Type: new -Abstract: The forbidden lines of [Fe XIII] at 10,747 Angstrom and 10,798 Angsrtom are among the most prominent lines in the near-infrared spectrum of the solar corona. They have been used routinely, both outside and during eclipses, as sensitive probes of the electron density and polarization in the solar corona. Many novae pass through a coronal phase, wherein the highly ionized nova ejecta have physical conditions that are remarkably similar to those of the solar corona. Many of the coronal emission lines that are seen are common to the spectra of both the Sun and novae. Yet, it appears that no robust detection of the [Fe XIII] lines has been made in a nova. Here we report the detection of these two infrared [Fe XIII]lines in the spectrum of the recurrent nova V3890 Sgr, taken 23.43 and 31.35 days after its August 2019 outburst. From their line strengths, we derive values of 10^10 per cubic cm and 10^[8.5-9] per cubic cm for the electron density on the two. The decrease in density between epochs can be explained if the density decreased with a power law n ~ r**alpha with a alpha inferred to be -3. The average temperature of the coronal gas is estimated to be T = (2.51\pm0.06) x 10^6~K. We find that recurrent novae with giant secondaries, including T CrB whose eruption is imminent, are the most suitable sources for further detections of the [Fe XIII] lines. epochs. - oai:arXiv.org:2601.14218v1 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - D. P. K. Banerjee, C. E. Woodward, A. Evans, T. R. Geballe, V. Joshi, S. Starrfield - - - Probing AGN duty cycle and cluster-driven morphology in a giant episodic radio galaxy - https://arxiv.org/abs/2601.14219 - arXiv:2601.14219v1 Announce Type: new -Abstract: The evolution of radio jet morphology and its energetics is significantly influenced by the environment in which the host galaxy resides. As giant radio galaxies (GRGs) often extend to the scale of entire galaxy clusters ($\sim$Mpc) and beyond, they are a suitable class of objects for studying jet--intracluster medium interactions. This paper presents a multiwavelength study of a GRG, J1007+3540, using the LOFAR Two-metre Sky Survey second data release (LoTSS DR2) at 144 MHz and the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400 MHz. The source has a projected linear extension of 1.45 Mpc and is hosted by MaxBCG J151.77665+35.67813, within the WHL 100706.4+354041 cluster. At both frequencies, the source exhibits clear signatures of recurrent jet activity, a one-sided, extended, tail-like diffuse structure with a morphological break in the tail. The estimated radiative ages of the inner lobes and outer north lobe are $\sim$140 Myr and $\sim$240 Myr, respectively. In addition to the radio analysis, we performed optical--to--infrared spectral energy distribution modelling. The host galaxy is an evolved elliptical system with a stellar mass of $\log_{10}(M_\star/M_\odot) = 11.0$ and an old stellar population age of $\sim$12 Gyr. The high infrared-derived star formation rate ($\sim106~M_\odot$~yr$^{-1}$) of the source implies significant dust-obscured star formation, potentially linked to merger-driven gas inflows. J1007+3540 presents a rare combination of a restarted jet, a detached tail-like structure, and unusual spectral flattening beyond the tail break, which is very rare to report together in a GRG. This rare and remarkable system offers a unique laboratory for probing the interplay between active galactic nucleus activity, star formation, and environmental effects in cluster-surrounded GRGs. - oai:arXiv.org:2601.14219v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1093/mnras/staf2038 - Monthly Notices of the Royal Astronomical Society, 2026, 545, Issue 4 - Shobha Kumari, Sabyasachi Pal, Surajit Paul, Marek Jamrozy - - - Revisiting the Matter Creation Process: Observational Constraints on Gravitationally Induced Dark Energy and the Hubble Tension - https://arxiv.org/abs/2601.14222 - arXiv:2601.14222v1 Announce Type: new -Abstract: The persistent Hubble tension and the lack of a fundamental explanation for dark energy motivate the exploration of alternative mechanisms capable of reproducing late-time cosmic acceleration. In this work, we revisit gravitationally induced particle creation as a phenomenological non-equilibrium process that can effectively mimic a dynamical dark-energy component. Within the thermodynamic framework of open systems, we model the production of an unspecified particle species with constant intrinsic equation-of-state parameter and consider four phenomenological parametrisations of the particle-creation rate. The modified continuity and Friedmann equations lead to an effective negative pressure and a redshift-dependent effective equation of state, which we constrain using Cosmic Chronometers, Pantheon+ supernovae, DESI DR2 BAO, a compressed CMB likelihood, and SH0ES data. Using the full dataset combination, we find that particle-creation models provide fits comparable to $\Lambda$CDM, yielding $H_0 \simeq 69.3\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$ and present-day effective dark-energy equation-of-state values close to $w^{\rm eff}_{\rm DE}(0)\simeq -1$, with all models predicting an accelerating Universe ($q_0\simeq -0.55$). When the Hubble tension is assessed using early- and late-time dataset splits, particle-creation scenarios reduce its statistical significance to the $\simeq 2.4\sigma$--$3\sigma$ level, compared to the $4.3\sigma$ discrepancy obtained in $\Lambda$CDM. Although deviations from $\Lambda$CDM remain mild and Bayesian model comparison indicates no statistical preference between models, gravitationally induced particle creation emerges as a viable late-time extension of the standard cosmological model and provides a consistent phenomenological framework for exploring departures from $\Lambda$CDM. - oai:arXiv.org:2601.14222v1 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Tiziano Schiavone, Mariaveronica De Angelis, Luis A. Escamilla, Giovanni Montani, Eleonora Di Valentino - - - Decoupling of large-scale, adiabatic inflationary perturbations from enhanced small-scale modes at one-loop - https://arxiv.org/abs/2601.14229 - arXiv:2601.14229v1 Announce Type: new -Abstract: We reconsider back-reaction from large amplitude, short-scale perturbations onto a long wavelength adiabatic mode. In a loop expansion of the long-mode power spectrum, this back-reaction appears first at 1-loop. Due to the separation between the long and short scales, the separate universe method provides a simple and efficient framework for this computation. In this paper, building on our earlier work, we employ a $\delta N$ formula for the long mode, which captures the effect of short scales. We show that back-reaction at 1-loop is due to either (i) non-linearity of the $\delta N$ formula, or (ii) 1-loop corrections to the initial conditions. We argue that contributions of type (ii) cannot themselves be described within the separate universe framework, but their properties can be constrained using soft theorems and a ''multi-point propagator'' expansion. When applied to a band of enhanced short-scale perturbations that crossed the horizon during inflation, our result shows that the loop correction decouples from their detailed properties. Furthermore, the back-reaction we obtain is scale-invariant. Its magnitude is model-dependent, but is degenerate with effects from modes that were still sub-horizon at the end of inflation. In this scenario (but not necessarily in all scenarios), we conclude that the effect is not observable. - oai:arXiv.org:2601.14229v1 - astro-ph.CO - gr-qc - hep-ph - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Laura Iacconi, David Mulryne, David Seery - - - Opportunities in AI/ML for the Rubin LSST Dark Energy Science Collaboration - https://arxiv.org/abs/2601.14235 - arXiv:2601.14235v1 Announce Type: new -Abstract: The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will produce unprecedented volumes of heterogeneous astronomical data (images, catalogs, and alerts) that challenge traditional analysis pipelines. The LSST Dark Energy Science Collaboration (DESC) aims to derive robust constraints on dark energy and dark matter from these data, requiring methods that are statistically powerful, scalable, and operationally reliable. Artificial intelligence and machine learning (AI/ML) are already embedded across DESC science workflows, from photometric redshifts and transient classification to weak lensing inference and cosmological simulations. Yet their utility for precision cosmology hinges on trustworthy uncertainty quantification, robustness to covariate shift and model misspecification, and reproducible integration within scientific pipelines. This white paper surveys the current landscape of AI/ML across DESC's primary cosmological probes and cross-cutting analyses, revealing that the same core methodologies and fundamental challenges recur across disparate science cases. Since progress on these cross-cutting challenges would benefit multiple probes simultaneously, we identify key methodological research priorities, including Bayesian inference at scale, physics-informed methods, validation frameworks, and active learning for discovery. With an eye on emerging techniques, we also explore the potential of the latest foundation model methodologies and LLM-driven agentic AI systems to reshape DESC workflows, provided their deployment is coupled with rigorous evaluation and governance. Finally, we discuss critical software, computing, data infrastructure, and human capital requirements for the successful deployment of these new methodologies, and consider associated risks and opportunities for broader coordination with external actors. - oai:arXiv.org:2601.14235v1 - astro-ph.IM - astro-ph.CO - cs.AI - cs.LG - stat.ML - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - LSST Dark Energy Science Collaboration, Eric Aubourg, Camille Avestruz, Matthew R. Becker, Biswajit Biswas, Rahul Biswas, Boris Bolliet, Adam S. Bolton, Clecio R. Bom, Rapha\"el Bonnet-Guerrini, Alexandre Boucaud, Jean-Eric Campagne, Chihway Chang, Aleksandra \'Ciprijanovi\'c, Johann Cohen-Tanugi, Michael W. Coughlin, John Franklin Crenshaw, Juan C. Cuevas-Tello, Juan de Vicente, Seth W. Digel, Steven Dillmann, Mariano Javier de Le\'on Dominguez Romero, Alex Drlica-Wagner, Sydney Erickson, Alexander T. Gagliano, Christos Georgiou, Aritra Ghosh, Matthew Grayling, Kirill A. Grishin, Alan Heavens, Lindsay R. House, Mustapha Ishak, Wassim Kabalan, Arun Kannawadi, Fran\c{c}ois Lanusse, C. Danielle Leonard, Pierre-Fran\c{c}ois L\'eget, Michelle Lochner, Yao-Yuan Mao, Peter Melchior, Grant Merz, Martin Millon, Anais M\"oller, Gautham Narayan, Yuuki Omori, Hiranya Peiris, Laurence Perreault-Levasseur, Andr\'es A. Plazas Malag\'on, Nesar Ramachandra, Benjamin Remy, C\'ecile Roucelle, Jaime Ruiz-Zapatero, Stefan Schuldt, Ignacio Sevilla-Noarbe, Ved G. Shah, Tjitske Starkenburg, Stephen Thorp, Laura Toribio San Cipriano, Tilman Tr\"oster, Roberto Trotta, Padma Venkatraman, Amanda Wasserman, Tim White, Justine Zeghal, Tianqing Zhang, Yuanyuan Zhang - - - A Quenched and Relatively Isolated Dwarf Galaxy in the Local Volume - https://arxiv.org/abs/2601.14248 - arXiv:2601.14248v1 Announce Type: new -Abstract: An increasing number of discoveries of isolated and quenched dwarf galaxies are challenging the idea that the present-day local environment of low-mass systems is the main determinant of their quenching. We present new Hubble Space Telescope (HST) data of one such system, the dwarf galaxy Canes Venatici C (CVn C). CVn C is a low-mass (3.4(+4.2-2.6)*10^6 M_sun) galaxy with a Tip of the Red Giant Branch distance of 8.43(+0.47-0.32) Mpc determined from the resolved stars in the HST imaging, which we also use to derive CVn C's structural parameters. CVn C's distance places CVn C in the Local Volume and in an isolated environment with the most tidally influential L* galaxy > 5Rvir away. Additional constraints from the HST color-magnitude diagram, archival Far-Ultraviolet (FUV), and neutral hydrogen (HI) data show that CVn C is quenched, with no evidence of star formation in the last 100 Myr and no detectable gas (MHI < 1.5*10^6 M_sun). Circumstantial evidence suggests that CVn C may have quenched via past interactions with the L* galaxy NGC 4631 (L_K = 10^10.4 L_sun), and was possibly sent on an extreme backsplash orbit by the tidal dissolution of a subhalo group. However, other quenching mechanisms-such as stripping via the cosmic web-cannot be ruled out. CVn C adds to the growing number of quenched dwarf galaxies in under-dense environments, a population that will be critical to defining the mass and environment regimes in which different quenching mechanisms operate. - oai:arXiv.org:2601.14248v1 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Tehreem N. Hai (Department of Physics and Astronomy, Rutgers University), Kristen B. W. McQuinn (Department of Physics and Astronomy, Rutgers University, Space Telescope Science Institute), Yao-Yuan Mao (Department of Physics and Astronomy, University of Utah), Roger E. Cohen (Department of Physics and Astronomy, Rutgers University), David Shih (Department of Physics and Astronomy, Rutgers University), Erik Tollerud (Space Telescope Science Institute), Joseph A. Breneman (Department of Physics and Astronomy, Rutgers University), Andrew E. Dolphin (Raytheon, Steward Observatory, University of Arizona), Max J. B. Newman (Space Telescope Science Institute), Adam Smercina (Space Telescope Science Institute) - - - Using observations of escaping H/He to constrain the atmospheric composition of sub-Neptunes - https://arxiv.org/abs/2601.14254 - arXiv:2601.14254v1 Announce Type: new -Abstract: The internal composition of sub-Neptunes remains a prominent unresolved question in exoplanetary science. We present a technique to place constraints on envelope mean molecular weight that utilises observations of escaping hydrogen or helium exospheres. This method is based on a simple timescale argument, which states that sub-Neptunes require a sufficiently large hydrogen or helium reservoir to explain on-going escape at their observed rates. This then naturally leads to an upper limit on atmospheric mean molecular weight. We apply this technique to archetypal sub-Neptunes, namely GJ-436 b, TOI-776 b and TOI-776 c, which have all been observed to be losing significant hydrogen content as well as relatively featureless transit spectra when observed with JWST. Combining constraints from atmospheric escape and transit spectroscopy in the case of TOI-776 c allows us to tentatively rule out the high mean molecular weight scenario, pointing towards a low mean molecular weight atmosphere with high-altitude aerosols muting spectral features in the infra-red. Finally, we reframe our analysis to the hycean candidate K2-18 b, which has also been shown to host a tentative escaping hydrogen exosphere. If such a detection is robust, we infer a hydrogen-rich envelope mass fraction of $\log f_\text{env} = -1.67\pm0.78$, which is inconsistent with the hycean scenario at the $\sim 4\sigma$ level. This latter result requires further observational follow-up to confirm. - oai:arXiv.org:2601.14254v1 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - James G. Rogers, James E. Owen, Ethan Schreyer, James Kirk - - - A self-consistent explanation of the MeV line in GRB 221009A unveils a dense circum-stellar medium - https://arxiv.org/abs/2601.14257 - arXiv:2601.14257v1 Announce Type: new -Abstract: GRB~221009A has been the brightest gamma-ray burst (GRB) observed to date, and its afterglow has been characterised with unprecedented detail at TeV energies by LHAASO. Quite puzzlingly, it is also the most energetic GRB known. Among the riddles posed by this mysterious source, however, the sheer energetics are hardly the most intriguing: an unprecedented, narrow, luminous emission line at around 10 MeV has been uncovered by a detailed spectral analysis of \textit{Fermi}/GBM data immediately following the brightest peak in the GRB prompt emission and the peak of the TeV afterglow. As noted in the discovery article, the temporal evolution of the line properties can be explained as being due to high-latitude emission from a geometrically thin, relativistically expanding shell where annihilation of a large number of electron-positron pairs took place. We show that this interpretation yields stringent constraints on the properties of such shell, that point to a process that happens at radii typical of external shocks. We then demonstrate that the shell could have been the blastwave associated with the GRB precursor, with the line arising after pair loading of such blastwave as it was illuminated by the bright and hard radiation of the GRB main event. The scenario, which also explains the abrupt initial rise of the LHAASO afterglow, requires the progenitor of the GRB to have been surrounded by a circum-stellar medium (CSM) extending out to a few $10^{15}\,\mathrm{cm}$, with a density $n_\mathrm{ext}\sim 10^{8}-10^{9}\,\mathrm{cm^{-3}}$ reminiscent of those found from studies of Type IIn supernovae. This provides a precious clue to the nature of the progenitor of this peculiar GRB, which could also be present in other bursts that feature a long quiescence followed by a bright emission episode with a hard spectrum. - oai:arXiv.org:2601.14257v1 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - O. S. Salafia, A. Celotti, E. Sobacchi, L. Nava, G. Oganesyan, G. Ghirlanda, S. Boula, M. E. Ravasio, G. Ghisellini - - - Probing super-heavy dark matter with ultra-high-energy gamma rays - https://arxiv.org/abs/2601.11703 - arXiv:2601.11703v1 Announce Type: cross -Abstract: We refine the constraints on the lifetime of decaying super-heavy dark matter particles (SHDM), with masses ranging from $10^7$ to $10^{15}$ GeV, by analyzing ultra-high-energy (UHE) gamma-ray data. Our approach involves an accurate comparison of the primary gamma-ray emissions resulting from prompt SHDM decays in the galactic halo with the most recent upper limits on isotropic UHE gamma-ray fluxes provided by various extensive air shower experiments. We demonstrate that a precise consideration of the field of view and the geometric acceptance of different UHE gamma-ray observatories has significant implications for the inferred limits of dark matter lifetime. In addition, we examine the influence of uncertainties linked to the current models of the galactic dark matter distribution, employing diverse halo density profiles while varying both their radial extent and the local dark matter density. Our findings indicate that the newly established UHE gamma-ray constraints are marginally less stringent than earlier evaluations, thereby revisiting the SHDM parameter space and allowing for observable neutrino fluxes. - oai:arXiv.org:2601.11703v1 - hep-ph - astro-ph.CO - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Marco Chianese, Ninetta Saviano, Sara Cesare, Vincenzo M. Grieco, Valentina Nasti, Francesca Spinnato, Alessandro Tiano - - - Stimulated radiation from superradiant scalar cloud in scalar-tensor theory - https://arxiv.org/abs/2601.11988 - arXiv:2601.11988v1 Announce Type: cross -Abstract: Scalar-tensor theories predict fundamental scalar fields of considerable interest in astrophysics and cosmology. We investigate the superradiant instability of scalar clouds around Kerr black holes, showing that stimulated decay generates detectable electromagnetic signals. The growth of the superradiant scalar cloud differs from that of other bosonic fields and depends sensitively on the matter distribution surrounding the black hole, which originates from the scalar-matter coupling realized by the chameleon mechanism in modified gravity theories. In non-uniform matter distributions, stimulated emission from scalar clouds offers an observational signature that distinguishes fundamental scalars from other light bosonic fields. - oai:arXiv.org:2601.11988v1 - gr-qc - astro-ph.HE - hep-ph - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Wenyi Wang, Sousuke Noda, Taishi Katsuragawa - - - The gravitational energy-momentum pseudo-tensor in $f(Q)$ non-metric gravity - https://arxiv.org/abs/2601.12088 - arXiv:2601.12088v1 Announce Type: cross -Abstract: We derive the affine tensor associated with the energy and momentum densities of both gravitational and matter fields, the complex pseudo-tensor, for $f(Q)$ non-metric gravity, the straightforward extension of Symmetric Teleparallel Equivalent of General Relativity (STEGR), characterized by a flat, torsion-free, non-metric connection. The local conservation of energy-momentum complex on-shell is satisfied through a continuity equation. An important analogy is pointed out between gravitational pseudo-tensor of teleparallel $f(T)$ gravity, in the Weitzenb\"ock gauge, and the same object of symmetric teleparallel $f(Q)$ gravity, in the coincident gauge. Furthermore, we perturb the gravitational pseudo-tensor $\tau^{\alpha}_{\phantom{\alpha}\lambda}$ in the coincident gauge up to the second order in the metric perturbation, obtaining a useful expression for the power carried by the related gravitational waves. We also present an application of the gravitational pseudotensor, determining the gravitational energy density of a Schwarzschild spacetime in STEGR gravity, adopting the concident gauge. Finally, analyzing the conserved quantities on manifolds, the Stokes theorem can be formulated for generic affine connections - oai:arXiv.org:2601.12088v1 - gr-qc - astro-ph.HE - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Salvatore Capozziello, Maurizio Capriolo, Gaetano Lambiase - - - Forbidden dark matter assisted by first-order phase transition and associated gravitational waves - https://arxiv.org/abs/2601.12319 - arXiv:2601.12319v1 Announce Type: cross -Abstract: We propose a simple yet testable framework for light fermion dark matter (DM) with mass in the MeV--GeV range, charged under a dark $U(1)_D$ gauge symmetry. The $U(1)_D$ is spontaneously broken by a scalar field $\Phi$, giving mass to the dark gauge boson $X_D$. The dominant DM annihilation proceeds via a forbidden channel, where the DM pair annihilates into slightly heavier dark gauge bosons and scalars after the dark-sector phase transition. Once the dark-sector phase transition occurs, the induced mass gap activates the forbidden annihilation channel, which in turn determines the DM relic abundance and naturally suppresses late-time annihilation. As a result, the scenario avoids stringent cosmic microwave background and indirect detection constraints that typically exclude thermal light DM. Moreover, the same symmetry-breaking phase transition is strongly first-order, producing a stochastic gravitational wave background that could be probed by upcoming space-based interferometers and pulsar timing arrays. We demonstrate that achieving the observed DM abundance tightly correlates the DM mass with the nucleation temperature of the phase transition. Thus, this setup links the DM relic abundance, dark-sector dynamics, and gravitational wave signals, offering complementary paths for discovery in both terrestrial and cosmological observations. - oai:arXiv.org:2601.12319v1 - hep-ph - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Satyabrata Mahapatra, Partha Kumar Paul, Narendra Sahu - - - Revisiting $^7$Be Weak and Radiative Transition Rates in Big Bang Nucleosynthesis: Implications for the Primordial Lithium Problem - https://arxiv.org/abs/2601.12438 - arXiv:2601.12438v1 Announce Type: cross -Abstract: The primordial 7Li abundance predicted by standard Big Bang Nucleosynthesis (BBN) exceeds that inferred from old, metal-poor stars by a factor of about 3-4. In standard BBN, most primordial 7Li is produced as 7Be in the early Universe and later converted by electron capture. Additional production or destruction channels of 7Be, such as proton capture or antineutrino capture during BBN, may therefore affect the final lithium yield. We quantify the depletion of 7Be due to in-situ electron capture, including the associated antineutrino channel, positron decay from nuclear excited states, and proton capture through the radiative 7Be(p,gamma)8B reaction. We also investigate stimulated emission induced by the dense photon background during the nuclear statistical equilibrium epoch, as well as a three-body Auger-like variant transferring the capture energy to a continuum electron. Decay rates are computed using first-order perturbation theory, modelling weak interactions with a Fermi contact term and factorising hadronic and leptonic currents. Thermally averaged rates are obtained by folding cross-sections with Maxwell-Boltzmann distributions and accounting for particle densities in the temperature range 10-100 keV. We find that the electron-capture rate decreases rapidly with temperature and is significantly enhanced by the inclusion of the antineutrino channel. Stimulated emission and plasma screening increase the radiative proton-capture rate by only 1-3 percent at temperatures around 87 keV. The Auger-like channel contributes at the level of a few thousandths of a percent and becomes negligible at lower temperatures. Overall, our total rate revises previous estimates by nearly an order of magnitude. Electron capture, proton capture, and positron decay provide corrections to the dominant depletion channel 7Be(n,p)7Li. - oai:arXiv.org:2601.12438v1 - nucl-th - astro-ph.CO - astro-ph.HE - astro-ph.SR - physics.comp-ph - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Simone Taioli, Francesca Triggiani, Stefano Simonucci - - - Plasmoid formation via competing lower-hybrid drift and Kelvin-Helmholtz instabilities: A hybrid kinetic-gyrokinetic simulation study - https://arxiv.org/abs/2601.12466 - arXiv:2601.12466v1 Announce Type: cross -Abstract: We investigate the nonlinear formation of plasmoids in 2D low-beta current sheets through the interplay between the Kelvin-Helmholtz instability (KHI) and the lower-hybrid drift instability (LHDI). Using a hybrid kinetic-gyrokinetic model-based Super Simple Vlasov (ssV) code with fully kinetic ions and drift-kinetic electrons, we simulate Harris-type current sheets and velocity shear layers with strong cross-field density gradients. Our central hypothesis is that steep density gradients drive LHDI, which can grow faster than KHI and initiate an inverse cascade from kinetic to fluid scales, potentially suppressing KHI. Our simulations confirm that, in thin current sheets, LHDI develops rapidly at the sheet edges and nonlinearly merges into larger-scale magnetic islands before KHI can evolve. These LHDI-driven structures distort the velocity shear and suppress classical KH vortices. In contrast, for thicker current sheets or weaker density gradients, KHI dominates and produces the expected rolled-up vortices and associated plasmoids. These findings demonstrate that LHDI-induced turbulence can act as both a seed and a regulator of plasmoid-generating instabilities, mediating cross-scale energy transfer. This mechanism is relevant to thin boundary layers in space plasmas, such as the solar wind magnetosphere interface, and suggests that microturbulence can govern large-scale magnetic topology during collisionless reconnection. - oai:arXiv.org:2601.12466v1 - physics.plasm-ph - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - S. Thatikonda, F. N. De Oliveira-Lopes, A. Mustonen, K. Pommois, D. Told, F. Jenko - - - Lessons Learned from Structural Design and Vibration Testing of 50-kg Microsatellites Deployed from the International Space Station - https://arxiv.org/abs/2601.12840 - arXiv:2601.12840v1 Announce Type: cross -Abstract: Hokkaido University and Tohoku University have been developing and operating a constellation of 50-cm-class microsatellites for Earth observation. DIWATA-1, launched in 2016, was deployed into a circular orbit at an altitude of approximately 400 km from the International Space Station (ISS). For the subsequent satellite developed in 2021, the structural design and vibration test campaign were optimized to meet a strict one-year development schedule. This paper summarizes how the structural design of the previous satellite was reviewed and updated, and how the vibration test was successfully completed in a single trial to minimize schedule and technical risks. These lessons learned provide valuable insights, as there are only a limited number of reported cases of 50-kg-class microsatellites deployed from the ISS. - oai:arXiv.org:2601.12840v1 - eess.SY - astro-ph.IM - cs.SY - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Yuji Sakamoto, Junichi Kurihara, Shinya Fujita, Yuji Sato, Toshinori Kuwahara - - - Anisotropic Collective Excitations of Bose Gases in Modified Newtonian Dynamics - https://arxiv.org/abs/2601.12848 - arXiv:2601.12848v1 Announce Type: cross -Abstract: Collective excitations are fundamental in quantum many-body physics, yet their spectra have traditionally been studied within Newtonian dynamics. In this Letter, we investigate collective excitations in Bose gases under Modified Newtonian Dynamics (MOND). We derive an anisotropic excitation spectrum in the MOND regime. This anisotropy arises directly from the intrinsic nonlinear structure of the MOND Poisson equation, forming a distinctive signature of the modified gravitational response. We then analyze the Jeans instability, obtaining analytic expressions for the direction-dependent critical wavelength and mass. These results advance our understanding of collective behavior in quantum systems under modified dynamics and establish clear theoretical signatures for testing MOND-like effects in quantum simulators. - oai:arXiv.org:2601.12848v1 - cond-mat.quant-gas - astro-ph.GA - cond-mat.stat-mech - quant-ph - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ning Liu - - - System Analysis and Pre-Flight Evaluation of Deployable Solar Panels for 3U CubeSat HOKUSHIN-1 - https://arxiv.org/abs/2601.12851 - arXiv:2601.12851v1 Announce Type: cross -Abstract: This paper describes the system design methodology derived from the development and evaluation tests of deployable solar panels to be mounted on a 3U CubeSat. The study mainly includes structural analysis, thermal analysis, and a review of vibration test results. Hokkaido University is developing the 3U CubeSat HOKUSHIN-1 in collaboration with Tohoku University and Muroran Institute of Technology. Deployable solar panels are a key technology for future planned lunar exploration missions, as they enable power-intensive communication and propulsion required for orbit control. The satellite also demonstrates a newly developed compact and efficient propulsion system. The satellite has dimensions of approximately 10x10x34 cm, a mass of 3.99 kg, and will be deployed into a circular orbit at an altitude of about 400 km with an orbital inclination of 51.6 degrees from the International Space Station. - oai:arXiv.org:2601.12851v1 - eess.SY - astro-ph.IM - cs.SY - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Yuji Sakamoto, Masaki Aoi, Sho Suzuki, Takumi Haga, Shumpei Hosokawa, Yuma Abe, Yuya Tasaki, Tsuyoshi Totani, Sou Nakamura, Masaharu Uchiumi, Shinya Fujita - - - Report on Earth Observation Missions and Ground Station Management using On-Demand Satellite Operation System - https://arxiv.org/abs/2601.12857 - arXiv:2601.12857v1 Announce Type: cross -Abstract: Since the launch of its first satellite in 2009, Tohoku University has continuously developed and operated Earth observation satellites and engineering demonstration satellites in the 50cm-class and CubeSat-class (up to 3U). The 50cm-class satellite launched into operation in 2021 enabled efficient operations through cloud-based management functions for both the satellite and ground stations, including automatic command generation. By 2022, up to eight operational satellites were simultaneously managed on a daily basis using three ground stations (Sendai, Hakodate, and Sweden). This paper presents the operational achievements to date and introduces the system that supports efficient satellite operations - oai:arXiv.org:2601.12857v1 - eess.SY - astro-ph.IM - cs.SY - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Yuji Sakamoto - - - Baryon-dark matter coincidence in Randall-Sundrum Model - https://arxiv.org/abs/2601.13315 - arXiv:2601.13315v1 Announce Type: cross -Abstract: Within the framework of the extra-dimensional Randall-Sundrum set-up, we investigate the freeze-in production of Standard Model (SM) gauge-singlet scalar, fermionic, and massive vector dark matter (DM). Assuming that both the DM and SM fields reside on the IR brane and interact solely through the graviton and radion, we demonstrate that the observed DM relic abundance measured by Planck can be achieved across a wide range of reheating temperatures, all while naturally addressing the hierarchy problem, satisfying constraints from collider, early Universe cosmology including $\Delta{N}_{\rm eff}$. We further show that the same set-up can accommodate TeV-scale leptogenesis capable of generating the observed baryon asymmetry of the Universe. Remarkably, we find that current graviton searches at the Large Hadron Collider (LHC) already impose strong constraints on the reheating temperature in this scenario. - oai:arXiv.org:2601.13315v1 - hep-ph - astro-ph.CO - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Basabendu Barman, Ashmita Das, Partha Kumar Paul, Narendra Sahu, Rakesh Kumar SivaKumar - - - AMACA: Astronomy education with a Multi-sensory, Accessible, and Circular Approach - https://arxiv.org/abs/2601.13326 - arXiv:2601.13326v1 Announce Type: cross -Abstract: The AMACA project (Astronomy education with a Multi-sensory, Accessible, and Circular Approach) develops multi-sensory activities for accessible education and engagement in astronomy. Despite promising innovations, existing resources are often poorly documented, designed for one-time events, expensive, and lack interdisciplinary collaboration, user testing, and broad dissemination. AMACA addresses these challenges by creating multi-sensory activities for education and outreach, with a particular focus on accessibility for people with sensory disabilities. A circular approach informs its educational structure: (1) a PhD course on multi-sensory astronomy outreach develops hands-on activities with the support of astronomers, psychologists, and organizations for the visually impaired and the deaf; (2) PhD candidates teach High School (HS) students how to deliver the activities; (3) HS students lead the activities at the Astronomy Festival "The Universe in All Senses"; (4) HS students train teachers to implement the activities in their classrooms. AMACA also develops tools to guide project development and track participants' learning. Key findings show improved communication and accessibility awareness among PhD candidates, increased emotional engagement with astronomy among HS students, enhanced public engagement with research and accessibility awareness, and high teacher satisfaction with the flipped-roles, hands-on approach. Overall, AMACA enhances accessibility and engagement in astronomy education across audiences. - oai:arXiv.org:2601.13326v1 - physics.ed-ph - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1080/21548455.2025.2594048 - Rachele Toniolo, Anita Zanella, Andrea Cottinelli, Giovanni Liuzzi, Sara Ricciardi, Massimo Grassi, Stefano Delle Monache - - - Universal Dense-Matter Trace Anomaly Inferred from Collective Flow in Heavy-Ion Collisions and Global Properties of Neutron Stars - https://arxiv.org/abs/2601.13374 - arXiv:2601.13374v1 Announce Type: cross -Abstract: The trace anomaly of dense matter, $\Delta \equiv 1/3 - P/\varepsilon$, defined in terms of the ratio of pressure $P$ to energy density $\varepsilon$, quantifies deviations from conformal symmetry and plays a central role in both the hydrodynamic response and gravitational equilibrium. While $\Delta(\varepsilon)$ has recently been inferred from neutron star observations, we report the first Bayesian extraction of the trace anomaly from collective flow observables in intermediate-energy heavy-ion collisions. By employing transport-model simulations that explicitly decouple the cold-matter mean-field potential from thermal effects, we directly constrain the cold dense-matter equation of state (EOS). Remarkably, the trace anomaly inferred from laboratory flow data agrees quantitatively, within $68\%$ credible intervals, with independent astrophysical posterior bands. This nontrivial agreement demonstrates that heavy-ion collisions and neutron star observations probe the same universal macroscopic properties of dense matter, establishing the trace anomaly as a composition-insensitive descriptor of dense matter across widely different physical environments. - oai:arXiv.org:2601.13374v1 - nucl-th - astro-ph.HE - hep-ph - nucl-ex - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/publicdomain/zero/1.0/ - Bao-An Li - - - An upper limit on cosmological chiral gravitational wave background - https://arxiv.org/abs/2601.13532 - arXiv:2601.13532v1 Announce Type: cross -Abstract: Within the standard framework in which electroweak sphaleron processes relate lepton and baryon number, we derive an upper limit on the amplitude of a chiral gravitational wave background produced prior to the electroweak epoch. This bound is independent of the production time of chiral GWs for superhorizon modes, while it becomes sensitive to the production time for subhorizon modes. For sufficiently high reheating temperatures, the bound becomes significantly more stringent than the conventional big bang nucleosynthesis constraints at frequencies above the MHz scale, thereby providing a powerful and \emph{model-independent} probe of parity-violating physics in the early Universe. - oai:arXiv.org:2601.13532v1 - hep-ph - astro-ph.CO - gr-qc - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Mohammad Ali Gorji, Ashu Kushwaha, Teruaki Suyama - - - AAFIYA: Antenna Analysis in Frequency-domain for Impedance and Yield Assessment - https://arxiv.org/abs/2601.13583 - arXiv:2601.13583v1 Announce Type: cross -Abstract: This paper presents AAFIYA (Antenna Analysis in Frequency-domain for Impedance and Yield Assessment), a modular Python toolkit for automated characterization of radio-frequency antennas using measurement and simulation data. The toolkit provides a unified workflow for processing S-parameters, impedance, realized gain, beam patterns, polarization metrics, and calibration-based yield estimation, with support for standard Touchstone files and beam pattern data. AAFIYA is validated using measurements from an electromagnetic anechoic chamber involving Log Periodic Dipole Array (LPDA) reference antennas and Askaryan Radio Array (ARA) Bottom Vertically Polarized antennas over 100-850 MHz. Extracted metrics, including impedance matching, realized gain patterns, vector effective lengths, and cross-polarization ratio, are compared against full-wave simulations from HFSS and WIPL-D, showing good agreement across frequency and angle. The results demonstrate that AAFIYA enables accurate, reproducible, and publication-ready antenna analysis, and provides a flexible foundation for future extensions, including automated optimization and data-driven antenna design. - oai:arXiv.org:2601.13583v1 - physics.ins-det - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Mohammad Ful Hossain Seikh, Rachel Jarvis, James Stiles - - - Cosmological Budget of Entropy from Merging Black Holes - https://arxiv.org/abs/2601.13621 - arXiv:2601.13621v1 Announce Type: cross -Abstract: Black holes contain more entropy than any other component of the observable universe. Gravitational-wave observations from LIGO and Virgo have shown evidence of a previously unknown black hole mass range, which provides new information to update the entropy budget. Increases in entropy due to binary black hole mergers, as implied in the second law of thermodynamics, should also be added to the budget. In this study, we update the cosmological entropy budget for black holes in the stellar to lite-intermediate-mass range $(5-300~M_\odot)$, originating from either supernovae or binary mergers, by utilizing a suite of population synthesis models and phenomenological fits derived from numerical relativity. We report three new insights: Firstly, the cumulative entropy from merging black holes surpasses the total entropy from cosmic microwave background photons around the onset of the Over-massive Black Hole Galaxy phase at $z\sim 12$, suggesting that mergers played a more significant role in shaping the thermodynamic state of the early universe than relic radiation. Secondly, if primordial black holes constitute a nonzero fraction of dark matter, their early binary mergers establish an ``entropy floor" in the Dark Ages and can dominate the cumulative merger-generated entropy history even for small abundances. Thirdly, by computing the cosmological density parameters, we highlight the thermodynamic asymmetry in black hole mergers, where the production of gravitational-wave energy is inefficient compared to the immense generation of Bekenstein-Hawking entropy. - oai:arXiv.org:2601.13621v1 - gr-qc - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Siyuan Chen, Karan Jani, Thomas W. Kephart - - - RNLE: Residual neural likelihood estimation and its application to gravitational-wave astronomy - https://arxiv.org/abs/2601.13857 - arXiv:2601.13857v1 Announce Type: cross -Abstract: Simulation-based inference provides a powerful framework for Bayesian inference when the likelihood is analytically intractable or computationally prohibitive. By leveraging machine-learning techniques and neural density estimators, it enables flexible likelihood or posterior modeling directly from simulations. We introduce Residual Neural Likelihood Estimation (RNLE), a modification of Neural Likelihood Estimation (NLE) that learns the likelihood of non-Gaussian noise in gravitational-wave detector data. Exploiting the additive structure of the signal and noise generation processes, RNLE directly models the noise distribution, substantially reducing the number of simulations required for accurate parameter estimation and improving robustness to realistic noise artifacts. The performance of RNLE is demonstrated using a toy model, simulated gravitational-wave signals, and real detector noise from ground based interferometers. Even in the presence of loud non-Gaussian transients, glitches, we show that RNLE can achieve reliable parameter recovery when trained on appropriately constructed datasets. We further assess the stability of the method by quantifying the variability introduced by retraining the conditional density estimator on statistically identical datasets with different optimization seeds, referred to as training noise. This variability can be mitigated through an ensemble approach that combines multiple RNLE models using evidence-based weighting. An implementation of RNLE is publicly available in the sbilby package, enabling its deployment within gravitational-wave astronomy and a broad range of scientific applications requiring flexible, simulation-based likelihood estimation. - oai:arXiv.org:2601.13857v1 - gr-qc - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Mattia Emma, Gregory Ashton - - - Quasi-linear approach of bi-Kappa distributed electrons with dynamic $\kappa$ parameter. EMEC instability - https://arxiv.org/abs/2601.13888 - arXiv:2601.13888v1 Announce Type: cross -Abstract: In recent years, significant progress has been made in the velocity-moment-based quasi-linear (QL) theory of waves and instabilities in plasmas with nonequilibrium velocity distributions (VDs) of the Kappa (or $\kappa$) type. However, the temporal variation of the parameter $\kappa$, which quantifies the presence of suprathermal particles, is not fully captured by such a QL analysis, and typically $\kappa$ remains constant during plasma dynamics. We propose a new QL modeling that goes beyond the limits of a previous approach, realistically assuming that the quasithermal core cannot evolve independently of energetic suprathermals. The case study is done on the electron-cyclotron (EMEC) instability generated by anisotropic bi-Kappa electrons with $A=T_\perp/T_\parallel > 1$ ($\parallel, \perp$ denoting directions with respect to the background magnetic field). The parameter $\kappa$ self-consistently varies through the QL equation of kurtosis (fourth-order moment) coupled with temporal variations of the temperature components, relaxing the constraint on the independence of the low-energy (core) electrons and suprathermal high-energy tails of VDs. The results refine and extend previous approaches. A clear distinction is made between regimes that lead to a decrease or an increase in the $\kappa$ parameter with saturation of the instability. What predominates is a decrease in $\kappa$, i.e., an excess of suprathermalization, which energizes suprathermal electrons due to self-generated wave fluctuations. Additionally, we found that VDs can evolve toward a quasi-Maxwellian shape (as $\kappa$ increases) primarily in regimes with low beta and initial kappa values greater than five. Instability-driven relaxation only partially resolves temperature anisotropy in bi-Kappa electron VDs, as wave fluctuations generally act to further energize suprathermal electrons. - oai:arXiv.org:2601.13888v1 - physics.plasm-ph - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.1051/0004-6361/202558299 - Pablo S Moya, Roberto E Navarro, Marian Lazar, Peter H Yoon, Rodrigo A L\'opez, Stefaan Poedts - - - Influence of Finite-Nuclei Constraints on High-Density Transitions and Neutron Star Properties - https://arxiv.org/abs/2601.14194 - arXiv:2601.14194v1 Announce Type: cross -Abstract: We construct posterior distributions of the equation of state (EoS) for matter beyond the inner crust of neutron stars by incorporating finite nuclei (FN) constraints within relativistic mean field models. These constraints are implemented in three complementary ways: (i) through theoretical bounds on the EoS, (ii) implicitly via nuclear matter parameters, and (iii) explicitly by enforcing consistency with experimental binding energies and charge radii of selected nuclei. The resulting low-density nucleonic EoSs are subsequently matched to a model-agnostic speed-of-sound parametrization, constrained by astrophysical observations, including NICER mass-radius measurements, tidal deformability limits from GW170817, and lower bounds on the maximum neutron-star mass inferred from radio pulsar observations. We find that the admissible range of the transition density is strongly sensitive to the choice of the low-density EoS. In particular, the inclusion of explicit FN constraints significantly reduces the allowed parameter space of the nucleonic EoS at low densities, narrowing the transition-density range by nearly a factor of two. Consequently, neutron-star properties inferred from EoSs with explicit FN constraints differ substantially, with especially pronounced effects for low-mass neutron stars and their correlations with nuclear matter parameters. A quantitative comparison, using metrics based on Mahalanobis distance, shows consistency of the explicit constraints with PSRs J0740+6620, J0030+0451, and J0437-4715, but suggest a possible tension with PSR J0614-3329. These findings underscore the critical importance of a consistent treatment of finite-nuclei properties for reliably inferring the behavior of high-density matter and the presence of possible phase transitions from astrophysical observations. - oai:arXiv.org:2601.14194v1 - nucl-th - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Anagh Venneti, Sarmistha Banik, Bijay K Agrawal - - - The Cosmic Expansion History from Line-Intensity Mapping - https://arxiv.org/abs/1907.10065 - arXiv:1907.10065v2 Announce Type: replace -Abstract: Line-intensity mapping (LIM) of emission from star-forming galaxies can be used to measure the baryon acoustic oscillation (BAO) scale as far back as the epoch of reionization. This provides a standard cosmic ruler to constrain the expansion rate of the Universe at redshifts which cannot be directly probed otherwise. In light of growing tension between measurements of the current expansion rate using the local distance ladder and those inferred from the cosmic microwave background, extending the constraints on the expansion history to bridge between the late and early Universe is of paramount importance. Using a newly derived methodology to robustly extract cosmological information from LIM, which minimizes the inherent degeneracy with unknown astrophysics, we show that present and future experiments can gradually improve the measurement precision of the expansion rate history, ultimately reaching percent-level constraints on the BAO scale. Specifically, we provide detailed forecasts for the SPHEREx satellite, which will target the H$\alpha$ and Lyman-$\alpha$ lines, and for the ground-based COMAP instrument -- as well as a future stage-3 experiment -- that will target the CO rotational lines. Besides weighing in on the so-called Hubble tension, reliable LIM cosmic rulers can enable wide-ranging tests of dark matter, dark energy and modified gravity. - oai:arXiv.org:1907.10065v2 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/PhysRevLett.123.251301 - Phys. Rev. Lett. 123, 251301 (2019) - Jos\'e Luis Bernal, Patrick C. Breysse, Ely D. Kovetz - - - A User's Guide to Extracting Cosmological Information from Line-Intensity Maps - https://arxiv.org/abs/1907.10067 - arXiv:1907.10067v2 Announce Type: replace -Abstract: Line-intensity mapping (LIM) provides a promising way to probe cosmology, reionization and galaxy evolution. However, its sensitivity to cosmology and astrophysics at the same time is also a nuisance. Here we develop a comprehensive framework for modelling the LIM power spectrum, which includes redshift space distortions and the Alcock-Paczynski effect. We then identify and isolate degeneracies with astrophysics so that they can be marginalized over. We study the gains of using the multipole expansion of the anisotropic power spectrum, providing an accurate analytic expression for their covariance, and find a 10%-60% increase in the precision of the baryon acoustic oscillation scale measurements when including the hexadecapole in the analysis. We discuss different observational strategies when targeting other cosmological parameters, such as the sum of neutrino masses or primordial non-Gaussianity, finding that fewer and wider bins are typically more optimal. Overall, our formalism facilitates an optimal extraction of cosmological constraints robust to astrophysics. - oai:arXiv.org:1907.10067v2 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/PhysRevD.100.123522 - Phys. Rev. D 100, 123522 (2019) - Jos\'e Luis Bernal, Patrick C. Breysse, H\'ector Gil-Mar\'in, Ely D. Kovetz - - - JEM-EUSO Collaboration contributions to the 37th International Cosmic Ray Conference - https://arxiv.org/abs/2201.12246 - arXiv:2201.12246v2 Announce Type: replace -Abstract: Compilation of papers presented by the JEM-EUSO Collaboration at the 37th International Cosmic Ray Conference (ICRC), held on July 12-23, 2021 (online) in Berlin, Germany. - oai:arXiv.org:2201.12246v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - G. Abdellaoui, S. Abe, J. H. Adams Jr., D. Allard, G. Alonso, L. Anchordoqui, A. Anzalone, E. Arnone, K. Asano, R. Attallah, H. Attoui, M. Ave Pernas, M. Bagheri, J. Bal\'az, M. Bakiri, D. Barghini, S. Bartocci, M. Battisti, J. Bayer, B. Beldjilali, T. Belenguer, N. Belkhalfa, R. Bellotti, A. A. Belov, K. Benmessai, M. Bertaina, P. F. Bertone, P. L. Biermann, F. Bisconti, C. Blaksley, N. Blanc, S. Blin-Bondil, P. Bobik, M. Bogomilov, K. Bolmgren, E. Bozzo, S. Briz, A. Bruno, K. S. Caballero, F. Cafagna, G. Cambi\'e, D. Campana, J-N. Capdevielle, F. Capel, A. Caramete, L. Caramete, P. Carlson, R. Caruso, M. Casolino, C. Cassardo, A. Castellina, O. Catalano, A. Cellino, K. \v{C}ern\'y, M. Chikawa, G. Chiritoi, M. J. Christl, R. Colalillo, L. Conti, G. Cotto, H. J. Crawford, R. Cremonini, A. Creusot, A. de Castro G\'onzalez, C. de la Taille, L. del Peral, A. Diaz Damian, R. Diesing, P. Dinaucourt, A. Djakonow, T. Djemil, A. Ebersoldt, T. Ebisuzaki, J. Eser, F. Fenu, S. Fern\'andez-Gonz\'alez, S. Ferrarese, G. Filippatos, W. I. Finch C. Fornaro, M. Fouka, A. Franceschi, S. Franchini, C. Fuglesang, T. Fujii, M. Fukushima, P. Galeotti, E. Garc\'ia-Ortega, D. Gardiol, G. K. Garipov, E. Gasc\'on, E. Gazda, J. Genci, A. Golzio, C. Gonz\'alez Alvarado, P. Gorodetzky, A. Green, F. Guarino, C. Gu\'epin, A. Guzm\'an, Y. Hachisu, A. Haungs, J. Hern\'andez Carretero, L. Hulett, D. Ikeda, N. Inoue, S. Inoue, F. Isgr\`o, Y. Itow, T. Jammer, S. Jeong, E. Joven, E. G. Judd, J. Jochum, F. Kajino, T. Kajino, S. Kalli, I. Kaneko, Y. Karadzhov, M. Kasztelan, K. Katahira, K. Kawai, Y. Kawasaki, A. Kedadra, H. Khales, B. A. Khrenov, Jeong-Sook Kim, Soon-Wook Kim, M. Kleifges, P. A. Klimov, D. Kolev, I. Kreykenbohm, J. F. Krizmanic, K. Kr\'olik, V. Kungel, Y. Kurihara, A. Kusenko, E. Kuznetsov, H. Lahmar, F. Lakhdari, J. Licandro, L. L\'opez Campano, F. L\'opez Mart\'inez, S. Mackovjak, M. Mahdi, D. Mand\'at, M. Manfrin, L. Marcelli, J. L. Marcos, W. Marsza{\l}, Y. Mart\'in, O. Martinez, K. Mase, R. Matev, J. N. Matthews, N. Mebarki, G. Medina-Tanco, A. Menshikov, A. Merino, M. Mese, J. Meseguer, S. S. Meyer, J. Mimouni, H. Miyamoto, Y. Mizumoto, A. Monaco, J. A. Morales de los R\'ios, M. Mastafa, S. Nagataki, S. Naitamor, T. Napolitano, J. M. Nachtman A. Neronov, K. Nomoto, T. Nonaka, T. Ogawa, S. Ogio, H. Ohmori, A. V. Olinto, Y. Onel G. Osteria, A. N. Otte, A. Pagliaro, W. Painter, M. I. Panasyuk, B. Panico, E. Parizot, I. H. Park, B. Pastircak, T. Paul, M. Pech, I. P\'erez-Grande, F. Perfetto, T. Peter, P. Picozza, S. Pindado, L. W. Piotrowski, S. Piraino, Z. Plebaniak, A. Pollini, E. M. Popescu, R. Prevete, G. Pr\'ev\^ot, H. Prieto, M. Przybylak, G. Puehlhofer, M. Putis, P. Reardon, M. H. Reno, M. Reyes, M. Ricci, M. D. Rodr\'iguez Fr\'ias, O. F. Romero Matamala, F. Ronga, M. D. Sabau, G. Sacc\'a, G. S\'aez Cano, H. Sagawa, Z. Sahnoune, A. Saito, N. Sakaki, H. Salazar, J. C. Sanchez Balanzar, J. L. S\'anchez, A. Santangelo, A. Sanz-Andr\'es, M. Sanz Palomino, O. A. Saprykin, F. Sarazin, M. Sato, A. Scagliola, T. Schanz, H. Schieler, P. Schov\'anek, V. Scotti, M. Serra, S. A. Sharakin, H. M. Shimizu, K. Shinozaki, J. F. Soriano, A. Sotgiu, I. Stan, I. Strharsk\'y, N. Sugiyama, D. Supanitsky, M. Suzuki, J. Szabelski, N. Tajima, T. Tajima, Y. Takahashi, M. Takeda, Y. Takizawa, M. C. Talai, Y. Tameda, C. Tenzer, S. B. Thomas, O. Tibolla, L. G. Tkachev, T. Tomida, N. Tone, S. Toscano, M. Tra\"iche, Y. Tsunesada, K. Tsuno, S. Turriziani, Y. Uchihori, O. Vaduvescu, J. F. Vald\'es-Galicia, P. Vallania, L. Valore, G. Vankova-Kirilova, T. M. Venters, C. Vigorito, L. Villase\~nor, B. Vlcek, P. von Ballmoos, M. Vrabel, S. Wada, J. Watanabe, J. Watts Jr., R. Weigand Mu\~noz, A. Weindl, L. Wiencke, M. Wille, J. Wilms, D. Winn T. Yamamoto, J. Yang, H. Yano, I. V. Yashin, D. Yonetoku, S. Yoshida, R. Young, I. S. Zgura, M. Yu. Zotov, A. Zuccaro Marchi - - - JEM-EUSO Collaboration contributions to the 38th International Cosmic Ray Conference - https://arxiv.org/abs/2312.08204 - arXiv:2312.08204v2 Announce Type: replace -Abstract: This is a collection of papers presented by the JEM-EUSO Collaboration at the 38th International Cosmic Ray Conference (Nagoya, Japan, July 26-August 3, 2023) - oai:arXiv.org:2312.08204v2 - astro-ph.HE - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - S. Abe, J. H. Adams Jr., D. Allard, P. Alldredge, R. Aloisio, L. Anchordoqui, A. Anzalone, E. Arnone, M. Bagheri, B. Baret, D. Barghini, M. Battisti, R. Bellotti, A. A. Belov, M. Bertaina, P. F. Bertone, M. Bianciotto, F. Bisconti, C. Blaksley, S. Blin-Bondil, K. Bolmgren, S. Briz, J. Burton, F. Cafagna, G. Cambi\`e, D. Campana, F. Capel, R. Caruso, M. Casolino, C. Cassardo, A. Castellina, K. \v{C}ern\'y, M. J. Christl, R. Colalillo, L. Conti, G. Cotto, H. J. Crawford, R. Cremonini, A. Creusot, A. Cummings, A. de Castro G\'onzalez, C. de la Taille, R. Diesing, P. Dinaucourt, A. Di Nola, T. Ebisuzaki, J. Eser, F. Fenu, S. Ferrarese, G. Filippatos, W. W. Finch, F. Flaminio, C. Fornaro, D. Fuehne, C. Fuglesang, M. Fukushima, S. Gadamsetty, D. Gardiol, G. K. Garipov, E. Gazda, A. Golzio, F. Guarino, C. Gu\'epin, A. Haungs, T. Heibges, F. Isgr\`o, E. G. Judd, F. Kajino, I. Kaneko, S. -W. Kim, P. A. Klimov, J. F. Krizmanic, V. Kungel, E. Kuznetsov, F. L\'opez Mart\'inez, D. Mand\'at, M. Manfrin, A. Marcelli, L. Marcelli, W. Marsza{\l}, J. N. Matthews, M. Mese, S. S. Meyer, J. Mimouni, H. Miyamoto, Y. Mizumoto, A. Monaco, S. Nagataki, J. M. Nachtman, D. Naumov, A. Neronov, T. Nonaka, T. Ogawa, S. Ogio, H. Ohmori, A. V. Olinto, Y. Onel, G. Osteria, A. N. Otte, A. Pagliaro, B. Panico, E. Parizot, I. H. Park, T. Paul, M. Pech, F. Perfetto, P. Picozza, L. W. Piotrowski, Z. Plebaniak, J. Posligua, M. Potts, R. Prevete, G. Pr\'ev\^ot, M. Przybylak, E. Reali, P. Reardon, M. H. Reno, M. Ricci, O. F. Romero Matamala, G. Romoli, H. Sagawa, N. Sakaki, O. A. Saprykin, F. Sarazin, M. Sato, P. Schov\'anek, V. Scotti, S. Selmane, S. A. Sharakin, K. Shinozaki, S. Stepanoff, J. F. Soriano, J. Szabelski, N. Tajima, T. Tajima, Y. Takahashi, M. Takeda, Y. Takizawa, S. B. Thomas, L. G. Tkachev, T. Tomida, S. Toscano, M. Tra\"iche, D. Trofimov, K. Tsuno, P. Vallania, L. Valore, T. M. Venters, C. Vigorito, M. Vr\'abel, S. Wada, J. Watts Jr., L. Wiencke, D. Winn, H. Wistrand, I. V. Yashin, R. Young, M. Yu. Zotov - - - JADES: Rest-frame UV-to-NIR Size Evolution of Massive Quiescent Galaxies from Redshift z=5 to z=0.5 - https://arxiv.org/abs/2401.00934 - arXiv:2401.00934v2 Announce Type: replace -Abstract: We present the UV-to-NIR size evolution of a sample of 161 quiescent galaxies (QGs) with $M_*>10^{10}M_\odot$ over $0.5<z<5$. With deep multi-band NIRCam images in GOODS-South from JADES, we measure the effective radii ($R_e$) of the galaxies at rest-frame 0.3, 0.5 and 1$\mu m$. On average, QGs are 45% (15%) more compact at rest-frame 1$\mu m$ than they are at 0.3$\mu m$ (0.5$\mu m$). Regardless of wavelengths, the $R_e$ of QGs strongly evolves with redshift, and this evolution depends on stellar mass. For lower-mass QGs with $M_*=10^{10}-10^{10.6}M_\odot$, the evolution follows $R_e\sim(1+z)^{-1.1}$, whereas it becomes steeper, following $R_e\sim(1+z)^{-1.7}$, for higher-mass QGs with $M_*>10^{10.6}M_\odot$. To constrain the physical mechanisms driving the apparent size evolution, we study the relationship between $R_e$ and the formation redshift ($z_{form}$) of QGs. For lower-mass QGs, this relationship is broadly consistent with $R_e\sim(1+z_{form})^{-1}$, in line with the expectation of the progenitor effect. For higher-mass QGs, the relationship between $R_e$ and $z_{form}$ depends on stellar age. Older QGs have a steeper relationship between $R_e$ and $z_{form}$ than that expected from the progenitor effect alone, suggesting that mergers and/or post-quenching continuous gas accretion drive additional size growth in very massive systems. We find that the $z>3$ QGs in our sample are very compact, with mass surface densities $\Sigma_e\gtrsim10^{10} M_\odot/\rm{kpc}^2$, and their $R_e$ are possibly even smaller than anticipated from the size evolution measured for lower-redshift QGs. Finally, we take a close look at the structure of GS-9209, one of the earliest confirmed massive QGs at $z_{spec}\sim4.7$. From UV to NIR, GS-9209 becomes increasingly compact, and its light profile becomes more spheroidal, showing that the color gradient is already present in this earliest massive QG. - oai:arXiv.org:2401.00934v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Zhiyuan Ji, Christina C. Williams, Katherine A. Suess, Sandro Tacchella, Benjamin D. Johnson, Brant Robertson, Stacey Alberts, William M. Baker, Stefi Baum, Rachana Bhatawdekar, Nina Bonaventura, Kristan Boyett, Andrew J. Bunker, Stefano Carniani, Stephane Charlot, Zuyi Chen, Jacopo Chevallard, Emma Curtis-Lake, Francesco D'Eugenio, Anna de Graaff, Christa DeCoursey, Eiichi Egami, Daniel J. Eisenstein, Kevin Hainline, Ryan Hausen, Jakob M. Helton, Tobias J. Looser, Jianwei Lyu, Roberto Maiolino, Michael V. Maseda, Erica Nelson, George Rieke, Marcia Rieke, Hans-Walter Rix, Lester Sandles, Fengwu Sun, Hannah \"Ubler, Christopher N. A. Willmer, Chris Willott, Joris Witstok - - - On the importance of geometry in exoplanet irradiation : Implications for the day-night contrast - https://arxiv.org/abs/2406.15021 - arXiv:2406.15021v2 Announce Type: replace -Abstract: The irradiance received by a spherical body or a planet close to a spherically symmetric source does not follow the point-sized source approximation and the inverse-square variation of irradiation if spherical symmetry is broken. In the penumbral zones of the planet, spherical symmetry of the star reduces to an axial symmetry. Our work aims to put forward a fundamental explanation, using energy conservation, to determine the variation of irradiance in the penumbral zone on a close-in planet where the point-sized source approximation fails. Consequently, we propose a numerical model that accurately predicts the irradiance within the boundaries of the penumbral zone and the fully-illuminated zone. Our analysis also corrects a previous study on exoplanet irradiation that violates energy conservation. We find that night-side illumination partially explains the observed night-side temperatures on the planets considered; this reduces reliance on heat transport models to explain the night-side temperature for the few exemplar rocky close-in planets, namely K2-141 b, 55 Cancri e, TOI-561 b, TOI-431 b, and Kepler-10 b, that are discussed in this work. We provide improved day-night contrast temperatures, considering an airless scenario, and highlight the need for revisiting the heat transport models associated with atmospheric modelling of planets where the night-side illumination is significant. - oai:arXiv.org:2406.15021v2 - astro-ph.EP - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.3847/1538-4357/ae29ea - Mradumay Sadh, Lorenzo Gavassino - - - Cosmoglobe DR2. III. Improved modelling of zodiacal light with COBE-DIRBE through global Bayesian analysis - https://arxiv.org/abs/2408.11004 - arXiv:2408.11004v2 Announce Type: replace -Abstract: We present an improved zodiacal light (ZL) model for COBE-DIRBE derived through global Bayesian analysis within the Cosmoglobe Data Release 2 framework. The parametric form of the ZL model is inspired by the original DIRBE model by Kelsall et al. (K98), but the specific best-fit parameter values are re-derived using the combination of DIRBE Calibrated Individual Observations, Planck HFI sky maps, and WISE and Gaia compact object catalogs. Furthermore, the ZL parameters are fitted jointly with astrophysical parameters, such as thermal dust and starlight emission, and the new model takes into account excess radiation that appears stationary in solar-centric coordinates as reported in a companion paper. The relative differences between the predicted signals from K98 and our new model are $\lesssim 3\%$ in the 12 and 25 $\mu$m channels over the full sky. The zero-levels of the cleaned DR2 maps are lower than those of the K98 ZL Subtracted Mission Average maps by $\sim 30$ kJy/sr at 1.25--3.5 $\mu$m, which is larger than the entire predicted contribution from high-redshift galaxies to the Cosmic Infrared Background at the same wavelengths. At high Galactic latitudes, the total RMS of each DR2 map is lower than the corresponding DIRBE ZSMA map of $\sim$ 80 \% at wavelengths 4.9--25 $\mu\mathrm{m}$. Still, obvious ZL residuals can be seen in several of the DR2 maps, and further work is required to mitigate these. Joint analysis with high-resolution full-sky surveys such as AKARI, IRAS, Planck HFI, and SPHEREx will be essential both to break key degeneracies in the current model and to determine whether the reported solar-centric excess radiation has a ZL or instrumental origin. Thus, while the results presented in this paper do redefine the state-of-the-art for DIRBE modelling, it also only represents the first among many steps toward a future optimal Bayesian ZL model. (abridged) - oai:arXiv.org:2408.11004v2 - astro-ph.CO - astro-ph.EP - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - M. San, A. Bonato, M. Galloway, E. Gjerl{\o}w, D. J. Watts, R. Aurvik, A. Basyrov, L. A. Bianchi, M. Brilenkov, H. K. Eriksen, U. Fuskeland, K. A. Glasscock, L. T. Hergt, D. Herman, J. G. S. Lunde, A. I. Silva Martins, D. Sponseller, N. -O. Stutzer, R. M. Sullivan, H. Thommesen, V. Vikenes, I. K. Wehus, L. Zapelli - - - The compact object of HESS J1731-347 and its implication on neutron star matter - https://arxiv.org/abs/2408.15220 - arXiv:2408.15220v2 Announce Type: replace -Abstract: In this work, we investigate the impact of the possibility of a small, subsolar mass compact star, such as the recently reported central compact object of HESS J1731-347, on the equation of state (EOS) of neutron stars. We have used a hybrid approach to the nuclear EOS developed recently where the matter around nuclear saturation density is described by a parametric expansion in terms of nuclear empirical parameters and represented in an agnostic way at higher density using piecewise polytropes. We have incorporated the inputs provided by the latest neutron skin measurement experiments from PREX-II and CREX, simultaneous mass-radius measurements of pulsars PSR J0030+0451 and PSR J0740+6620, and the gravitational wave events GW170817 and GW190425. The main results of the study show the effect of HESS J1731-347 on the nuclear parameters and neutron star observables. Our analysis yields the slope of symmetry energy $L=45.71^{+38.18}_{-22.11}$ MeV, the radius of a $1.4 M_\odot$ star, $R_{1.4}=12.18^{+0.71}_{-0.88}$ km, and the maximum mass of a static star, $M_{\rm max}= 2.14^{+0.26}_{-0.17} M_\odot$ within $90\%$ confidence interval, respectively. - oai:arXiv.org:2408.15220v2 - astro-ph.HE - nucl-th - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Prasanta Char, Bhaskar Biswas - - - Halo Spin Depends on The Distance to Large-scale Filament - https://arxiv.org/abs/2411.11443 - arXiv:2411.11443v2 Announce Type: replace -Abstract: We employ a semi-analytical methodology to estimate the dark matter halo spin of HI gas-rich galaxies in the Arecibo Legacy Fast Alfa Survey and investigate the relationship between halo spin and the proximity of galaxies to large-scale filaments. We exclude galaxies with low HI signal-to-noise ratios, those potentially influenced by velocity dispersions, and those affiliated with galaxy clusters/groups. Additionally, we apply a mass-weighting technique to ensure consistent mass distribution across galaxy samples at varying distances from filaments. Our analysis reveals, for the first time, a subtle yet statistically significant correlation between halo spin and filament distance in observational data, indicating higher spins closer to filaments. This suggests that the tidal forces exerted by filaments may impact the spin of dark matter halos. - oai:arXiv.org:2411.11443v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Shihong Liu, Yu Rong - - - The non-linear dynamics of axion inflation: a detailed lattice study - https://arxiv.org/abs/2411.16368 - arXiv:2411.16368v2 Announce Type: replace -Abstract: We study in detail the fully inhomogeneous non-linear dynamics of axion inflation, identifying three regimes: weak-, mild-, and strong-backreaction, depending on the duration of inflation. We use lattice techniques that explicitly preserve gauge invariance and shift symmetry, and which we validate against other computational methods of the linear dynamics and of the homogeneous backreaction regime. Notably, we demonstrate that the latter fails to accurately describe the truly local dynamics of strong backreaction. We investigate the convergence of simulations of local backreaction, determining the requirements to achieve an accurate description of the dynamics, and providing useful parametrizations of the delay of the end of inflation. Additionally, we identify key features emerging from a proper local treatment of strong backreaction: the dominance of magnetic energy against the electric counterpart, the excitation of the longitudinal mode, and the generation of a scale-dependent chiral (im)balance. Our results underscore the necessity to accurately capture the local nature of the non-linear dynamics of the system, in order to correctly assess phenomenological predictions, such as e.g. the production of gravitational waves and primordial black holes. - oai:arXiv.org:2411.16368v2 - astro-ph.CO - hep-lat - hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/PhysRevD.111.063545 - Daniel G. Figueroa, Joanes Lizarraga, Nicol\'as Loayza, Ander Urio, Jon Urrestilla - - - Bumblebee cosmology: Tests using distance- and time-redshift probes - https://arxiv.org/abs/2411.18559 - arXiv:2411.18559v3 Announce Type: replace -Abstract: In modern cosmology, the discovery of the universe's accelerated expansion has significantly transformed our understanding of cosmic evolution and expansion history. The unknown properties of dark energy, the driver of this acceleration, have not only prompted extensive studies on its nature but also spurred interest in modified gravity theories that might serve as alternatives. In this paper, we adopt a bumblebee vector-tensor modified gravity theory to model the cosmic expansion history and derive predictions for the Hubble parameter. We constrain the bumblebee model parameters using observational data from established probes, including the Pantheon+ Type Ia Supernovae calibrated via the SH0ES (Supernova $H_0$ for the Equation of State) Cepheid distance ladder analysis and Baryon Acoustic Oscillations (BAO) measurements from Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), as well as recently included cosmic chronometers (CC) and gamma-ray bursts (GRBs). The Markov Chain Monte Carlo (MCMC) sampling of the Bayesian posterior distribution enables us to rigorously constrain the bumblebee models and compare them with the standard $\Lambda$CDM cosmology. We find that the bumblebee theory on its own can provide sufficiently good fits to the current observational data of distance- and time-redshift relations, suggesting its potential to explain the cosmic background dynamics. However, when compared to $\Lambda$CDM, the latter still outperforms the former according to the information criteria. We propose that further constraints from cosmological perturbation tests could impose more stringent constraints on bumblebee cosmology. - oai:arXiv.org:2411.18559v3 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Physics of the Dark Universe, 2025, Volume 50, id.102127 - Xincheng Zhu (Department of Astronomy, Tsinghua University, Beijing, China), Rui Xu (Department of Astronomy, Tsinghua University, Beijing, China), Dandan Xu (Department of Astronomy, Tsinghua University, Beijing, China) - - - Searching for New Physics in Ultradense Environment: a Review on Dark Matter Admixed Neutron Stars - https://arxiv.org/abs/2412.09381 - arXiv:2412.09381v3 Announce Type: replace -Abstract: Neutron Stars (NSs), among the densest objects in the Universe, are exceptional laboratories for investigating Dark Matter (DM) properties. Recent theoretical and observational developments have heightened interest in exploring the impact of DM on NS structure, giving rise to the concept of Dark Matter Admixed Neutron Stars (DANSs). This review examines how NSs can accumulate DM over time, potentially altering their fundamental properties. We explore leading models describing DM behavior within NSs, focusing on the effects of both bosonic and fermionic candidates on key features such as mass, radius, and tidal deformability. Additionally, we review how DM can modify the cooling and heating processes, trigger the formation of a black hole, and impact Gravitational Waves (GWs) emissions from binary systems. By synthesizing recent research, this work highlights how DANSs might produce observable signatures, offering new opportunities to probe DM properties through astrophysical phenomena. - oai:arXiv.org:2412.09381v3 - astro-ph.HE - astro-ph.CO - gr-qc - hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3390/universe11030074 - Universe 2025, 11(3), 74 - Francesco Grippa, Gaetano Lambiase, Tanmay Kumar Poddar - - - Revisiting the Galactic Winds in M82 I: the recent starburst and launch of outflow in simulations - https://arxiv.org/abs/2412.09452 - arXiv:2412.09452v4 Announce Type: replace -Abstract: We revisit the launch of the galactic outflow in M82 using hydrodynamic simulations. Employing a sink-particle module, we self-consistently resolve star formation and feedback, avoiding reliance on simplified models. We investigate the effects of stellar feedback mechanisms, gas return from star-forming clouds, and disk mass on the starburst and outflow. Our simulations generate a starburst lasting $\sim25$ Myr, peaking at 20-50 $\rm{M_{\odot},yr^{-1}}$, although the total stellar mass often exceeds M82's estimated value. The outflow develops in two stages: initially, continuous SNe form small bubbles that merge into a superbubble containing warm/hot gas and intermediate- to high-density cool filaments. After $\sim10$ Myr, the superbubble breaks out of the disk, and within $\sim15$ Myr a kpc-scale outflow forms. Cool filaments survive stellar feedback, become entrained in the wind, and stretch to hundreds of parsecs. Transport from the cool ISM is the dominant net contributor to the total mass of the cool phase in the outflow, whereas transfers from hotter phases, such as through condensation or precipitation, provide only a minor net contribution, likely offset by simultaneous transfer from the cool phase back to hotter phases. While the mass loading factor is comparable to M82, the cool gas outflow rate and velocity are lower, with velocities $\sim60\%$ below observed values; warm and hot gas are $\sim25\%$ slower. SN feedback is the primary driver, and gas return significantly influences the starburst and outflow, while other factors are secondary. Stronger clustered SN feedback is likely required to better match observations. - oai:arXiv.org:2412.09452v4 - astro-ph.GA - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tian-Rui Wang, Weishan Zhu, Xue-Fu Li, Wen-Sheng Hong, Long-Long Feng - - - Angular bispectrum of matter number counts in cosmic structures - https://arxiv.org/abs/2501.05422 - arXiv:2501.05422v3 Announce Type: replace -Abstract: The bispectrum of galaxy number counts is a key probe of large-scale structure, offering insights into the initial conditions of the Universe, the nature of gravity, and cosmological parameters. In this work, we present the first full-sky computation of the angular bispectrum in second-order perturbation theory without invoking the Limber approximation, and formulated for finite redshift bins via window functions. To our knowledge, even the Newtonian part within this setup is novel. Building on this, we also include, up to second order in perturbation theory, the dynamical general relativistic and radiation effects, together with the leading relativistic projection effects. For simplicity, we neglect tracer bias and line-of-sight integrated contributions, however note that in particular the former can be straightforwardly incorporated within our framework. We evaluate the bispectrum contributions for two redshift bins, $1.75 \leq z \leq 2.25$ and $0.55 \leq z \leq 0.65$, and compare our theoretical prediction against relativistic light-cone simulations, with line-of-sight integral effects removed so as to enable direct consistency checks. As expected, we find that the Newtonian contributions are typically one or more orders of magnitudes larger than the relativistic signal across the entire spectrum for both redshifts. At $z=2$, we find that projection and dynamical relativistic effects have comparable amplitudes on large scales; somewhat unexpectedly, however, radiation effects dominate the relativistic signal in the squeezed limit. At $z=0.6$, the expected hierarchy is recovered, though dynamical corrections remain non-negligible -- only a factor of 2-3 smaller than projection effects. Our theoretical results agree fairly well with simulation measurements for the total bispectrum. To facilitate future applications and reproducibility, we make the corresponding code publicly available. - oai:arXiv.org:2501.05422v3 - astro-ph.CO - gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Thomas Montandon, Enea Di Dio, Cornelius Rampf, Julian Adamek - - - Impact of multi-messenger spectral modelling on blazar-neutrino associations - https://arxiv.org/abs/2503.04632 - arXiv:2503.04632v2 Announce Type: replace -Abstract: Blazars are interesting source candidates for astrophysical neutrino emission. Multi-messenger lepto-hadronic models based on proton-photon (p-gamma) interactions result in predictions for the neutrino spectra (''p-gamma spectra'') which are typically strongly peaked at PeV energies. In contrast, statistical analyses looking to associate blazars and high-energy neutrinos often assume a power-law spectral shape, putting the emphasis at lower energies. We aim to examine the impact of such spectral modelling assumptions on the associations of neutrinos with blazars. We use hierarchical_nu, a Bayesian framework for point source searches, and incorporate the theoretical predictions for neutrino spectra through a dedicated spectral model and priors on the relevant parameters. Our spectral model is based on recent predictions for a selection of intermediate and high synchrotron peaked blazars that have been found to be spatially close to high-energy events detected by IceCube. We apply our model to the 10 years of publicly available muon track IceCube data aimed at point source searches, focusing on the Northern hemisphere. Out of 29 source candidates, we find five sources, including TXS 0506+056, that have an association probability $P_\mathrm{assoc} > 0.5$ to at least one event. The p-gamma spectra typically lead to a lower overall number of associated events compared to the power-law case, but retain or even enhance strong associations to high-energy events. Our results demonstrate that including more information from theoretical predictions can allow for more interpretable source-neutrino connections. - oai:arXiv.org:2503.04632v2 - astro-ph.HE - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.3847/1538-4357/ae1033 - Julian Kuhlmann, Francesca Capel - - - Galaxies in the Epoch of Reionization Are All Bark and No Bite -- Plenty of Ionizing Photons, Low Escape Fractions - https://arxiv.org/abs/2505.08870 - arXiv:2505.08870v2 Announce Type: replace -Abstract: Early results from JWST suggest that epoch-of-reionization (EoR) galaxies produce copious ionizing photons, which, if they escape efficiently, could cause reionization to occur too early. We study this problem using \jwst\ imaging and prism spectroscopy for 412 galaxies at 4.5 < z < 9.0. We fit these data simultaneously with stellar-population and nebular-emission models that include a parameter for the fraction of ionizing photons that escape the galaxy, $f_\mathrm{esc}$. We find that the ionization production efficiency, $\xi_\mathrm{ion}$ = Q(H) / L(UV), increases with redshift and decreasing UV luminosity, but shows significant scatter, $\sigma( \log \xi_\mathrm{ion})$ = 0.3 dex. The inferred escape fractions averaged over the population are low, ranging from $\langle f_\mathrm{esc} \rangle$ = $2.6\pm 1.4$\% at 6 < z < 9 to $6.5\pm 2.2$\% at 4.5 < z < 6 with weak or no indication of evolution with redshift. This implies that in our models most of the ionizing photons need to be absorbed to account for the nebular emission. We compute the impact of our results on reionization, including the distributions for $\xi_\mathrm{ion}$ and $f_\mathrm{esc}$, and the evolution and uncertainty of the UV luminosity function. Considering galaxies brighter than M(UV) < -16 mag, we would produce an IGM hydrogen-ionized fraction of $x_e = 0.5$ at 5.3 < z < 5.8, possibly too late compared to constraints from from QSO sightlines. Including fainter galaxies, M(UV) < -14 mag, we obtain $x_e = 0.5$ at 6.0 < z < 8.1, fully consistent with QSO and CMB data. This implies that EoR galaxies produce plenty of ionizing photons, but these do not efficiently escape. This may be a result of high gas column densities combined with burstier star-formation histories, which limit the time massive stars are able to clear channels through the gas for ionizing photons to escape. - oai:arXiv.org:2505.08870v2 - astro-ph.GA - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Casey Papovich (Texas A & M University), Justin W. Cole (Texas A & M University), Weida Hu (Texas A & M University), Steven L. Finkelstein (University of Texas at Austin), Lu Shen (Texas A & M University), Pablo Arrabal Haro (NASA-Goddard), Ricardo O. Amor\'in (Instituto de Astrofiscia de Andalucia), Bren Backhaus (Kansas), Micaela B. Bagley (University of Texas at Austin, Kansas), Rachana Bhatawdekar (European Space Agency), Antonello Calabr\'o (INAF Osservatorio Astronomico di Roma), Adam C. Carnall (University of Edinburgh), Nikko Cleri (Penn State University), Emanuele Daddi (Universite Paris-Saclay), Mark Dickinson (NSF's NOIRlab), Norman Grogin (STScI), Benne W. Holwerda (University of Louisville), Anne E. Jaskot (Williams College), Anton M. Koekemoer (STScI), Mario Llerena (INAF Osservatorio Astronomico di Roma), Ray A. Lucas (STScI), Sara Mascia (Institute of Science and Technology Austria), Fabio Pacucci (Harvard CfA), Laura Pentericci (INAF Osservatorio Astronomico di Roma), Pablo G. P\'erez-Gonz\'alez (Centro de Astrobiologica, CAB/CSIC-INTA), Nor Pirzkal (ESA/AURA STScI), Srinivasan Raghunathan (Center for AstroPhysical Surveys, National Center for Supercomputing Applications), Lisa-Marie Seill\'e (Aix Marseille Univ, CNRS, CNES, LAM), Rachel Somerville (Center for Computational Astrophysics, Flatiron Institute), L. Y. Aaron Yung (STScI) - - - A black hole in a near-pristine galaxy 700 million years after the Big Bang - https://arxiv.org/abs/2505.22567 - arXiv:2505.22567v5 Announce Type: replace -Abstract: The recent discovery of a large number of massive black holes within the first two billion years after the Big Bang, as well as their peculiar properties, have been largely unexpected based on the extrapolation of the properties of luminous quasars. These findings have prompted the development of several theoretical models for the early formation and growth of black holes, which are, however, difficult to differentiate. We report the metallicity measurement around a gravitationally lensed massive black hole at redshift 7.04 (classified as a Little Red Dot), hosted in a galaxy with very low dynamical mass. The weakness of the [OIII]5007 emission line relative to the narrow H$\beta$ emission indicates extremely low metallicity, about $4\times 10^{-3}$ solar, and even more metal poor in the surrounding few 100 pc. We argue that such properties cannot be uncommon among accreting black holes around this early cosmic epoch. Explaining such a low chemical enrichment in a system that has developed a massive black hole is challenging for most theories. Models assuming heavy black hole seeds (such as Direct Collapse Black Holes) or super-Eddington accretion scenarios struggle to explain the observations, although they can potentially reproduce the observed properties in some cases. Models invoking "primordial black holes" (i.e. putative black holes formed shortly after the Big Bang) may potentially explain the low chemical enrichment associated with this black hole, although this class of models also requires further developments for proper testing. - oai:arXiv.org:2505.22567v5 - astro-ph.GA - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Roberto Maiolino, Hannah Uebler, Francesco D'Eugenio, Jan Scholtz, Ignas Juodzbalis, Xihan Ji, Michele Perna, Volker Bromm, Pratika Dayal, Sophie Koudmani, Boyuan Liu, Raffaella Schneider, Debora Sijacki, Rosa Valiante, Alessandro Trinca, Saiyang Zhang, Marta Volonteri, Kohei Inayoshi, Stefano Carniani, Kimihiko Nakajima, Yuki Isobe, Joris Witstok, Gareth C. Jones, Sandro Tacchella, Santiago Arribas, Andrew Bunker, Elisa Cataldi, Stephane Charlot, Giovanni Cresci, Mirko Curti, Andrew C. Fabian, Harley Katz, Nimisha Kumari, Nicolas Laporte, Giovanni Mazzolari, Brant Robertson, Fengwu Sun, Bruno Rodriguez Del Pino, Giacomo Venturi - - - Shape Shifting Light Dark Matter Solitons - https://arxiv.org/abs/2506.01282 - arXiv:2506.01282v2 Announce Type: replace -Abstract: Dark matter consisting of a Bose--Einstein condensate (BEC) of ultra-light particles is predicted to have a soliton shape that shifts with the dark matter mass fraction in galaxies containing a centrally localized point mass (or black hole), consistent with previous numerical results and analytical approximations in both the cored self-gravitating and cusped hydrogenic limits. Solutions of the Schr\"{o}dinger-Poisson equation with baryonic coupling are here accurately represented as a sum of five Gaussians with numerically optimized amplitudes and widths, thereby facilitating galactic predictions and observational comparisons as a function of dark matter mass fraction. The results are used to derive mass, energy and velocity scaling relations as functions of soliton mass fraction, as well as to predict dark matter halo size, mass and core density in terms of observed half-light radii and velocity dispersions by invoking observationally validated approximations relating rotational velocity and velocity dispersion. Applications of the predictions, as well as challenges associated with critically testing dark matter models, are illustrated using comparisons with dwarf spheroidal (dSph) and ultra-faint dwarf (UFD) galaxy observations, which, under the present soliton-based modeling assumptions, are found to be compatible with soliton particle masses of the order of $10^{-22}$ (eV/c$^2$), with an upper bound of approximately $3\times 10^{-22}$ (eV/c$^2$). Implications of the results are discussed, including speculations regarding the role of dark matter evaporation in galactic evolution. - oai:arXiv.org:2506.01282v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Dor Ben-Amotz - - - Distinguishing Orbiting and Infalling Dark Matter Particles with Machine Learning - https://arxiv.org/abs/2506.09146 - arXiv:2506.09146v2 Announce Type: replace -Abstract: Dark matter halos are typically defined as spheres that enclose some overdensity, but these sharp, somewhat arbitrary boundaries introduce non-physical artifacts such as backsplash halos, pseudo-evolution, and an incomplete accounting of halo mass. A more physically motivated alternative is to define halos as the collection of particles that are physically orbiting within their potential well. However, existing methods to classify particles as orbiting or infalling suffer from trade-offs between accuracy, computational cost, and generalizability across cosmologies. We present an efficient, yet accurate, supervised machine learning approach using decision trees. The classification is based on only the particle radii and velocities at two epochs. Compared to detailed analysis of particle trajectories, we find that our model matches the classification of 97\% of particles. Consequently, we are able to quickly and accurately reproduce the density profiles of the orbiting and infalling components out to many virial radii. We demonstrate that our model generalizes to a significantly different cosmology that lies outside the training dataset. We make publicly available both our final model and the code to train similar models. - oai:arXiv.org:2506.09146v2 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.3847/1538-4357/ae1a76 - Ze'ev Vladimir, Calvin Osinga, Benedikt Diemer, Edgar M. Salazar, Eduardo Rozo - - - Hawking Radiation Signatures from Primordial Black Holes Transiting the Inner Solar System: Prospects for Detection - https://arxiv.org/abs/2506.14041 - arXiv:2506.14041v2 Announce Type: replace -Abstract: Primordial black holes (PBHs) arise from the collapse of density perturbations in the early universe and serve as a dark matter (DM) candidate and a probe of fundamental physics. There remains an unconstrained ``asteroid-mass'' window where PBHs of masses $10^{17} {\rm g} \lesssim M \lesssim 10^{23} {\rm g}$ could comprise up to $100\%$ of the dark matter. Current $e^{\pm}$ Hawking radiation constraints on the DM fraction of PBHs are set by comparing observed spatial- and time-integrated cosmic ray flux measurements with predicted Hawking emission fluxes from the galactic DM halo. These constraints depend on cosmic ray production and propagation models, the galactic DM density distribution, and the PBH mass function. We propose to mitigate these model dependencies by developing a new local, time-dependent Hawking radiation signature to detect low-mass PBHs transiting through the inner Solar System. We calculate transit rates for PBHs that form with initial masses $M \lesssim 5\times10^{17}\text{g}$. We then simulate time-dependent positron signals from individual PBH flybys as measured by the Alpha Magnetic Spectrometer (AMS) experiment in low-Earth orbit. We find that AMS is sensitive to PBHs with masses $M\lesssim 2\times10^{14} \, {\rm g}$ due to its lower energy threshold of $500 \, {\rm MeV}$. We demonstrate that a dataset of daily positron fluxes over the energy range $5-500 \, {\rm MeV}$, with similar levels of precision to the existing AMS data, would enable detection of PBHs drawn from present-day distributions that peak within the asteroid-mass window. Our simulations yield ${\cal O} (1)$ detectable PBH transits per year across wide regions of parameter space, which may be used to constrain PBH mass functions. This technique could be extended to detect $\gamma$-ray and X-ray Hawking emission to probe further into the asteroid-mass window. - oai:arXiv.org:2506.14041v2 - astro-ph.CO - astro-ph.HE + Single-wave solutions of the neutrino fast flavor system. Part I. Mechanical properties + https://arxiv.org/abs/2601.15372 + arXiv:2601.15372v1 Announce Type: cross +Abstract: A dense neutrino plasma can exhibit collective flavor evolution caused by neutrino--neutrino refraction. Recently, a new class of exact nonlinear inhomogeneous solutions was discovered: single-wave (SW) solutions of the fast flavor system. The key property is that the flavor occupation numbers remain homogeneous, whereas the field of flavor coherence varies spatially with a single wave vector. The equations of motion for this structure resemble those of a collection of classical spins, in analogy with the homogeneous slow and fast flavor cases. In contrast, the SW system is not integrable (it does not possess Gaudin invariants) so that, while two-beam pendulum solutions are inevitable, they do not extend to a multi-angle system. We develop a taxonomy of all known nonlinear collective flavor solutions, explaining the overlap between categories and their differences. + oai:arXiv.org:2601.15372v1 hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/9jyp-24sw - Physical Review D 112 (2025): 103007 - Alexandra P. Klipfel, Peter Fisher, David I. Kaiser - - - Euclid: An emulator for baryonic effects on the matter bispectrum - https://arxiv.org/abs/2506.18974 - arXiv:2506.18974v2 Announce Type: replace -Abstract: Understanding the impact of baryonic processes such as star formation and active galactic nuclei (AGN) feedback on matter clustering is crucial to ensure precise and unbiased cosmological inference. Most theoretical models of baryonic effects to date focus on two-point statistics, neglecting higher-order contributions. This work develops a fast and accurate emulator for baryonic effects on the matter bispectrum, a key non-Gaussian statistic in the nonlinear regime. We employ high-resolution $N$-body simulations from the BACCO suite and apply a combination of cutting-edge techniques such as cosmology scaling and baryonification to efficiently span a large cosmological and astrophysical parameter space. A deep neural network is trained to emulate baryonic effects on the matter bispectrum measured in simulations, capturing modifications across various scales and redshifts relevant to Euclid. We validate the emulator accuracy and robustness using an analysis of \Euclid mock data, employing predictions from the state-of-the-art FLAMINGO hydrodynamical simulations. The emulator reproduces baryonic suppression in the bispectrum to better than 2$\%$ for the $68\%$ percentile across most triangle configurations for $k \in [0.01, 20]\,\mathrm{i}h\mathrm{Mpc}^{-1}$ and ensures consistency between cosmological posteriors inferred from second- and third-order weak lensing statistics. These results demonstrate that our emulator meets the high-precision requirements of the Euclid mission for at least the first data release and provides reliable forecasts of the cosmological information contained in the small-scale matter bispectrum. This underscores the potential of emulation techniques to bridge the gap between complex baryonic physics and observational data, maximising the scientific output of Euclid. - oai:arXiv.org:2506.18974v2 astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1051/0004-6361/202556061 - Volume 705, 2026, A170 - P. A. Burger, G. Aric\`o, L. Linke, R. E. Angulo, J. C. Broxterman, J. Schaye, M. Schaller, M. Zennaro, A. Halder, L. Porth, S. Heydenreich, M. J. Hudson, A. Amara, S. Andreon, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, A. Biviano, E. Branchini, M. Brescia, S. Camera, V. Capobianco, C. Carbone, V. F. Cardone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, A. Da Silva, H. Degaudenzi, S. de la Torre, G. De Lucia, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, P. Fosalba, N. Fourmanoit, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keih\"anen, S. Kermiche, M. Kilbinger, B. Kubik, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. Massey, E. Medinaceli, S. Mei, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, C. Neissner, S. -M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, F. Raison, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, A. G. S\'anchez, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, E. Sefusatti, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, A. Spurio Mancini, L. Stanco, J. Steinwagner, P. Tallada-Cresp\'i, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, E. Zucca, C. Burigana, L. Gabarra, A. Pezzotta, V. Scottez, M. Viel - - - An Accretion Flare Interpretation for the Ultra-High-Energy Neutrino Event KM3-230213A - https://arxiv.org/abs/2506.21111 - arXiv:2506.21111v2 Announce Type: replace -Abstract: We study the origin of the ultra-high-energy (UHE) neutrino event KM3-230213A detected by KM3NeT, focusing on MRC 0614-083 which has been pinpointed as the closest blazar to the neutrino localization exhibiting variable multi-wavelength emission. A joint interpretation of the optical, infrared, and X-ray light curves suggests that MRC 0614-083 has undergone a super-Eddington accretion flare accompanied by efficient proton acceleration. That flare has initiated a delayed infrared echo within the surrounding dust torus, which serves as a target for photomeson ($p\gamma$) interactions such that a self-consistent picture emerges that complements the blazar jet scenario: the predicted UHE neutrino flux is at the level expected from joint $E^{-2}$ fit with the IceCube measurements at lower energies, the variable nature of the event alleviates the tension with IceCube limits, and the accompanying electromagnetic cascade describes the X-ray flare around the neutrino detection time. Since a key remaining uncertainty is the unknown redshift of the source, we strongly encourage optical/ultraviolet spectroscopic measurements to determine its redshift. - oai:arXiv.org:2506.21111v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Chengchao Yuan, Leonard Pfeiffer, Walter Winter, Jose Maria Sanchez Zaballa, Sara Buson, Federico Testagrossa, Alessandra Azzollini - - - REBELS-MOSFIRE: Weak CIII] Emission is Typical Among Extremely UV-bright, Massive Galaxies at $z\sim7$ - https://arxiv.org/abs/2506.21674 - arXiv:2506.21674v2 Announce Type: replace -Abstract: We present Keck/MOSFIRE H-band spectroscopic measurements covering the [CIII]1907, CIII]1909 doublet for a sample of 8 z~7 spectroscopically-confirmed star-forming galaxies drawn from the Reionization Era Bright Emission Line Survey (REBELS). This REBELS-MOSFIRE sample is notable for its bright median UV luminosity (Muv=-22.5 AB) and large median stellar mass (log(Mstar/Msun)=9.2). Although three sources show tentative evidence of a CIII] detection, we obtain no confident detections for any of the 8 REBELS-MOSFIRE sources. The median [CIII]1907+CIII]1909 3-sigma upper limit in equivalent width (EW) for the REBELS-MOSFIRE sample is 6.5 AA, and a stack of their H-band MOSFIRE spectra yields a non-detection with an associated 3-sigma upper limit of 2.6 AA. These upper limits fall significantly below the CIII] EW measured in a composite spectrum of representative z~7 star-forming galaxies, as well as those measured for notable early star-forming galaxies such as GN-z11, GHZ2, GS-z12, and RXCJ2248-ID. The lack of strong CIII] emission can be understood within the context of the stellar populations of the REBELS galaxies, as well as the ionization conditions and gas-phase metallicity implied by rest-frame optical spectroscopic properties ([OIII]+Hb EWs, and [OIII]5007/[OII]3727 and [NeIII]3869/[OII]3727 line ratios). The REBELS-MOSFIRE sample represents the higher-mass, higher-metallicity, lower-excitation tail of the z~7 galaxy population, whose ionizing properties must be fully characterized to constrain the role of star-forming galaxies during cosmic reionization. - oai:arXiv.org:2506.21674v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ryan Endsley, Alice E. Shapley, Michael W. Topping, Daniel P. Stark, Rychard J. Bouwens, Lucie E. Rowland, Laura Sommovigo, Hiddo S. B. Algera, Manuel Aravena, Rebecca A. A. Bowler, Elisabete da Cunha, Ilse de Looze, Andrea Ferrara, Rebecca Fisher, Valentino Gonz\'alez, Hanae Inami, Themiya Nanayakkara, Sander Schouws, Mengtao Tang - - - Multimessenger Emission from Very-High-Energy Black Hole-Jet Systems in the Milky Way - https://arxiv.org/abs/2506.22550 - arXiv:2506.22550v2 Announce Type: replace -Abstract: Microquasars, compact binary systems with an accreting stellar-mass black hole or neutron star, are promising candidates for high-energy particle acceleration. Recently, the LHAASO collaboration reported on the detection of $>100$ TeV $\gamma$-ray emission from five microquasars, suggesting that these sources are efficient particle accelerators. In microquasars, high-energy $\gamma$-rays can be produced in large-scale jets or winds. In this work, we explore the X-ray, $\gamma$-ray and neutrino emission from SS 433, V4641 Sgr and GRS 1905+105. We consider leptonic and hadronic scenarios to explain the spectra observed by LHAASO and other high-energy $\gamma$-ray detectors. We estimate the neutrino flux associated with the hadronic component and investigate the detectability of neutrinos from these sources in current and future neutrino telescopes. We find that among the three sources, V4641 Sgr has the best prospects of observation with a combined next-generation neutrino telescopes. - oai:arXiv.org:2506.22550v2 - astro-ph.HE - hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1016/j.jheap.2025.100538 - JHEAP 51:100538 (2025) - Jose Carpio, Ali Kheirandish, Bing Zhang - - - The diffuse supernova neutrino background: an update with modern population synthesis and core-collapse simulations - https://arxiv.org/abs/2506.22699 - arXiv:2506.22699v2 Announce Type: replace -Abstract: We present a new, state-of-the-art computation of the Diffuse Supernova Neutrino Background (DSNB), where we use neutrino spectra from multi-dimensional, multi-second core collapse supernova simulations - including both neutron-star and black-hole forming collapses - and binary evolution effects from modern population synthesis codes. Large sets of numerical results are processed and connected in a consistent manner, using two key quantities: the mass of the star's Carbon-Oxygen (CO) core at an advanced pre-collapse stage - which depends on binary evolution effects - and the compactness parameter, which is the main descriptor of the post-collapse neutrino emission. The method enables us to model the neutrino emission of a very diverse, binary-affected population of stars, which cannot unambiguously be mapped in detail by existing core collapse simulations. We find that including black hole-forming collapses enhances the DSNB by up to 50% at energies greater than 30-40 MeV. Binary evolution effects can change the total rate of collapses and generate a sub-population of high core mass stars that are stronger neutrino emitters. However, the net effect on the DSNB is moderate - up to a 15% increase in flux - due to the rarity of these super-massive cores and to the relatively modest dependence of the neutrino emission on the CO core mass. The methodology presented here is suitable for extensions and generalizations, and therefore it lays the foundation for modern treatments of the DSNB. - oai:arXiv.org:2506.22699v2 astro-ph.HE - hep-ph - nucl-th - Wed, 21 Jan 2026 00:00:00 -0500 - replace + Fri, 23 Jan 2026 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/yt5x-cbnp - Cecilia Lunardini, Tomoya Takiwaki, Tomoya Kinugawa, Shunsaku Horiuchi, Kei Kotake + Damiano F. G. Fiorillo, Georg G. Raffelt - Gravitational lensing rarely produces high-mass outliers to the compact binary population - https://arxiv.org/abs/2507.07964 - arXiv:2507.07964v2 Announce Type: replace -Abstract: All gravitational-wave signals are inevitably gravitationally lensed by intervening matter as they propagate through the Universe. When a gravitational-wave signal is magnified, it \emph{appears} to have originated from a closer, more massive system. Thus, high-mass outliers to the gravitational-wave source population are often proposed as natural candidates for strongly lensed events. However, when using a data-driven method for identifying population outliers, we find that high-mass outliers are not necessarily strongly lensed, nor will the majority of strongly-lensed signals appear as high-mass outliers. This is both because statistical fluctuations produce a larger effect on observed binary parameters than does lensing magnification, and because lensing-induced outliers must originate from intrinsically high-mass sources, which are rare. Thus, the appearance of a single lensing-induced outlier implies the existence of many other lensed events within the catalog. We additionally show that it is possible to constrain the strong lensing optical depth, which is a fundamental quantity of our Universe, with the detection or absence of high-mass outliers. However, constraints using the latest gravitational-wave catalog are weak$\unicode{x2014}$we obtain an upper limit on the optical depth of sources at redshift $1$ magnified by a factor of $5$ or more of $\tau(\mu\geq5,z=1)\leq 0.035 \unicode{x2014}$and future observing runs will not make an outlier-based method competitive with other probes of the optical depth. However, the full inferred population of compact binaries may be more informative of the distribution of lenses in the Universe, opening a unique opportunity to access the high-redshift Universe and constrain cosmic structures. - oai:arXiv.org:2507.07964v2 - astro-ph.HE - astro-ph.CO + Compact Stars Sourced by Dark Matter Halos and Their Frozen States + https://arxiv.org/abs/2601.15415 + arXiv:2601.15415v1 Announce Type: cross +Abstract: Inspired by regular black holes (RBHs) sourced by dark matter halos, we generalize the anisotropic energy-momentum tensor by relaxing the $P_r = -\rho$ condition between radial pressure and density. We demonstrate that while RBHs are a unique special case, a broader class of relations yields horizonless compact stars. Under specific parameter limits, these objects approach a ``frozen state," mimicking black hole features without an event horizon. These compact star solutions could satisfy weak energy conditions and provide a robust mechanism for dark matter-sourced black hole mimickers. + oai:arXiv.org:2601.15415v1 gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 - replace + astro-ph.HE + hep-th + Fri, 23 Jan 2026 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Amanda M. Farah, Jose Mar\'ia Ezquiaga, Maya Fishbach, Daniel E. Holz - - - MIRACLE II: Unveiling the multi-phase gas interplay in the circumnuclear region of NGC 1365 via multi-cloud modeling - https://arxiv.org/abs/2507.08077 - arXiv:2507.08077v4 Announce Type: replace -Abstract: We present a multi-phase study of the gas in the circumnuclear region (~1.1x1.0 kpc^2) of the nearby Seyfert 1.8 galaxy NGC 1365, observed in the context of the Mid-IR Activity of Circumnuclear Line Emission (MIRACLE) program. We combined spatially resolved spectroscopic observations from JWST/MIRI, VLT/MUSE, and ALMA to investigate the ionized atomic gas and the warm and cold molecular phases. - MIRI data revealed over 40 mid-IR emission lines from ionized and warm molecular gas. Moment maps show that both cold and warm molecular gas follow the rotation of the stellar disk along the circumnuclear ring. The ionized gas displays flux and kinematic patterns that depend on ionization potential (IP): low-IP species (<25 eV) trace the disk, while higher-IP lines (up to ~120 eV) trace outflowing material. - The [O III]5700 and [Ne V]14 lines both trace the southeast nuclear outflow cone. Additionally, [Ne V]14 detects the northwest counter-cone, obscured in the optical and thus invisible in [O III]5700. Mid-IR diagnostics, unlike optical ones, clearly reveal the AGN as the primary ionization source in the nucleus. Emission from high-IP species is spatially coincident with the ionization cones and not with star-forming regions. - Using the [Ne V]24/[Ne V]14 ratio, we derive an electron density of (750+-440) cm^(-3), in agreement with values from the [S II] optical doublet. - For the first time, we apply a fully self-consistent approach combining advanced photoionization and kinematic models (HOMERUN+MOKA3D) to constrain intrinsic outflow properties, overcoming the limitations of simplified classical methods. Exploiting the synergy of JWST/MIRI and VLT/MUSE, HOMERUN reproduces fluxes of over 60 emission lines from optical to mid-IR, disentangling AGN and star formation contributions and yielding robust estimates of outflow mass, geometry, and energetics. - oai:arXiv.org:2507.08077v4 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - M. Ceci, C. Marconcini, A. Marconi, A. Feltre, I. Lamperti, F. Belfiore, E. Bertola, C. Bracci, S. Carniani, E. Cataldi, G. Cresci, Q. D'Amato, J. Fritz, M. Ginolfi, E. Hatziminaoglou, M. Hirschmann, M. Mingozzi, B. Moreschini, F. Mannucci, G. Sabatini, F. Salvestrini, M. Scialpi, G. Tozzi, L. Ulivi, G. Venturi, A. Vidal-Garc\'ia, C. Vignali, M. V. Zanchettin + Yuan Yue, Yong-Qiang Wang - Simulation-based inference with deep ensembles: Evaluating calibration uncertainty and detecting model misspecification - https://arxiv.org/abs/2507.13495 - arXiv:2507.13495v2 Announce Type: replace -Abstract: Simulation-Based Inference (SBI) offers a principled and flexible framework for conducting Bayesian inference in any situation where forward simulations are feasible. However, validating the accuracy and reliability of the inferred posteriors remains a persistent challenge. In this work, we point out a simple diagnostic approach rooted in ensemble learning methods to assess the internal consistency of SBI outputs that does not require access to the true posterior. By training multiple neural estimators under identical conditions and evaluating their pairwise Kullback-Leibler (KL) divergences, we define a consistency criterion that quantifies agreement across the ensemble. We highlight two core use cases for this framework: a) for generating a robust estimate of the systematic uncertainty in parameter reconstruction associated with the training procedure, and b) for detecting possible model misspecification when using trained estimators on real data. We also demonstrate the relationship between significant KL divergences and issues such as insufficient convergence due to, e.g., too low a simulation budget, or intrinsic variance in the training process. Overall, this ensemble-based diagnostic framework provides a lightweight, scalable, and model-agnostic tool for enhancing the trustworthiness of SBI in scientific applications. - oai:arXiv.org:2507.13495v2 + Determination of the longitude difference between Baghdad and Khwarezm using a lunar eclipse (the method of Abu Rayhan al-Biruni and Abu al-Wafa al-Buzjani) + https://arxiv.org/abs/2601.15837 + arXiv:2601.15837v1 Announce Type: cross +Abstract: This paper examines how, in the tenth century, medieval Iranian scholars Abu Rayhan al-Biruni and Abu al-Wafa al-Buzjani determined the difference in geographical longitude between the cities of Baghdad and Khwarezm through simultaneous observation of a lunar eclipse. Brief academic biographies of these scholars are presented, with emphasis on their contributions to mathematics and astronomy. The study discusses the importance of determining geographical coordinates - especially longitude - in the science of the 10th-11th centuries, provides an overview of the methods of coordinate determination available at the time, and highlights the problem of synchronizing remote observations prior to the advent of electronic communication. Particular attention is devoted to a detailed analysis of the method based on observing a lunar eclipse to simultaneously measure longitude differences: the necessary conditions and organization of the experiment, the instruments employed, the mathematical calculations, and error estimates are described. The longitude difference obtained by al-Biruni and al-Buzjani is compared with modern values. The conclusion discusses the scientific significance of this method for the history of science and astronomy. + oai:arXiv.org:2601.15837v1 + physics.hist-ph astro-ph.IM - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - James Alvey, Carlo R. Contaldi, Mauro Pieroni - - - Optical and near-infrared nebular-phase spectroscopy of SN 2024ggi: constraints on the structure of the inner ejecta, progenitor mass, and dust - https://arxiv.org/abs/2508.02656 - arXiv:2508.02656v3 Announce Type: replace -Abstract: We present optical and near-infrared (NIR) spectroscopic observations of the nearby Type II supernova SN\,2024ggi from 250 and 581 days after the explosion. Comparing the evolution of the [\ion{O}{1}] at 6300, 6363 \text{\AA} doublet normalized to the continuum with spectral models from the literature, we estimate a progenitor star zero-age main-sequence mass ($M_{\mathrm{ZAMS}}$) of $\approx 14$ M$_\odot$. This value is consistent with $M_{\mathrm{ZAMS}}$ reported in the literature from independent methodologies. The nebular spectra are used to study the structure of the inner ejecta. The broad H$\alpha$ line has a full-width at half maximum (FWHM) of $\simeq 3900$ km s$^{-1}$, with small deviations from a symmetric Gaussian profile centred at zero velocity, and the [\ion{O}{1}] doublet is blue-shifted by $\approx -940$ km s$^{-1}$. In the NIR, the nebular spectra reveal double-peaked emission features of \ion{Mg}{1} and [\ion{Fe}{2}] lines between +250 and +319 days, suggesting a bipolar distribution of intermediate mass and iron peak elements in the line-of-sight. Such a double-peaked feature in these NIR lines has not been previously reported. No corresponding asymmetries are observed in the hydrogen lines, suggesting that the asymmetry is mostly confined to intermediate mass and iron peak elements in the innermost core of the supernova ejecta. Additionally, we detect first-overtone carbon monoxide (CO) emission at 2.3,$\mu$m between 250 and 319 days, and a blueshift in the emission lines of H$\alpha$, [\ion{O}{1}], \ion{Mg}{1}], and [\ion{Fe}{2}] in the +581 day optical spectrum, consistent with dust formation in the ejecta. - oai:arXiv.org:2508.02656v3 - astro-ph.SR - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - replace + Fri, 23 Jan 2026 00:00:00 -0500 + cross http://creativecommons.org/licenses/by/4.0/ - Emilio Hueichap\'an, R\'egis Cartier, Jose L. Prieto, Carlos Contreras, Aleksandar Cikota, Thallis Pessi, Franz E. Bauer, Giuliano Pignata, Camila Cardenas, Sethulakshmi Vazhayil + Rizoi Bakhromzod - On frequentist confidence intervals in a non-Gaussian regime - https://arxiv.org/abs/2508.10633 - arXiv:2508.10633v2 Announce Type: replace -Abstract: We study frequentist confidence intervals based on graphical profile likelihoods (Wilks' theorem, likelihood integration), and the Feldman-Cousins (FC) prescription, a generalisation of the Neyman belt construction, in a setting with non-Gaussian Markov chain Monte Carlo (MCMC) posteriors. Our simplified setting allows us to recycle the MCMC chain as an input in all methods, including mock simulations underlying the FC approach. We find all methods agree to within $10 \%$ in the close to Gaussian regime, but extending methods beyond their regime of validity leads to greater discrepancies. Importantly, we recover a $\sim 2 \sigma$ shift in cosmological parameters between low and high redshift cosmic chronometer data with the FC method, but only when one fits all parameters back to the mocks. We observe that fixing parameters, a common approach in the literature, risks underestimating confidence intervals. - oai:arXiv.org:2508.10633v2 - astro-ph.CO - gr-qc + Neutrino-Induced Polarization Rotation in Active Galactic Nuclei Plasmas + https://arxiv.org/abs/2601.15910 + arXiv:2601.15910v1 Announce Type: cross +Abstract: We study parity-violating birefringence induced by an asymmetric neutrino background in plasmas associated with active galactic nuclei (AGN). We derive a directionality factor arising from the relative bulk motion between the neutrino medium and plasma, and show that it can produce an anomalous frequency dependence of the polarization-rotation angle, distinct from the $\omega^{-2}$ scaling of Faraday rotation. This anomalous scaling can occur either at the resonance plasma frequency condition $\omega \simeq \omega_p$, or when $E_\nu^{0}\simeq m_\nu \omega/\omega_p$ lies within the range of the neutrino energy spectrum. We estimate the effect for three scenarios: jets propagating through the cosmic neutrino background (C$\nu$B), jets with an internal flux of high-energy neutrinos, and accretion-disk plasma permeated by the C$\nu$B. Of the three scenarios, the latter gives the largest rotation angle $\phi_{\rm d} \sim 10^{-35}\,\mathrm{rad}$, at X-ray frequencies. Although the predicted rotation angles are below current polarimetric sensitivity, the identified spectral signatures provide a theoretical framework for probing neutrino asymmetries and AGN plasma properties independent of magnetic field models. + oai:arXiv.org:2601.15910v1 hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Shubham Barua, Shantanu Desai, Mauricio Lopez-Hernandez, Eoin \'O Colg\'ain - - - Three-Dimensional Numerical Simulations of Magnetar Crust Quakes - https://arxiv.org/abs/2508.12567 - arXiv:2508.12567v2 Announce Type: replace -Abstract: Crust quakes are frequently invoked as a mechanism to trigger sudden transients in the magnetospheres of magnetars. In this picture, a mechanical failure of the crust excites seismic motions of the magnetar surface that launch force-free waves into the magnetosphere. We first investigate this problem analytically and then perform three-dimensional numerical simulations. Our simulations follow the propagation of high-frequency magneto-elastic waves in the entire crust, and include magnetic coupling to the dipolar magnetosphere and liquid core through simplified radiation boundary conditions. We observe seismic waves bouncing between the crust-core interface and the surface with a characteristic frequency $\sim 1$~kHz, which could appear as a modulation of the magnetospheric radiation. Both the star quake and its associated magnetospheric wave emission are strongly damped on a timescale $\sim 10 \ \rm ms$ by magnetic coupling to the liquid core. Since the seismic waves are significantly damped before they can spread laterally around the crust, magnetospheric wave emission occurs primarily near the initial epicenter of the quake. Our simulations suggest that non-axisymmetric quakes will launch a mixture of Alfv\'en and fast magnetosonic waves into the magnetosphere. The results will be important for interpreting magnetar bursts and understanding the possible trigger mechanisms of fast radio bursts. - oai:arXiv.org:2508.12567v2 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - replace + Fri, 23 Jan 2026 00:00:00 -0500 + cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yuanhong Qu, Ashley Bransgrove + H. B. C\^amara, A. Smetana, A. Tursunov - SISSI: Supernovae in a stratified, shearing interstellar medium. II. Star formation near the Sun is quenched by expansion of the Local Bubble - https://arxiv.org/abs/2509.04221 - arXiv:2509.04221v2 Announce Type: replace -Abstract: The age of the Local Bubble (LB) constrains the timescale on which the interstellar medium in the solar neighborhood evolves. Previous estimates placed the age of the LB at \sim 14 Myr, and attributed its expansion to \sim 15-20 supernovae (SNe), yet a companion paper suggests this age may be overestimated. We place new constraints on the age of the LB and re-evaluate the question whether its expansion triggered or suppressed local star formation. We reconstruct the LB's geometry and momentum using publicly available 3D dust maps and compare them to the high-quality sample of simulated supernova remnants in the SISSI project. Independent constraints on the star-formation history and supernova rate are obtained from a Gaia DR3-based census of nearby star clusters. We find that \sim 7-59 SNe over \sim 5.8 Myr to \sim 2.8 Myr, respectively, are required to explain both the LB's momentum and size and confirm that such a high supernova rate can be sustained by local star clusters. Our analysis yields a substantially smaller LB age than previous estimates, requiring a correspondingly larger number of SNe, driving its expansion. We show that this result is in tension with the conclusion that the LB is powered solely by SNe from the Scorpius-Centaurus OB association, which ceased star formation around the time the LB formed. If our estimates are correct, it follows that the majority of star formation in the solar neighborhood happened before the formation of the LB and was not triggered by its expansion. Instead, the SNe that powered the LB appear to overall have quenched the ongoing star formation process. This does not rule out that star formation in the clouds, located near its current edge, could have been affected by the LB expansion. - oai:arXiv.org:2509.04221v2 - astro-ph.GA - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Leonard E. C. Romano, Andreas Burkert + Natural Language-Driven Global Mapping of Martian Landforms + https://arxiv.org/abs/2601.15949 + arXiv:2601.15949v1 Announce Type: cross +Abstract: Planetary surfaces are typically analyzed using high-level semantic concepts in natural language, yet vast orbital image archives remain organized at the pixel level. This mismatch limits scalable, open-ended exploration of planetary surfaces. Here we present MarScope, a planetary-scale vision-language framework enabling natural language-driven, label-free mapping of Martian landforms. MarScope aligns planetary images and text in a shared semantic space, trained on over 200,000 curated image-text pairs. This framework transforms global geomorphic mapping on Mars by replacing pre-defined classifications with flexible semantic retrieval, enabling arbitrary user queries across the entire planet in 5 seconds with F1 scores up to 0.978. Applications further show that it extends beyond morphological classification to facilitate process-oriented analysis and similarity-based geomorphological mapping at a planetary scale. MarScope establishes a new paradigm where natural language serves as a direct interface for scientific discovery over massive geospatial datasets. + oai:arXiv.org:2601.15949v1 + cs.AI + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 + cross + http://creativecommons.org/publicdomain/zero/1.0/ + Yiran Wang, Shuoyuan Wang, Zhaoran Wei, Jiannan Zhao, Zhonghua Yao, Zejian Xie, Songxin Zhang, Jun Huang, Bingyi Jing, Hongxin Wei - A multiwavelength study of the new Galactic center black hole candidate MAXI J1744-294 - https://arxiv.org/abs/2509.14465 - arXiv:2509.14465v2 Announce Type: replace -Abstract: For the first time in nearly a decade, a bright new transient was detected in the central parsec (pc) of the Galaxy. MAXI J1744-294 was never observed in outburst prior to January 2025. We present the results of a broadband, multi-wavelength study of MAXI J1744-294, including data from the NuSTAR, Chandra, XMM-Newton, Swift, and NICER X-ray telescopes, as well as complementary radio and near-infrared observations. We analyze the changing X-ray emission as the outburst evolved from the high/soft to the low/hard state. Using relativistic reflection features in the data, we estimate a spin of $a>0.92$ and viewing inclination $\theta=28^{+3}_{-4}$ deg. Based on the spectral and temporal characteristics of the source, we identify MAXI J1744-294 as a candidate black hole (BH) low-mass X-ray binary (LMXB) -- the fourth candidate BH transient discovered within a (projected) distance of one pc from the Galactic supermassive black hole Sgr A*. This discovery provides further evidence for a cusp of BH-LMXBs in the central pc of our Galaxy, as argued for in previous observational studies and suggested by analytical and theoretical work. Our ongoing multi-wavelength study, involving a complementary range of observatories and spanning different outburst states, can serve as a model for future time domain astrophysics research. - oai:arXiv.org:2509.14465v2 + Photon-dark photon oscillation in M87 and Crab Nebula environments + https://arxiv.org/abs/2601.15985 + arXiv:2601.15985v1 Announce Type: cross +Abstract: Compact astrophysical systems such as neutron stars and black holes provide powerful laboratories for testing feebly coupled dark photons (DPs). We investigate light DPs kinetically mixed with the visible photon that need not be the dark matter, focusing on resonant photon-DP oscillations in magnetized, modeled plasma environments. We show that realistic non-monotonic plasma density profiles generically enhance resonant conversion relative to monotonic models, leading to substantially stronger constraints on the photon-DP kinetic mixing parameter ($\epsilon$). Using spectral data from the supermassive black hole (SMBH) M87*, extending to the LOFAR band, we derive a bound $\epsilon \simeq 7\times10^{-6}$ at the DP mass $m_{A'} \simeq 5\times10^{-7}\,\mathrm{eV}$ for oscillation distance $3r_{\rm ph}$, where $r_{\rm ph}$ denotes the photon sphere radius. From the Crab pulsar-wind Nebula, we obtain an even stronger constraint, $\epsilon \simeq 8\times10^{-7}$ at $m_{A'} \simeq 4\times10^{-9}\,\mathrm{eV}$ for oscillation baselines of order $10^{3}\,\mathrm{km}$, surpassing existing astrophysical limits in realistic plasma backgrounds. While laboratory and cosmological bounds remain slightly stronger at comparable masses, observation of compact objects with larger surface magnetic fields and measurements of photon spectra at lower frequencies would enhance the limits on the photon-DP coupling by orders of magnitude. + oai:arXiv.org:2601.15985v1 + hep-ph astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Shifra Mandel (Columbia Astrophysics Laboratory), Kaya Mori (Columbia Astrophysics Laboratory), Paul A. Draghis (MIT Kavli Institute for Astrophysics and Space Research), Mark Reynolds (Department of Astronomy, Ohio State University), Chichuan Jin (National Astronomical Observatories, Chinese Academy of Sciences), Maxime Parra (Department of Physics, Ehime University), Benjamin Levin (Columbia Astrophysics Laboratory), Eric Miao (Columbia Astrophysics Laboratory), Noa Grollimund (Universit\'e Paris Cit\'e, Universit\'e Paris-Saclay), Anna Ciurlo (UCLA Department of Physics and Astronomy), Sean A. Granados (UCLA Department of Physics and Astronomy), Gaurava K. Jaisawal (DTU Space, Technical University of Denmark), Lorenzo Marra (INAF Istituto di Astrofisica e Planetologia Spaziali), Matteo Bachetti (INAF-Osservatorio Astronomico di Cagliari), Fiamma Capitanio (INAF Istituto di Astrofisica e Planetologia Spaziali), Nathalie Degenaar (Anton Pannekoek Institute for Astronomy, University of Amsterdam), Charles J. Hailey (Columbia Astrophysics Laboratory), JaeSub Hong (Center for Astrophysics | Harvard \& Smithsonian), Sara Motta (INAF-Osservatorio Astronomico di Brera), Gabriele Ponti (INAF-Osservatorio Astronomico di Brera), Michael M. Shara (Department of Astrophysics, American Museum of Natural History), Megumi Shidatsu (Department of Physics, Ehime University), John A. Tomsick (Space Sciences Laboratory, University of California, Berkeley), Randall Campbell (W.M. Keck Observatory), St\'ephane Corbel (Universit\'e Paris Cit\'e, Universit\'e Paris-Saclay), Rob Fender (Astrophysics, Department of Physics, University of Oxford), Andrea Ghez (UCLA Department of Physics and Astronomy), Jonathan Grindlay (Center for Astrophysics | Harvard \& Smithsonian), Daryl Haggard (Department of Physics, McGill University), Matthew W. Hosek Jr. (UCLA Department of Physics and Astronomy), Ole K\"onig (Center for Astrophysics | Harvard \& Smithsonian), Kai Matsunaga (Department of Physics, Graduate School of Science, Kyoto University), Romana Miku\v{s}incov\'a (INAF Istituto di Astrofisica e Planetologia Spaziali), Melania Nynka (MIT Kavli Institute for Astrophysics and Space Research), Grace Sanger-Johnson (Department of Physics and Astronomy, Michigan State University), Giovanni Stel (INAF-Osservatorio Astronomico di Brera), Antonella Tarana (INAF Istituto di Astrofisica e Planetologia Spaziali), Rudy Wijnands (Anton Pannekoek Institute for Astronomy, University of Amsterdam), Shuo Zhang (Department of Physics and Astronomy, Michigan State University) + Fri, 23 Jan 2026 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Tanmay Kumar Poddar, Sourov Roy, Pratick Sarkar - A HyperFlash and \'ECLAT view of the local environment and energetics of the repeating FRB 20240619D - https://arxiv.org/abs/2509.16374 - arXiv:2509.16374v2 Announce Type: replace -Abstract: Time-variable propagation effects provide a window into the local plasma environments of repeating fast radio burst (FRB) sources. Here we report high-cadence observations of FRB 20240619D, as part of the HyperFlash and \'ECLAT programs. We observed for $500$h and detected $217$ bursts, including $10$ bursts with high fluence ($>25$ Jy ms) and implied energy. We track burst-to-burst variations in dispersion measure (DM) and rotation measure (RM), from which we constrain the parallel magnetic field strength in the source's local environment: $0.27\pm0.13$ mG. Apparent DM variations between sub-bursts in a single bright event are interpreted as coming from plasma lensing or variable emission height. We also identify two distinct scintillation screens along the line of sight, one associated with the Milky Way and the other likely located in the FRB's host galaxy or local environment. Together, these (time-variable) propagation effects reveal that FRB 20240619D is embedded in a dense, turbulent and highly magnetised plasma. The source's environment is more dynamic than that measured for many other (repeating) FRB sources, but less extreme compared to several repeaters that are associated with a compact, persistent radio source. FRB 20240619D's cumulative burst fluence distribution shows a power-law break, with a flat tail at high energies. Along with previous studies, this emphasises a common feature in the burst energy distribution of hyperactive repeaters. Using the break in the burst fluence distribution, we estimate a source redshift of $z=0.042$-$0.240$. We discuss FRB 20240619D's nature in the context of similar studies of other repeating FRBs. - oai:arXiv.org:2509.16374v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Different effects of the Lorentz and Gaussian bump functions on the formation of primordial black holes and secondary gravitational waves + https://arxiv.org/abs/2403.15979 + arXiv:2403.15979v3 Announce Type: replace +Abstract: Scalar perturbations in the inflation can be amplified when the base inflation potential $V_b(\phi)$ incorporates a local bump $f(\phi)$ such as $V(\phi)=V_b(\phi)(1+f(\phi))$. This modification will lead to a peak in the curvature power spectrum, increasing a significant abundance of primordial black holes (PBHs). However, since there is no underlying physical reason for the choice of $f(\phi)$, it is essential to investigate the effects of various bump functions on PBH generation. In this paper, we choose the well-known Starobinsky potential as the base inflation potential to compare the effects produced by different bumps, specifically focusing on the Lorentz and Gaussian bumps which are widely used. To clearly illustrate the differences between these two bumps, we keep parameters in bump functions the same. We find an interesting and novel result that the Lorentz cases manifest a stronger ability to enhance the power spectrum and produce more abundance of PBHs than Gaussian cases. Moreover, we also investigate the different effects of bump functions on the scalar-induced gravitational waves (SIGWs). The results indicate that the Lorentz bump generates SIGWs with a higher energy density, which can be potentially detected in the future. Our study gives valuable insights into the choice and constraints on the bump functions, and the different effects may distinguish the two bump cases for practical purposes in future experiments. + oai:arXiv.org:2403.15979v3 + astro-ph.CO + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1093/mnras/stag090 - O. S. Ould-Boukattine, A. J. Cooper, J. W. T. Hessels, D. M. Hewitt, S. K. Ocker, A. Moroianu, K. Nimmo, M. P. Snelders, I. Cognard, T. J. Dijkema, M. Fine, M. P. Gawro\'nski, W. Herrmann, J. Huang, F. Kirsten, Z. Pleunis, W. Puchalska, S. Ranguin, T. Telkamp + 10.1016/j.dark.2026.102224 + Physics of the Dark Universe 51 (2026) 102224 + Wei Yang, Yu-Xuan Kang, Arshad Ali, Tao-Tao Sui, Chen-Hao Wu, Ya-Peng Hu - Light curves of time-dependent accretion disk in tidal disruption events - https://arxiv.org/abs/2509.16544 - arXiv:2509.16544v3 Announce Type: replace -Abstract: Tidal disruption events (TDEs) are believed to be an ideal laboratory for studying the evolution of accretion flow around a supermassive black hole (BH). In general, the mass feeding rate to the BH is suggested to be super-Eddington initially, and evolves to be sub-Eddington on timescales of years. In this paper, we carry out calculations of the time-dependent evolution of accretion disk in the standard environment of TDE, i.e., injecting matter at the circularization radius of the stellar debris in the form of $\dot M_{\rm inject} \propto t^{-5/3}$. One of the main findings is that when $\dot M_{\rm inject}$ evolves to a value around the Eddington accretion rate, the radiation pressure instability occurs. We test the influence of the model parameters on the light curves, such as the BH mass $M_{\rm BH}$, viscosity parameter $\alpha$, and mass-injecting radius $R_{\rm{out}}$, all of which are found to affect the light curves to some extent. In most cases, we find that the light curves oscillate significantly due to the radiation pressure instability. As an exception, when $\alpha$ is small or $R_{\rm{out}}$ is large, we find that the oscillations are completely suppressed. In this case, the light curve drops steeply and then becomes flat in the late-time evolution, which we apply to explain the observed ultraviolet (UV) light curves of ASASSN-15oi and ASASSN-14ae together with the assumption of a photosphere. Finally, we discuss the potential applications of our time-dependent accretion disk model to explaining multi-band light curves of TDEs in the future. - oai:arXiv.org:2509.16544v3 + Evidence for GeV emission of the superluminous supernova SN 2017egm + https://arxiv.org/abs/2407.05968 + arXiv:2407.05968v2 Announce Type: replace +Abstract: Superluminous supernovae (SLSNe) are a new class of transients with luminosities $\sim10 -100$ times larger than the usual core-collapse supernovae (SNe). Their origin is still unclear and one widely discussed scenario involves a millisecond magnetar central engine. The GeV-TeV emission of SLSNe has been predicted in the literature but has not been convincingly detected yet. Here we report the results of the search for $\gamma$-ray emission in the direction of SN 2017egm, one of the closest SLSNe detected so far, using 15 years of {\it Fermi}-LAT Pass 8 data. There is a transient $\gamma$-ray source appearing about 2 months after this event and lasting a few months. Monte Carlo simulations show that the $\gamma$-ray signal has a global significance of {\it at least} 4$\sigma$. Both the peak time and the luminosity of the GeV emission are consistent with the magnetar model prediction, suggesting that such a GeV transient is the high-energy counterpart of SN 2017egm and the central engine of this SLSNe is a young magnetar. + oai:arXiv.org:2407.05968v2 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Chenlei Guo, Erlin Qiao + Shang Li, Yun-Feng Liang, Neng-Hui Liao, Lei Lei, Yi-Zhong Fan - The impact of cosmic filaments on the abundance of satellite galaxies - https://arxiv.org/abs/2509.22179 - arXiv:2509.22179v2 Announce Type: replace -Abstract: The impact of cosmic web environments on galaxy properties plays a critical role in understanding galaxy formation. Using the state-of-the-art cosmological simulation IllustrisTNG, we investigate how satellite galaxy abundance differs between filaments and the field, with filaments identified using the DisPerSE algorithm. When filaments are identified using galaxies as tracers, we find that, across all magnitude bins, central galaxies in filaments tend to host more satellite galaxies than their counterparts in the field, in qualitative agreement with observational results from the Sloan Digital Sky Survey. The average ratios between satellite luminosity functions in filaments and the field are $3.49$, $2.61$, and $1.90$ in the central galaxy $r$-band magnitude bins of $M_{r, {\rm cen}} \sim -22$, $-21$, and $-20$, respectively. We show that much of this excess can be attributed to the higher host halo masses of galaxies in filaments. After resampling central galaxies in both environments to match the halo mass distributions within each magnitude bin, the satellite abundance enhancement in filaments is reduced by up to $79 \%$. Additionally, the choice of tracers used to identify filaments introduces a significant bias: when filaments are identified using the dark matter density field, the environmental difference in satellite abundance is reduced by more than $70 \%$; after further resampling in both magnitude and halo mass, the difference is further suppressed by another $\sim 60$--$95 \%$. Our results highlight the importance of halo mass differences and tracer choice biases when interpreting and understanding the impact of environment on satellite galaxy properties. - oai:arXiv.org:2509.22179v2 - astro-ph.GA + Running the small-correlated-against-large estimator at scale: Applications of small-scale CMB lensing estimators on realistic simulations + https://arxiv.org/abs/2409.05326 + arXiv:2409.05326v2 Announce Type: replace +Abstract: The Small-Correlated-Against-Large Estimator (SCALE) for small-scale lensing of the cosmic microwave background (CMB) provides a novel method for measuring the amplitude of CMB lensing power without the need for reconstruction of the lensing field. In our previous study, we showed that the SCALE method can outperform existing reconstruction methods to detect the presence of lensing at small scales ($\ell \gg 3000$). Here we develop a procedure to include information from SCALE in cosmological parameter inference. We construct a precise neural network emulator to quickly map cosmological parameters to desired CMB observables such as temperature and lensing power spectra and SCALE cross spectra. We also outline a method to apply SCALE to full-sky maps of the CMB temperature field, and construct a likelihood for the application of SCALE in parameter estimation. SCALE supplements conventional observables such as the CMB power spectra and baryon acoustic oscillations in constraining parameters that are sensitive to the small-scale lensing amplitude such as the neutrino mass $m_\nu$. We show that including estimates of the small-scale lensing amplitude from SCALE in such an analysis provides enough constraining information to measure the minimum neutrino mass at $4\sigma$ significance in the scenario of minimal mass, and higher significance for higher mass. Finally, we show that SCALE will play a powerful role in constraining models of clustering that generate scale-dependent modulation to the distribution of matter and the lensing power spectrum, as predicted by models of warm or fuzzy dark matter. + oai:arXiv.org:2409.05326v2 astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Yuxi Meng, Haonan Zheng, Shihong Liao, Lizhi Xie, Lan Wang, Hongxiang Chen, Liang Gao, Quan Guo, Yingjie Jing, Jie Wang, Hang Yang, Guangquan Zeng + http://creativecommons.org/licenses/by-nc-sa/4.0/ + 10.1103/zt71-zrmd + Phys. Rev. D 113, 023535, Published 21 January, 2026 + Victor C. Chan, Ren\'ee Hlo\v{z}ek, Joel Meyers, Alexander van Engelen - BAO miscalibration cannot rescue late-time solutions to the Hubble tension - https://arxiv.org/abs/2510.01974 - arXiv:2510.01974v2 Announce Type: replace -Abstract: Baryon Acoustic Oscillation (BAO) measurements play a key role in ruling out post-recombination solutions to the Hubble tension. However, because the data compression leading to these measurements assumes a fiducial $\Lambda$CDM cosmology, their reliability in testing late-time modifications to $\Lambda$CDM has at times been called into question. We play devil's advocate and posit that fiducial cosmology assumptions do indeed affect BAO measurements in such a way that low-redshift acoustic angular scales (proportional to the Hubble constant $H_0$) are biased low, and test whether such a rescaling can rescue post-recombination solutions. The answer is no. Firstly, strong constraints on the shape of the $z \lesssim 2$ expansion history from unanchored Type Ia Supernovae (SNeIa) prevent large deviations from $\Lambda$CDM. In addition, unless $\Omega_m$ is significantly lower than $0.3$, the rescaled BAO measurements would be in strong tension with geometrical information from the Cosmic Microwave Background. We demonstrate this explicitly on several dark energy (DE) models ($w$CDM, CPL DE, phenomenologically emergent DE, holographic DE, $\Lambda_s$CDM, and the negative cosmological constant model), finding that none can address the Hubble tension once unanchored SNeIa are included. We argue that the $\Lambda_s$CDM sign-switching cosmological constant model possesses interesting features which make it the least unpromising one among those tested. Our results demonstrate that possible fiducial cosmology-induced BAO biases cannot be invoked as loopholes to the Hubble tension "no-go theorem", and highlight the extremely important but so far underappreciated role of unanchored SNeIa in ruling out post-recombination solutions. - oai:arXiv.org:2510.01974v2 + Cosmic acceleration and the Hubble tension from baryon acoustic oscillation data + https://arxiv.org/abs/2409.13399 + arXiv:2409.13399v3 Announce Type: replace +Abstract: We investigate the null tests of cosmic accelerated expansion by using the Baryon Acoustic Oscillation (BAO) data measured by the Dark Energy Spectroscopic Instrument (DESI) and reconstruct the dimensionless Hubble parameter $E(z)$ from the DESI BAO Alcock-Paczynski (AP) data using Gaussian process to perform the null test. We find strong evidence of accelerated expansion from the DESI BAO AP data. By reconstructing the deceleration parameter $q(z)$ from the DESI BAO AP data, we find that accelerated expansion persisted until $z \lesssim 0.7$ with a 99.7\% confidence level. Additionally, to provide insights into the Hubble tension problem, we propose combining the reconstructed $E(z)$ with $D_H/r_d$ data to derive the model-independent result $r_d h=99.8\pm 3.1$ Mpc. This result is consistent with measurements from cosmic microwave background (CMB) anisotropies using the $\Lambda$CDM model. We also propose a model-independent method for reconstructing the comoving angular diameter distance $D_M(z)$ from the distance modulus $\mu$ using SNe Ia data and combining this result with DESI BAO data of $D_M/r_d$ to constrain the value of $r_d$. We find that the value of $r_d$ derived from this model-independent method is smaller than that obtained from CMB measurements, with a significant discrepancy of at least 4.17$\sigma$. All the conclusions drawn in this paper are independent of cosmological models and gravitational theories. + oai:arXiv.org:2409.13399v3 astro-ph.CO gr-qc - hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/pn9j-8whx - Davide Pedrotti, Luis A. Escamilla, Valerio Marra, Leandros Perivolaropoulos, Sunny Vagnozzi + 10.1088/0256-307X/43/1/011101 + Chinese Phys. Lett. 43 (2026) 011101 + Xuchen Lu, Shengqing Gao, Yungui Gong - Improved Radiative Transfer Corrections in Helium Emission Lines - https://arxiv.org/abs/2510.02045 - arXiv:2510.02045v2 Announce Type: replace -Abstract: We present a new detailed model of the He I collisional-recombination spectrum based on the most up-to-date atomic data. The model accounts for radiative transfer effects and the influence of a non-zero optical depth in He I lines arising from transitions to the metastable 2^3S state. The model reveals substantial deviations in the emissivities of the lambda3889 and lambda7065 lines in the case of a non-zero optical depth, with previous models systematically underestimating and overestimating them by 5 to 20 percent, respectively. In the optically thin case, however, our results show good agreement with previous studies. Using the new model, we compute optically thin emissivities for a wide set of UV, optical, and IR He I recombination lines over a fine grid of electron densities and temperatures typical for H II regions and planetary nebulae (1 <= ne <= 10^4 cm^-3, 8000 <= Te <= 22000 K). In addition, we present new fitting formulae for radiative transfer corrections for several He I lines relevant to optical and near-infrared observations, covering 0 <= tau_3889 <= 10 within the same density and temperature ranges. The accuracy of the obtained approximations is <= 0.1 percent within the specified parameter range. These results can be readily implemented in modern codes for determining the primordial 4He abundance and are also applicable to a broader range of spectroscopic analyses of He I emission lines. - oai:arXiv.org:2510.02045v2 + Turbulent dynamos in a collapsing cloud + https://arxiv.org/abs/2503.19131 + arXiv:2503.19131v2 Announce Type: replace +Abstract: The amplification of magnetic fields is crucial for understanding the observed magnetization of stars and galaxies. Turbulent dynamo is the primary mechanism responsible for that but the understanding of its action in a collapsing environment is still rudimentary and relies on limited numerical experiments. We develop an analytical framework and perform numerical simulations to investigate the behavior of small-scale and large-scale dynamos in a collapsing turbulent cloud. This approach is also applicable to expanding environments and facilitates the application of standard dynamo theory to evolving systems. Using a supercomoving formulation of the magnetohydrodynamic (MHD) equations, we demonstrate that dynamo action in a collapsing background leads to a super-exponential growth of magnetic fields in time, significantly faster than the exponential growth seen in stationary turbulence. The enhancement is mainly due to the increasing eddy turnover rate during the collapse, which boosts the instantaneous growth rate of the dynamo. We also show that the scaling of final saturated magnetic field strength with density robustly exceeds the expectation from considerations of pure flux-freezing. Apart from establishing a formal framework for studying magnetic field evolution in collapsing (or expanding) turbulent plasmas, these findings suggest that during star and galaxy formation magnetic fields can become dynamically relevant much earlier than previously thought. + oai:arXiv.org:2503.19131v2 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.CO + astro-ph.SR + physics.plasm-ph + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-sa/4.0/ - 10.1103/rf57-k9yj - Oleg Kurichin, Alexandre Ivanchik + http://creativecommons.org/licenses/by/4.0/ + 10.1103/fp1v-xrr5 + Muhammed Irshad P, Pallavi Bhat, Kandaswamy Subramanian, Anvar Shukurov - Vision-Based CNN Prediction of Sunspot Numbers from SDO/HMI Images - https://arxiv.org/abs/2510.03473 - arXiv:2510.03473v2 Announce Type: replace -Abstract: Sunspot numbers provide the longest continuous record of solar activity and remain a key index for heliophysical research and space-weather applications. Standard sunspot determination relies on visual inspection and algorithmic feature-detection pipelines, both of which involve methodological choices and can be sensitive to image quality and implementation details. Convolutional neural networks (CNNs) offer an alternative by learning an end-to-end mapping from solar images to a scalar index, reducing reliance on explicit, handcrafted feature design. Here we present a supervised vision-based regression framework to estimate the daily sunspot number from full-disk continuum images acquired by the Helioseismic and Magnetic Imager (HMI) onboard NASA Solar Dynamics Observatory (SDO). We pair daily images from 2011-2024 with the SILSO Version 2.0 daily sunspot number and train a CNN to infer the scalar value at the observation time of each image. On an independent test split, the model achieves R2=0.964, RMSE=9.75, and MAE=6.74, indicating close agreement with SILSO across a wide activity range. Interpretability analyses using Grad-CAM and Integrated Gradients show that the network attributions concentrate on sunspot-bearing regions, supporting the physical plausibility of the learned representations. These results demonstrate the feasibility of direct image-to-index estimation for scalable solar monitoring. Future work will explore multimodal fusion with complementary observables (e.g., magnetograms) and standardized cross-cycle benchmarks to assess robustness under changing solar conditions. - oai:arXiv.org:2510.03473v2 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + WINTER on S250206dm: A near-infrared search for an electromagnetic counterpart to a gravitational-wave event + https://arxiv.org/abs/2504.12384 + arXiv:2504.12384v2 Announce Type: replace +Abstract: We present near-infrared follow-up observations of the International Gravitational Wave Network (IGWN) event S250206dm with the Wide-Field Infrared Transient Explorer (WINTER). WINTER is a near-infrared time-domain survey designed for electromagnetic follow-up of gravitational-wave sources localized to $\leq$300 deg$^{2}$. The instrument's wide field of view (1.2 deg$^2$), dedicated 1-m robotic telescope, and near-infrared coverage (0.9-1.7 microns) are optimized for searching for kilonovae, which are expected to exhibit a relatively long-lived near-infrared component. S250206dm is the only neutron star merger in the fourth observing run (to date) localized to $\leq$300 deg$^{2}$ with a False Alarm Rate below one per year. It has a $55\%$ probability of being a neutron star-black hole (NSBH) merger and a $37\%$ probability of being a binary neutron star (BNS) merger, with a $50\%$ credible region spanning 38 deg$^2$, an estimated distance of 373 Mpc, and an overall false alarm rate of approximately one in 25 years. WINTER covered $43\%$ of the probability area at least once and $35\%$ at least three times. Through automated and human candidate vetting, all transient candidates found in WINTER coverage were rejected as kilonova candidates. Unsurprisingly, given the large estimated distance of 373 Mpc, the WINTER upper limits do not constrain kilonova models. This study highlights the promise of systematic infrared searches and the need for future wider and deeper infrared surveys. + oai:arXiv.org:2504.12384v2 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Fabian C. Quintero-Pareja, Diederik A. Montano-Burbano, Santiago Quintero-Pareja, D. Sierra-Porta + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1088/1538-3873/ade478 + PASP Volume 137, Issue 7, 2025 + Danielle Frostig, Viraj R. Karambelkar, Robert D. Stein, Nathan P. Lourie, Mansi M. Kasliwal, Robert A. Simcoe, Mattia Bulla, Tomas Ahumada, Geoffrey Mo, Josiah Purdum, Jill Juneau, Andrew Malonis, Gabor Furesz - Is the high-energy environment of K2-18b special? - https://arxiv.org/abs/2510.06939 - arXiv:2510.06939v2 Announce Type: replace -Abstract: K2-18b lies near the radius valley that separates super-Earths and sub-Neptunes, marking a key transitional regime in planetary and atmospheric composition. The system offers a valuable opportunity to study how M-dwarf high-energy stellar radiation influences atmospheric stability and the potential for sustaining volatile species, especially important in the context of the upcoming ELT and its ANDES spectrograph. This study characterizes the high-energy environment of K2-18 with X-ray observations from eROSITA, the soft X-ray instrument on the Spectrum-Roentgen-Gamma (SRG) mission, Chandra, and XMM-Newton. We derive a representative 0.2-2 keV X-ray flux with an APEC thermal plasma model fitted with the Bayesian X-ray Analysis (BXA). With the observed X-ray flux from the exoplanet host star, we estimate the photoevaporative mass loss of exoplanet K2-18b using the energy-limited model. In addition, we examine the thermal structure of the system based on a hydrodynamic model. In 100 ks XMM-Newton observation we identified K2-18 as a very faint X-ray source with $\mathrm{F_X = 10^{-15}\ erg\,s^{-1}\,cm^{-2}}$, with an activity level of (Lx/Lbol) $\sim 10^{-5}$. A small flare has been detected during the observation. The planet is irradiated by an X-ray flux of $\mathrm{F_{pl,X} = 12\pm3\ erg\,s^{-1}\,cm^{-2}}$. The X-ray flux measurement of K2-18 gives important limitations for atmospheric escape and photochemical modeling of its exoplanets. Despite its near orbit around an M-dwarf star, K2-18b's low activity level environment suggests that it can retain an atmosphere, supporting recent tentative detections of atmospheres. - oai:arXiv.org:2510.06939v2 - astro-ph.EP + Distinguishing the Origin of Eccentric Black Hole Mergers with Gravitational-wave Spin Measurements + https://arxiv.org/abs/2505.13589 + arXiv:2505.13589v2 Announce Type: replace +Abstract: It remains an open question whether the binary black hole mergers observed with gravitational-wave detectors originate from the evolution of isolated massive binary stars or were dynamically driven by perturbations from the environment. Recent evidence for non-zero orbital eccentricity in a handful of events is seen as support for a non-negligible fraction of the population experiencing external driving of the merger. However, it is unclear from which formation channel eccentric binary black-hole mergers would originate: dense star clusters, hierarchical field triples, active galactic nuclei, or wide binaries in the Galaxy could all be culprits. Here, we investigate whether the spin properties of eccentric mergers could be used to break this degeneracy. Using the fact that different formation channels are predicted to either produce eccentric mergers with mutually aligned or randomly oriented black-hole spins, we investigate how many confident detections would be needed in order for the two models to be statistically distinguishable. If a few percent of binary black hole mergers retain measurable eccentricity in the bandwidth of ground-based detectors, we report a $\sim9\,\%$ chance that we could confidently distinguish both models (Bayes factor $\ln\mathcal{B}>3$) after the fifth observing run of the LIGO-Virgo-KAGRA detector network, $\sim63\,\%$ for LIGO A#, and $\sim98\,\%$ for the Einstein Telescope and Cosmic Explorer. + oai:arXiv.org:2505.13589v2 astro-ph.HE astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - S. Rukdee, M. G\"udel, I. Vilovi\'c, K. Poppenh\"ager, S. Boro Saikia, J. Buchner, B. Stelzer, G. Roccetti, J. V. Seidel, V. Burwitz + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.3847/2041-8213/ae1d66 + Jakob Stegmann et al 2025 ApJL 994 L47 + Jakob Stegmann, Davide Gerosa, Isobel Romero-Shaw, Giulia Fumagalli, Hiromichi Tagawa, Lorenz Zwick - Cavendish experiment with fast radio bursts on cosmological scales - https://arxiv.org/abs/2510.11022 - arXiv:2510.11022v2 Announce Type: replace -Abstract: A key measure of gravity is the relation between the Weyl potential $\Psi+\Phi$ and the matter overdensity $\delta_m$, encapsulated as an effective gravitational constant $G_{\rm light}$ for light motion. Its value, along with possible spatial and temporal variations, is essential for probing physics beyond Einstein gravity. However, the absence of an unbiased proxy for $\delta_m$ prevents the direct measurement of $G_{\rm light}$. In this letter, we point out that the equivalence principle guarantees the dispersion measure (DM) of localized fast radio bursts (FRBs) as a good proxy for $\delta_m$. We further propose an FRB-based estimator $F_G$ to directly measure $G_{\rm light}$, combining galaxy-DM of localized FRBs and galaxy-weak lensing cross-correlations. With a conservative cut $k\leq 0.1h$/Mpc, the measurement can achieve a precision of $\lesssim 10\% \sqrt{10^5/N_{\rm FRB}}$ over 10 equal-width redshift bins at $z\lesssim 1$. The major systematic error, arising from the clustering bias of electrons traced by the FRB DM, remains subdominant at the $5\%$ level. It can be further mitigated to the $\lesssim 1\%$ level, based on the gastrophysics-agnostic behavior that the clustering bias of total baryons (ionized diffuse gas, stars, neutral hydrogen, etc) approaches unity at sufficiently large scales. Therefore, FRBs shed light on gravitational physics across spatial and temporal scales spanning 20 orders of magnitude. - oai:arXiv.org:2510.11022v2 - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + The AURORA Survey: Tracing Galactic Outflows at $z\gtrsim2.5$ with JWST/NIRSpec NUV Absorption Lines + https://arxiv.org/abs/2506.17381 + arXiv:2506.17381v2 Announce Type: replace +Abstract: We probe galactic-scale outflows in star-forming galaxies at $z\gtrsim2.5$ drawn from the \textit{JWST}/NIRSpec AURORA program. For the first time, we directly compare outflow properties from the early universe to the present day using near-UV absorption lines. We measure ISM kinematics from Fe\,{\sc ii} and Mg\,{\sc ii} absorption features in 41 and 43 galaxies, respectively, and examine how these kinematics correlate with galaxy properties. We find that galaxies with outflows tend to have higher stellar masses, and that maximum outflow velocities increase with stellar mass, SFR, UV slope $\beta$, $E(B-V)$, and $A_V$. We also find that Mg\,{\sc ii} emission is more common in galaxies with lower masses, higher sSFRs, and less dust. These trends are consistent with those in star-forming galaxies at $z<2$ when using the same outflow tracers, suggesting that the feedback from star formation has played a persistent role in shaping galaxy evolution over cosmic time. We also directly compare near-UV and far-UV features in the same NIRSpec spectrum for a $z=5.19$ galaxy, finding consistent ISM kinematics and demonstrating that different tracers yield comparable measurements. We also detect Na\,D absorption in 10 galaxies, which have higher stellar mass, SFR, and dust attenuation compared to galaxies without Na\,D absorption, which is consistent with $z\sim0$ studies. The broad continuum coverage and sensitivity of NIRSpec will enable future studies with larger samples, allowing for robust tests of these trends across a wider dynamic range of galaxy properties. + oai:arXiv.org:2506.17381v2 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Shuren Zhou, Pengjie Zhang + 10.3847/1538-4357/ae10b3 + Emily Kehoe, Alice E. Shapley, Ryan L. Sanders, Naveen A. Reddy, Natalie Lam, Leonardo Clarke, Fergus Cullen, Richard S. Ellis, N. M. Forster Schreiber, Tucker Jones, Ali Ahmad Khostovan, Derek J. McLeod, Ross J. McLure, Desika Narayanan, Pascal Oesch, Anthony J. Pahl - Strong Evidence for Cosmic Ray-Supported $\sim$L$^{\ast}$ Galaxy Halos via X-ray \& tSZ Constraints - https://arxiv.org/abs/2510.13959 - arXiv:2510.13959v2 Announce Type: replace -Abstract: Many state-of-the-art galaxy simulations featuring traditional feedback modes have significant challenges producing enough extended soft X-ray ($\sim 0.5-2$ keV) emission at R $\sim 0.5-1$ R$_{\rm vir}$ observed around galaxies with stellar masses M$_{\rm \ast} \lesssim 10^{11} \rm M_\odot$, without violating galaxy mass function constraints. Moreover, thermal Sunyaev-Zel'dovich (tSZ) measurements probing the thermal pressure of similar galaxies indicate it is orders-of-magnitude lower than predictions from simple halo hydrodynamics and many hydrodynamical simulations. We demonstrate that these constraints can be met congruously with a large non-thermal pressure contribution in the form of cosmic rays (CRs) from SNe and/or AGN, which lowers the tSZ signal while CR leptons produce plentiful soft X-rays via inverse Compton scattering of the CMB. The combination of these two observations is far more constraining on the pressure budget of galactic halos than either alone -- if these novel tSZ and X-ray observations are borne out by future studies, then taken together they reveal \textit{the strongest evidence for CR support in halos to date}. Conversely, it is very difficult to produce the extended X-rays via traditional thermal emission without increasing the overall thermal pressure and thus tSZ signal in tandem, making these tensions even worse. Finally, tSZ \& X-rays together unlock a novel observational method to constrain halo CR pressure relative to thermal pressure, with implications for CR transport parameters and AGN feedback energetics across various galaxy mass scales. Taking the currently observed constraints at M$_{\rm halo} \sim 10^{\rm 12} \rm M_\odot$ imply the halo CR pressure must at least be equal to the gas thermal pressure. - oai:arXiv.org:2510.13959v2 - astro-ph.GA + Self-bound hybrid stars with strong phase transitions can relieve major compact star observation tensions + https://arxiv.org/abs/2507.01371 + arXiv:2507.01371v2 Announce Type: replace +Abstract: Some recent pulsar observations cannot naturally fit into the conventional picture of neutron stars: the compact objects associated with HESS J1731-347 and XTE J1814-338 have too small radii in the low-mass regime, while the secondary component of GW190814 is too massive for neutron stars to be compatible with constraints from the GW170817 event. In this study, we demonstrate that all these anomalous observations and tensions, together with other conventional ones such as recent NICER observations of PSR J0740+6620, J0030+0451, and PSR J0437-4715, can be naturally explained simultaneously by a new general type of self-bound hybrid stars with large density discontinuities, and thus are radially stable in either the slow or rapid phase transition context. As a proof of concept, we use hybrid quark stars, inverted hybrid stars, and hybrid strangeon stars as benchmark examples to explicitly demonstrate the advantage and feasibility of self-bound hybrid stars with strong phase transitions in relieving all tensions related to compact stars' masses, radii, and tidal deformabilities. + oai:arXiv.org:2507.01371v2 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + gr-qc + hep-ph + nucl-th + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.3847/2041-8213/ae2fd9 - ApJL 997 L13 (2026) - Sam B. Ponnada, Philip F. Hopkins, Yue Samuel Lu, Emily M. Silich, Iryna S. Butsky, Dusan Keres + Chen Zhang, Juan M. Z. Pretel, Renxin Xu - The selection function of the Gaia DR3 open cluster census - https://arxiv.org/abs/2510.18343 - arXiv:2510.18343v2 Announce Type: replace -Abstract: Open clusters are among the most useful and widespread tracers of Galactic structure. The completeness of the Galactic open cluster census, however, remains poorly understood. For the first time ever, we establish the selection function of an entire open cluster census, publishing our results as an open-source Python package for use by the community. Our work is valid for the Hunt & Reffert catalogue of clusters in Gaia DR3. We developed and open-sourced our cluster simulator from our first work. Then, we performed 80,590 injection and retrievals of simulated open clusters to test the Hunt & Reffert catalogue's sensitivity. We fit a logistic model of cluster detectability that depends only on a cluster's number of stars, median parallax error, Gaia data density, and a user-specified significance threshold. We find that our simple model accurately predicts cluster detectability, with a 94.53\% accuracy on our training data that is comparable to a machine-learning based model with orders of magnitude more parameters. Our model itself offers numerous insights on why certain clusters are detected. We briefly use our model to show that cluster detectability depends on non-intuitive parameters, such as a cluster's proper motion, and we show that even a modest 25 km/s boost to a cluster's orbital speed can result in an almost 3$\times$ higher detection probability, depending on its position. In addition, we publish our raw cluster injection and retrievals and cluster memberships, which could be used for a number of other science cases -- such as estimating cluster membership incompleteness. Using our results, selection effect-corrected studies are now possible with the open cluster census. Our work will enable a number of brand new types of study, such as detailed comparisons between the Milky Way's cluster census and recent extragalactic cluster samples. - oai:arXiv.org:2510.18343v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Machine-learning correction for the calorimeter saturation of cosmic-ray ions with the Dark Matter Particle Explorer: towards the PeV scale + https://arxiv.org/abs/2507.06626 + arXiv:2507.06626v2 Announce Type: replace +Abstract: The Dark MAtter Particle Explorer (DAMPE) instrument is a space-borne cosmic-ray detector, capable of measuring ion fluxes up to $\sim$500 TeV/n. This energy scale is made accessible through its calorimeter, which is the deepest currently operating in orbit. Saturation of the calorimeter readout channels starts occurring above $\sim$100 TeV of incident energy, and can significantly affect the primary energy reconstruction. Different techniques -- analytical and machine-learning based -- were developed to tackle this issue, focusing on the recovery of single-bar deposits, up to several hundreds of TeV. In this work, a new machine-learning technique is presented, which benefits from a unique model to correct the total deposited energy in DAMPE calorimeter. The described method is able to generalise its corrections for different ions and extend the maximum detectable incident energy to the PeV scale. This work is a continuation of the results presented in [1]. + oai:arXiv.org:2507.06626v2 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Emily L. Hunt, Tristan Cantat-Gaudin, Friedrich Anders, Sagar Malhotra, Lorenzo Spina, Alfred Castro-Ginard, Lorenzo Cavallo + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.1016/j.nima.2026.171306 + Andrea Serpolla, Andrii Tykhonov, Paul Coppin, Manbing Li, Andrii Kotenko, Enzo Putti-Garcia, Hugo Valentin Boutin, Mikhail Stolpovskiy, Jennifer Maria Frieden, Chiara Perrina, Xin Wu - Binding energy of compact stars and their non-radial oscillations - https://arxiv.org/abs/2510.18706 - arXiv:2510.18706v2 Announce Type: replace -Abstract: In the past years, a significant effort has been made with the scope of determining correlations, involving compact star properties, that are independent of the nuclear equation of state. Such universal relations are of utmost importance as they allow for the imposition of constraints on stellar properties without directly measuring them and they may also serve as a probe of General Relativity. In the present study, we investigated the possible existence of a universal relation between the binding energy of compact stars and the frequency of their non-radial oscillations. The main motivation was related to the fact that both of the aforementioned quantities might be measured in the occurrence of a supernova explosion. Interestingly, we found that there is a empirical relation between the oscillation frequency and the binding energy for both $f$ and $p_1$ modes, assuming hadronic stellar matter. The inclusion of hybrid equations of state, incorporating sharp phase transitions, was shown to result into deviations from the aforementioned quasi-universal relation. - oai:arXiv.org:2510.18706v2 + AT2019cmw: A highly luminous, cooling featureless TDE candidate from the disruption of a high mass star in an early-type galaxy + https://arxiv.org/abs/2507.07380 + arXiv:2507.07380v2 Announce Type: replace +Abstract: We present optical/UV photometric and spectroscopic observations, as well as X-ray and radio follow-up, of the extraordinary event AT2019cmw. With a peak bolometric luminosity of ~$\mathrm{10^{45.6}\,erg\,s^{-1}}$, it is one of the most luminous thermal transients ever discovered. Extensive spectroscopic follow-up post-peak showed only a featureless continuum throughout its evolution. This, combined with its nuclear location, blue colour at peak and lack of prior evidence of an AGN in its host lead us to interpret this event as a `featureless' tidal disruption event (TDE). It displays photometric evolution atypical of most TDEs, cooling from ~30 kK to ~10 kK in the first ~300 days post-peak, with potential implications for future photometric selection of candidate TDEs. No X-ray or radio emission is detected, placing constraints on the presence of on-axis jetted emission or a visible inner-accretion disk. Modelling the optical light curve with existing theoretical prescriptions, we find that AT2019cmw may be the result of the disruption of a star in the tens of solar masses by a supermassive black hole (SMBH). Combined with a lack of detectable star formation in its host galaxy, it could imply the existence of a localised region of star formation around the SMBH. This could provide a new window to probe nuclear star formation and the shape of the initial mass function (IMF) in close proximity to SMBHs out to relatively high redshifts. + oai:arXiv.org:2507.07380v2 astro-ph.HE - gr-qc - nucl-th - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - P. Laskos-Patkos, S. Papadopoulos, Ch. C. Moustakidis + 10.1093/mnras/stag130 + Jacob L. Wise, Daniel A. Perley, Nikhil Sarin, Tatsuya Matsumoto, K-Ryan Hinds, Yuhan Yao, Jesper Sollerman, Steve Schulze, Aleksandra Bochenek, Michael W. Coughlin, Kishalay De, Richard Dekany, Sara Frederick, Christoffer Fremling, Suvi Gezari, Matthew J. Graham, Anna Y. Q. Ho, Shrinivas Kulkarni, Russ R. Laher, Conor Omand, Natalya Johnson, Yashvi Sharma, Kirsty Taggart, Charlotte Ward, Avery Wold, Lin Yan - Galactic bars and active galactic nucleus fuelling in the second half of cosmic history - https://arxiv.org/abs/2510.23522 - arXiv:2510.23522v2 Announce Type: replace -Abstract: We investigate the role of galactic bars in fuelling and triggering Active Galactic Nucleus (AGN) in disc galaxies up to $z\sim 0.8$. We utilise a Deep Learning model, fine-tuned on Galaxy Zoo volunteer classifications, to identify (strongly and weakly) barred and unbarred disc galaxies in Hyper Suprime-Cam Subaru Strategic Program $i$-band images. We select AGN using three independent diagnostics: mid-infrared colours, X-ray detections, and spectral energy distribution (SED) fitting. The SED analysis, performed using CIGALE, quantifies the relative AGN contribution to the total galaxy luminosity ($f_{\rm AGN}$) and the AGN luminosity ($L_{\rm disc}$). We assess the impact of bars by comparing AGN incidence and properties in barred galaxies against carefully constructed redshift-, stellar mass-, and colour-matched unbarred control samples. Our binary AGN classification experiment demonstrates that barred disc galaxies host a higher fraction of AGN compared to their unbarred counterparts, though the significance depends on the AGN selection method, with a more modest excess for SED AGN, and control sample size. This suggests a contributing role for bars in the global AGN budget. The contribution of bars to AGN fuelling appears confined to systems where the AGN has a lower relative contribution to the host galaxy's emission ($f_{\rm AGN} < 0.75$). Crucially, we find a significant dearth of barred disc galaxies hosting AGN with $f_{\rm AGN} > 0.75$, independent of bar strength. Consistent with this, the fraction of barred galaxies among AGN hosts decreases with increasing $L_{\rm disc}$. Combined with previous results, we suggest that bars may contribute to fuelling the population of low-to-moderate luminosity AGN, but major mergers are the principal mechanism for triggering the most powerful and dominant accretion events. - oai:arXiv.org:2510.23522v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + The role of magnetic fields in shaping $\gamma$-ray emission from the Fermi bubbles + https://arxiv.org/abs/2507.20893 + arXiv:2507.20893v2 Announce Type: replace +Abstract: Despite their discovery fifteen years ago, the nature and origin of the Fermi bubbles remain unclear. We here investigate the effect a magnetic field can have on a subsonic breeze outflow emanating from the Galactic centre region. The presence of this magnetic field allows anisotropic diffusion of cosmic rays within the outflow, shaping the resultant cosmic ray distribution obtained out at large distances within the Galactic halo. We show that our magnetohydrodynamic Galactic breeze model, in combination with an opening angle for the injection of cosmic rays, leads to $\gamma$-ray emission from the Fermi bubble region with relatively sharp edges. + oai:arXiv.org:2507.20893v2 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - A. La Marca, M. T. Nardone, L. Wang, B. Margalef-Bentabol, S. Kruk, S. C. Trager + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Olivier Tourmente, Donna Rodgers-Lee, Andrew M. Taylor - Polarization Diagnostics Applied to Coronal Mass Ejections and the Background Solar Wind - https://arxiv.org/abs/2511.00714 - arXiv:2511.00714v2 Announce Type: replace -Abstract: The ratio of radially to tangentially polarized Thomson-scattered white light provides a powerful tool for locating the 3D position of compact structures in the solar corona and inner heliosphere, and the Polarimeter to Unify the Corona and Heliosphere (PUNCH) has been designed to take full advantage of this diagnostic capability. Interestingly, this same observable that establishes the position of transient blob-like structures becomes a local measure of the slope of the global falloff of density in the background solar wind. It is thus important to characterize the extent along the line of sight of structures being studied, in order to determine whether they are sufficiently compact for 3D positioning. In this paper, we build from analyses of individual lines of sight to three-dimensional models of coronal mass ejections (CMEs), allowing us to consider how accurately polarization properties of the transient and quiescent solar wind are diagnosed. In this way, we demonstrate the challenges and opportunities presented by PUNCH polarization data for various quantitative diagnostics. - oai:arXiv.org:2511.00714v2 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Group Therapy for Halos: Advancing Halo Mass Estimation for Galaxy Groups + https://arxiv.org/abs/2508.12556 + arXiv:2508.12556v3 Announce Type: replace +Abstract: Accurate estimation of dark matter halo masses for galaxy groups is central to studies of galaxy evolution and for leveraging group catalogues as cosmological probes. We present a calibration and evaluation of two complementary halo mass estimators: a dynamical estimator based on the virial theorem, and an empirical relation between the sum of the stellar masses of the three most massive group galaxies and the halo mass (SHMR). Using state-of-the-art semi-analytic models (SHARK, SAGE, and GAEA) to generate mock light-cone catalogues, we quantify the accuracy, uncertainty, and model dependence of each method. The calibrated virial theorem achieves negligible systematic bias (mean $\Delta$ = -0.01 dex) and low scatter (mean $\sigma$ = 0.20 dex) with no sensitivity to baryonic physics. The calibrated SHMR yields the highest precision (mean $\Delta$ = 0.02 dex, mean $\sigma$ = 0.14 dex) but shows greater model dependence due to sensitivity to baryonic physics across the models. We demonstrate applications to observational catalogues, including the empirical halo mass function and mapping quenched fractions in the stellar mass-halo mass plane. We provide guidance: the virial theorem is recommended for GAMA-like surveys (i < 19.2) at z < 0.1 where minimal model dependence is required, while the SHMR is optimal for high-precision halo mass estimates across diverse catalogues with limits of z < 0.3. These calibrated estimators will aid upcoming wide-area spectroscopic surveys in probing the connection between galaxies and their host dark matter halos. + oai:arXiv.org:2508.12556v3 + astro-ph.CO + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Sarah E Gibson, Craig E. DeForest, Curt A. de Koning, Steven R. Cranmer, Yuhong Fan, Huw Morgan, Elena Provornikova, Anna Malanushenko, David Webb + 10.1017/pasa.2026.10151 + Publications of the Astronomical Society of Australia. Published online 2026:1-18 + Welsey Van Kempen, Michelle E. Cluver, Edward N. Taylor, Darren J. Croton, Trystan S. Lambert, Claudia del P. Lagos - Limits of self-interacting neutrinos from the BAO and CMB phase shift - https://arxiv.org/abs/2511.00800 - arXiv:2511.00800v2 Announce Type: replace -Abstract: Neutrinos with Standard Model interactions free-stream in the early Universe, leaving a distinct phase shift in the pattern of baryon acoustic oscillations (BAO). When isolated, this phase shift allows one to robustly infer the presence of the cosmic neutrino background in BAO and cosmic microwave background (CMB) data independently of other cosmological parameters. While in the context of the Standard Model, this phase shift follows a known scale-dependent relation, new physics in the cosmic neutrino background could alter the overall shape of this feature. In this paper, we discuss how changes in the neutrino phase shift could be used to constrain self-interactions among neutrinos. We produce simple models for this phase-shift assuming universal self-interactions, and use these in order to understand what constraining power is available for the strength of such interactions in BAO and CMB data. We find that, although challenging, it may be possible to use a detection of the phase to put a more robust limit on the strength of the self-interaction, $G_{\mathrm{eff}}$, which at present suffers from bimodality in cosmological constraints. Our forecast analysis reveals that BAO data alone will not provide the precision needed to tightly constrain self-interactions; however, the combined analysis of the phase shift signature in both CMB and BAO can potentially provide a way to detect the impact of new neutrino interactions. Our results could be extended upon for models with non-universal interactions. - oai:arXiv.org:2511.00800v2 + One latent to fit them all: a unified representation of baryonic feedback on matter distribution + https://arxiv.org/abs/2509.01881 + arXiv:2509.01881v3 Announce Type: replace +Abstract: Accurate and parsimonious quantification of baryonic feedback on matter distribution is of crucial importance for understanding both cosmology and galaxy formation from observational data. This is, however, challenging given the large discrepancy among different models of galaxy formation simulations, and their distinct subgrid physics parameterizations. Using 5,072 simulations from 4 different models covering broad ranges in their parameter spaces, we find a unified 2D latent representation. Compared to the simulations and other phenomenological models, our representation is independent of both time and cosmology, much lower-dimensional, and disentangled in its impacts on the matter power spectra. The common latent space facilitates the comparison of parameter spaces of different models and is readily interpretable by correlation with each. The two latent dimensions provide a complementary representation of baryonic effects, linking black hole and supernova feedback to distinct and interpretable impacts on both the matter power spectrum, and field, level. Our approach enables developing robust and economical analytic models for optimal gain of physical information from data, and is generalizable to other fields with significant modeling uncertainty. + oai:arXiv.org:2509.01881v3 astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Abb\'e M. Whitford, Cullan Howlett, Tamara M. Davis, David Camarena, Francis-Yan Cyr-Racine - - - Uncertainties in the production of iron-group nuclides in core-collapse supernovae from Monte Carlo variations of reaction rates - https://arxiv.org/abs/2511.01859 - arXiv:2511.01859v3 Announce Type: replace -Abstract: Core-collapse supernovae, occurring at the end of massive star evolution, produce heavy elements, including those in the iron peak. Although the explosion mechanism is not yet fully understood, theoretical models can reproduce optical observations and observed elemental abundances. However, many nuclear reaction rates involved in explosive nucleosynthesis have large uncertainties, impacting the reliability of abundance predictions. To address this, we have previously developed a Monte Carlo-based nucleosynthesis code that accounts for reaction rate uncertainties and has been applied to nucleosynthesis processes beyond iron. Our framework is also well suited for studying explosive nucleosynthesis in supernovae. In this paper, we investigate 1D explosion models using the "PUSH method", focusing on progenitors with varying metallicities and initial masses around $M_\mathrm{ZAMS} = 16 M_{\odot}$. Detailed post-process nucleosynthesis calculations and Monte Carlo analyses are used to explore the effects of reaction rate uncertainties and to identify key reaction rates in explosive nucleosynthesis. We find that many reactions have little impact on the production of iron-group nuclei, as these elements are primarily synthesized in the nuclear statistical equilibrium. However, we identify a few "key reactions" that significantly influence the production of radioactive nuclei, which may affect astrophysical observables. In particular, for the production of ${}^{44}$Ti, we confirm that several traditionally studied nuclear reactions have a strong impact. However, determining a single reaction rate is insufficient to draw a definitive conclusion. - oai:arXiv.org:2511.01859v3 - astro-ph.SR - nucl-ex - nucl-th - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Nobuya Nishimura, Carla Froehlich, Thomas Rauscher + 10.3847/2041-8213/ae3084 + ApJL 996 L41 (2026) + Shurui Lin, Yin Li, Shy Genel, Francisco Villaescusa-Navarro, Biwei Dai, Wentao Luo, Yang Wang - Euclid Quick Data Release (Q1). Quenching precedes bulge formation in dense environments but follows it in the field - https://arxiv.org/abs/2511.02964 - arXiv:2511.02964v2 Announce Type: replace -Abstract: (Abridged) The bimodality between star-forming discs and quiescent spheroids requires the existence of two main processes: the galaxy quenching and the morphological transformation. In this paper, we aim to understand the link between these processes and their relation with the stellar mass of galaxies and their local environment. Taking advantage of the first data released by the Euclid Collaboration, covering more than 60 deg2 with space-based imaging and photometry, we analyse a mass-complete sample of nearly one million galaxies in the range 0.25<z<1 with $M_\ast>10^{9.5} M_\odot$. We divide the sample into four sub-populations of galaxies, based on their star-formation activity and morphology. We then analyse the physical properties of these populations and their relative abundances in the stellar mass vs. local density plane. Together with confirming the passivity-density relation and the morphology-density relation, we find that quiescent discy galaxies are more abundant in the low-mass regime of high-density environment. At the same time, star-forming bulge-dominated galaxies are more common in field regions, preferentially at high masses. Building on these results and interpreting them through comparison with simulations, we propose a scenario where the evolution of galaxies in the field significantly differs from that in higher-density environments. The morphological transformation in the majority of field galaxies takes place before the onset of quenching and is mainly driven by secular processes taking place within the main sequence, leading to the formation of star-forming bulge-dominated galaxies as intermediate-stage galaxies. Conversely, quenching of star formation precedes morphological transformation for most galaxies in higher-density environments. This causes the formation of quiescent disc-dominated galaxies before their transition into bulge-dominated ones. - oai:arXiv.org:2511.02964v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Enhancing the detectability of ionized Regions during the Epoch of Reionization + https://arxiv.org/abs/2509.02148 + arXiv:2509.02148v2 Announce Type: replace +Abstract: We present an improved matched filter method for detecting large ionized regions in 21 cm observations of the Epoch of Reionization. In addition to detection, the method constrains the properties of these regions, offering insights into the underlying source populations. Extending a previously developed Bayesian framework, we replace the spherical filter with an eight-parameter spheroidal filter, enabling a more flexible characterization of ionized bubbles. This enhancement significantly improves both detectability and recovery of bubble orientations. For a representative reionization scenario with mean ionization fraction $0.4$ at $z=7$, we find that a $10\sigma$ detection of the largest ionized region can be achieved with $\sim 1$ h of observations using the SKA-low AA4 and AA$^{\star}$ layouts. Our method can help identify regions in the observed field that host large ionized bubbles, making them prime targets for deeper follow-up observations. + oai:arXiv.org:2509.02148v2 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Euclid Collaboration, F. Gentile (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), E. Daddi (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), D. Elbaz (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), A. Enia (Dipartimento di Fisica e Astronomia, Universit\`a di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), B. Magnelli (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), J-B. Billand (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France), P. Corcho-Caballero (Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands), C. Cleland (Universit\'e Paris Cit\'e, CNRS, Astroparticule et Cosmologie, 75013 Paris, France), G. De Lucia (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), C. D'Eugenio (Institute de Physique du Globe de Paris, 1 Rue Jussieu, 75005, Paris, CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France), M. Fossati (Dipartimento di Fisica "G. Occhialini", Universit\`a degli Studi di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy, INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), M. Franco (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), C. Lobo (Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto, Portugal, Departamento de F\'isica e Astronomia, Faculdade de Ci\^encias, Universidade do Porto, Rua do Campo Alegre 687, PT4169-007 Porto, Portugal), Y. Lyu (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France), M. Magliocchetti (INAF-Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere, 100, 00100 Roma, Italy), G. A. Mamon (Institut d'Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Universit\'e, 98 bis boulevard Arago, 75014 Paris, France, Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France), L. Quilley (Centre de Recherche Astrophysique de Lyon, UMR5574, CNRS, Universit\'e Claude Bernard Lyon 1, ENS de Lyon, 69230, Saint-Genis-Laval, France), J. G. Sorce (Univ. Lille, CNRS, Centrale Lille, UMR 9189 CRIStAL, 59000 Lille, France, Universit\'e Paris-Saclay, CNRS, Institut d'astrophysique spatiale, 91405, Orsay, France), M. Tarrasse (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France), M. Bolzonella (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), F. Durret (Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France), L. Gabarra (Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK), S. Guo (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France), L. Pozzetti (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Quai (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), F. Shankar (School of Physics \& Astronomy, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK), V. Sangalli (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France, Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), M. Talia (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), M. Baes (Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium), H. Fu (Center for Astronomy and Astrophysics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China, School of Physics \& Astronomy, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK), M. Girardi (Dipartimento di Fisica - Sezione di Astronomia, Universit\`a di Trieste, Via Tiepolo 11, 34131 Trieste, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), J. Matthee (Institute of Science and Technology Austria), P. A. Oesch (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland, Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen, Denmark), D. Roberts (School of Physics \& Astronomy, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK), J. Schaye (Leiden Observatory, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands), D. Scott (Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada), L. Spinoglio (INAF-Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere, 100, 00100 Roma, Italy), B. Altieri (ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), A. Amara (School of Mathematics and Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK), S. Andreon (INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), N. Auricchio (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), C. Baccigalupi (IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy), M. Baldi (Dipartimento di Fisica e Astronomia, Universit\`a di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), A. Balestra (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), S. Bardelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), R. Bender (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany, Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany), A. Biviano (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy), E. Branchini (Dipartimento di Fisica, Universit\`a di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), M. Brescia (Department of Physics "E. Pancini", University Federico II, Via Cinthia 6, 80126, Napoli, Italy, INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), J. Brinchmann (Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto, Portugal, Faculdade de Ci\^encias da Universidade do Porto, Rua do Campo de Alegre, 4150-007 Porto, Portugal, European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany), S. Camera (Dipartimento di Fisica, Universit\`a degli Studi di Torino, Via P. Giuria 1, 10125 Torino, Italy, INFN-Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy, INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese), G. Ca\~nas-Herrera (European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands, Leiden Observatory, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands), V. Capobianco (INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese), C. Carbone (INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy), J. Carretero (Centro de Investigaciones Energ\'eticas, Medioambientales y Tecnol\'ogicas, Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra), S. Casas (Institute for Theoretical Particle Physics and Cosmology, Deutsches Zentrum f\"ur Luft- und Raumfahrt e. V), M. Castellano (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), G. Castignani (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Cavuoti (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy, INFN section of Naples, Via Cinthia 6, 80126, Napoli, Italy), K. C. Chambers (Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA), A. Cimatti (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), C. Colodro-Conde (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Tenerife, Spain), G. Congedo (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), L. Conversi (European Space Agency/ESRIN, Largo Galileo Galilei 1, 00044 Frascati, Roma, Italy, ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), Y. Copin (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), F. Courbin (Institut de Ci\`encies del Cosmos, Instituci\'o Catalana de Recerca i Estudis Avan\c{c}ats), H. M. Courtois (UCB Lyon 1, CNRS/IN2P3, IUF, IP2I Lyon, 4 rue Enrico Fermi, 69622 Villeurbanne, France), M. Cropper (Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK), A. Da Silva (Departamento de F\'isica, Faculdade de Ci\^encias, Universidade de Lisboa, Edif\'icio C8, Campo Grande, PT1749-016 Lisboa, Portugal, Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Faculdade de Ci\^encias, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal), H. Degaudenzi (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), C. Dolding (Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK), H. Dole (Universit\'e Paris-Saclay, CNRS, Institut d'astrophysique spatiale, 91405, Orsay, France), F. Dubath (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), C. A. J. Duncan (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), X. Dupac (ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), S. Dusini (INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), S. Escoffier (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), M. Fabricius (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany, Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany), M. Farina (INAF-Istituto di Astrofisica e Planetologia Spaziali, via del Fosso del Cavaliere, 100, 00100 Roma, Italy), R. Farinelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Ferriol (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), F. Finelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy), N. Fourmanoit (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), M. Frailis (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), E. Franceschi (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), M. Fumana (INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy), S. Galeotta (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), B. Gillis (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), C. Giocoli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), J. Gracia-Carpio (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), A. Grazian (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), F. Grupp (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany, Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany), S. Gwyn (Herzberg Astronomy and Astrophysics Research Centre, 5071 W. Saanich Rd. Victoria, BC, V9E 2E7, Canada), S. V. H. Haugan (Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, 0315 Oslo, Norway), J. Hoar (ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), W. Holmes (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA), I. M. Hook (Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK), F. Hormuth (Felix Hormuth Engineering, Goethestr. 17, 69181 Leimen, Germany), A. Hornstrup (Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark, Cosmic Dawn Center), K. Jahnke (Max-Planck-Institut f\"ur Astronomie, K\"onigstuhl 17, 69117 Heidelberg, Germany), M. Jhabvala (NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA), B. Joachimi (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK), E. Keih\"anen (Department of Physics and Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), S. Kermiche (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), A. Kiessling (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA), B. Kubik (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), M. K\"ummel (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany), M. Kunz (Universit\'e de Gen\`eve, D\'epartement de Physique Th\'eorique and Centre for Astroparticle Physics, 24 quai Ernest-Ansermet, CH-1211 Gen\`eve 4, Switzerland), H. Kurki-Suonio (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland, Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), A. M. C. Le Brun (Laboratoire d'etude de l'Univers et des phenomenes eXtremes, Observatoire de Paris, Universit\'e PSL, Sorbonne Universit\'e, CNRS, 92190 Meudon, France), S. Ligori (INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese), P. B. Lilje (Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, 0315 Oslo, Norway), V. Lindholm (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland, Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), I. Lloro (SKAO, Jodrell Bank, Lower Withington, Macclesfield SK11 9FT, UK), G. Mainetti (Centre de Calcul de l'IN2P3/CNRS, 21 avenue Pierre de Coubertin 69627 Villeurbanne Cedex, France), D. Maino (Dipartimento di Fisica "Aldo Pontremoli", Universit\`a degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy, INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy, INFN-Sezione di Milano, Via Celoria 16, 20133 Milano, Italy), E. Maiorano (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), O. Mansutti (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), O. Marggraf (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), M. Martinelli (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy, INFN-Sezione di Roma, Piazzale Aldo Moro, 2 - c/o Dipartimento di Fisica, Edificio G. Marconi, 00185 Roma, Italy), N. Martinet (Aix-Marseille Universit\'e, CNRS, CNES, LAM, Marseille, France), F. Marulli (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), R. J. Massey (Department of Physics, Institute for Computational Cosmology, Durham University, South Road, Durham, DH1 3LE, UK), E. Medinaceli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Mei (Universit\'e Paris Cit\'e, CNRS, Astroparticule et Cosmologie, 75013 Paris, France, CNRS-UCB International Research Laboratory, Centre Pierre Bin\'etruy, IRL2007, CPB-IN2P3, Berkeley, USA), M. Melchior (University of Applied Sciences and Arts of Northwestern Switzerland, School of Engineering, 5210 Windisch, Switzerland), Y. Mellier (Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France, Institut d'Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Universit\'e, 98 bis boulevard Arago, 75014 Paris, France), M. Meneghetti (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), E. Merlin (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), G. Meylan (Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique F\'ed\'erale de Lausanne), A. Mora (Telespazio UK S.L. for European Space Agency), M. Moresco (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), L. Moscardini (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), R. Nakajima (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), S. -M. Niemi (European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands), C. Padilla (Institut de F\'isica d'Altes Energies), S. Paltani (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), F. Pasian (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), K. Pedersen (DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155, 2200 Copenhagen, Denmark), W. J. Percival (Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada), V. Pettorino (European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands), S. Pires (Universit\'e Paris-Saclay, Universit\'e Paris Cit\'e, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France), G. Polenta (Space Science Data Center, Italian Space Agency, via del Politecnico snc, 00133 Roma, Italy), M. Poncet (Centre National d'Etudes Spatiales -- Centre spatial de Toulouse, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France), L. A. Popa (Institute of Space Science, Str. Atomistilor, nr. 409 M\u{a}gurele, Ilfov, 077125, Romania), F. Raison (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), A. Renzi (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), J. Rhodes (Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA), G. Riccio (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), E. Romelli (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), M. Roncarelli (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), R. Saglia (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany, Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), Z. Sakr (Institut f\"ur Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany, Institut de Recherche en Astrophysique et Plan\'etologie, Universit\'e St Joseph, Faculty of Sciences, Beirut, Lebanon), D. Sapone (Departamento de F\'isica, FCFM, Universidad de Chile, Blanco Encalada 2008, Santiago, Chile), B. Sartoris (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), P. Schneider (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), T. Schrabback (Universit\"at Innsbruck, Institut f\"ur Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria), A. Secroun (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), G. Seidel (Max-Planck-Institut f\"ur Astronomie, K\"onigstuhl 17, 69117 Heidelberg, Germany), S. Serrano (Institut d'Estudis Espacials de Catalunya, Satlantis, University Science Park, Sede Bld 48940, Leioa-Bilbao, Spain, Institute of Space Sciences), P. Simon (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), C. Sirignano (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), G. Sirri (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), J. Skottfelt (Centre for Electronic Imaging, Open University, Walton Hall, Milton Keynes, MK7~6AA, UK), L. Stanco (INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), J. Steinwagner (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), P. Tallada-Cresp\'i (Centro de Investigaciones Energ\'eticas, Medioambientales y Tecnol\'ogicas, Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra), A. N. Taylor (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), H. I. Teplitz (Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA), I. Tereno (Departamento de F\'isica, Faculdade de Ci\^encias, Universidade de Lisboa, Edif\'icio C8, Campo Grande, PT1749-016 Lisboa, Portugal, Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Faculdade de Ci\^encias, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal), N. Tessore (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK), S. Toft (Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen, Denmark), R. Toledo-Moreo (Universidad Polit\'ecnica de Cartagena, Departamento de Electr\'onica y Tecnolog\'ia de Computadoras, Plaza del Hospital 1, 30202 Cartagena, Spain), F. Torradeflot (Port d'Informaci\'o Cient\'ifica, Campus UAB, C. Albareda s/n, 08193 Bellaterra, Centro de Investigaciones Energ\'eticas, Medioambientales y Tecnol\'ogicas), I. Tutusaus (Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Institut de Recherche en Astrophysique et Plan\'etologie), L. Valenziano (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy), J. Valiviita (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland, Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), T. Vassallo (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), G. Verdoes Kleijn (Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands), A. Veropalumbo (INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy, Dipartimento di Fisica, Universit\`a di Genova, Via Dodecaneso 33, 16146, Genova, Italy), Y. Wang (Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA), J. Weller (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany, Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), A. Zacchei (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy), G. Zamorani (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), I. A. Zinchenko (Astronomisches Rechen-Institut, Zentrum f\"ur Astronomie der Universit\"at Heidelberg, M\"onchhofstr. 12-14, 69120 Heidelberg, Germany), E. Zucca (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), V. Allevato (INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy), M. Ballardini (Dipartimento di Fisica e Scienze della Terra, Universit\`a degli Studi di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy, Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), E. Bozzo (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), C. Burigana (INAF, Istituto di Radioastronomia, Via Piero Gobetti 101, 40129 Bologna, Italy, INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy), R. Cabanac (Institut de Recherche en Astrophysique et Plan\'etologie), M. Calabrese (Astronomical Observatory of the Autonomous Region of the Aosta Valley, INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy), A. Cappi (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, Universit\'e C\^ote d'Azur, Observatoire de la C\^ote d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, 06304 Nice cedex 4, France), D. Di Ferdinando (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), J. A. Escartin Vigo (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany), W. G. Hartley (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), M. Huertas-Company (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Tenerife, Spain, Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Universidad de La Laguna, Dpto. Astrof\'i sica, E-38206 La Laguna, Tenerife, Spain, Universit\'e PSL, Observatoire de Paris, Sorbonne Universit\'e, CNRS, LERMA, 75014, Paris, France, Universit\'e Paris-Cit\'e, 5 Rue Thomas Mann, 75013, Paris, France), J. Mart\'in-Fleitas (Aurora Technology for European Space Agency), S. Matthew (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), N. Mauri (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), R. B. Metcalf (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), A. Pezzotta (INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), M. P\"ontinen (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland), I. Risso (INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy), V. Scottez (Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France, ICL, Junia, Universit\'e Catholique de Lille, LITL, 59000 Lille, France), M. Sereno (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), M. Tenti (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), M. Viel (IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, ICSC - Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy), M. Wiesmann (Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, 0315 Oslo, Norway), Y. Akrami (Instituto de F\'isica Te\'orica UAM-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain, CERCA/ISO, Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA), I. T. Andika (Technical University of Munich, TUM School of Natural Sciences, Physics Department, James-Franck-Str. 1, 85748 Garching, Germany, Max-Planck-Institut f\"ur Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany), S. Anselmi (INFN-Padova, Via Marzolo 8, 35131 Padova, Italy, Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, Laboratoire Univers et Th\'eorie, Observatoire de Paris, Universit\'e PSL, Universit\'e Paris Cit\'e, CNRS, 92190 Meudon, France), M. Archidiacono (Dipartimento di Fisica "Aldo Pontremoli", Universit\`a degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy, INFN-Sezione di Milano, Via Celoria 16, 20133 Milano, Italy), F. Atrio-Barandela (Departamento de F\'isica Fundamental. Universidad de Salamanca. Plaza de la Merced s/n. 37008 Salamanca, Spain), D. Bertacca (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), M. Bethermin (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), L. Bisigello (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), A. Blanchard (Institut de Recherche en Astrophysique et Plan\'etologie), L. Blot (Center for Data-Driven Discovery, Kavli IPMU, Laboratoire d'etude de l'Univers et des phenomenes eXtremes, Observatoire de Paris, Universit\'e PSL, Sorbonne Universit\'e, CNRS, 92190 Meudon, France), H. B\"ohringer (Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany, University Observatory, LMU Faculty of Physics, Scheinerstr. 1, 81679 Munich, Germany, Max-Planck-Institut f\"ur Physik, Boltzmannstr. 8, 85748 Garching, Germany), M. Bonici (Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy), S. Borgani (Dipartimento di Fisica - Sezione di Astronomia, Universit\`a di Trieste, Via Tiepolo 11, 34131 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, ICSC - Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy), M. L. Brown (Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK), S. Bruton (California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA), A. Calabro (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), B. Camacho Quevedo (IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy), F. Caro (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), C. S. Carvalho (Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Faculdade de Ci\^encias, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal), T. Castro (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, ICSC - Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy), F. Cogato (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), S. Conseil (Universit\'e Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, Villeurbanne, F-69100, France), T. Contini (Institut de Recherche en Astrophysique et Plan\'etologie), A. R. Cooray (Department of Physics \& Astronomy, University of California Irvine, Irvine CA 92697, USA), O. Cucciati (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), G. Desprez (Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands), A. D\'iaz-S\'anchez (Departamento F\'isica Aplicada, Universidad Polit\'ecnica de Cartagena, Campus Muralla del Mar, 30202 Cartagena, Murcia, Spain), S. Di Domizio (Dipartimento di Fisica, Universit\`a di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy), J. M. Diego (Instituto de F\'isica de Cantabria, Edificio Juan Jord\'a, Avenida de los Castros, 39005 Santander, Spain), P. Dimauro (Observatorio Nacional, Rua General Jose Cristino, 77-Bairro Imperial de Sao Cristovao, Rio de Janeiro, 20921-400, Brazil, INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), P. -A. Duc (Universit\'e de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France), M. Y. Elkhashab (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, Dipartimento di Fisica - Sezione di Astronomia, Universit\`a di Trieste, Via Tiepolo 11, 34131 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy), Y. Fang (Universit\"ats-Sternwarte M\"unchen, Fakult\"at f\"ur Physik, Ludwig-Maximilians-Universit\"at M\"unchen, Scheinerstr. 1, 81679 M\"unchen, Germany), A. Finoguenov (Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland), A. Fontana (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), F. Fontanot (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy), A. Franco (INFN, Sezione di Lecce, Via per Arnesano, CP-193, 73100, Lecce, Italy, Department of Mathematics and Physics E. De Giorgi, University of Salento, Via per Arnesano, CP-I93, 73100, Lecce, Italy, INAF-Sezione di Lecce, c/o Dipartimento Matematica e Fisica, Via per Arnesano, 73100, Lecce, Italy), K. Ganga (Universit\'e Paris Cit\'e, CNRS, Astroparticule et Cosmologie, 75013 Paris, France), J. Garc\'ia-Bellido (Instituto de F\'isica Te\'orica UAM-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain), T. Gasparetto (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), V. Gautard (CEA Saclay, DFR/IRFU, Service d'Astrophysique, Bat. 709, 91191 Gif-sur-Yvette, France), R. Gavazzi (Aix-Marseille Universit\'e, CNRS, CNES, LAM, Marseille, France, Institut d'Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Universit\'e, 98 bis boulevard Arago, 75014 Paris, France), E. Gaztanaga (Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, UK), F. Giacomini (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), F. Gianotti (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), A. H. Gonzalez (Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611, USA), G. Gozaliasl (Department of Computer Science, Aalto University, PO Box 15400, Espoo, FI-00 076, Finland, Department of Physics, P.O. Box 64, University of Helsinki, 00014 Helsinki, Finland), M. Guidi (Dipartimento di Fisica e Astronomia, Universit\`a di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), C. M. Gutierrez (Instituto de Astrof\'isica de Canarias, E-38205 La Laguna, Universidad de La Laguna, Dpto. Astrof\'i sica, E-38206 La Laguna, Tenerife, Spain), A. Hall (Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK), S. Hemmati (Caltech/IPAC, 1200 E. California Blvd., Pasadena, CA 91125, USA), H. Hildebrandt (Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute), J. Hjorth (DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155, 2200 Copenhagen, Denmark), J. J. E. Kajava (Department of Physics and Astronomy, Vesilinnantie 5, University of Turku, 20014 Turku, Finland, Serco for European Space Agency), Y. Kang (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), V. Kansal (ARC Centre of Excellence for Dark Matter Particle Physics, Melbourne, Australia, Centre for Astrophysics \& Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia), D. Karagiannis (Dipartimento di Fisica e Scienze della Terra, Universit\`a degli Studi di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy, Department of Physics and Astronomy, University of the Western Cape, Bellville, Cape Town, 7535, South Africa), K. Kiiveri (Department of Physics and Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), J. Kim (Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK), C. C. Kirkpatrick (Department of Physics and Helsinki Institute of Physics, Gustaf H\"allstr\"omin katu 2, University of Helsinki, 00014 Helsinki, Finland), S. Kruk (ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain), L. Legrand (DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA, UK, Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge, CB3 0HA, UK), M. Lembo (Institut d'Astrophysique de Paris, UMR 7095, CNRS, and Sorbonne Universit\'e, 98 bis boulevard Arago, 75014 Paris, France, Dipartimento di Fisica e Scienze della Terra, Universit\`a degli Studi di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy, Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, Via Giuseppe Saragat 1, 44122 Ferrara, Italy), F. Lepori (Department of Astrophysics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland), G. Leroy (Department of Physics, Centre for Extragalactic Astronomy, Durham University, South Road, Durham, DH1 3LE, UK, Department of Physics, Institute for Computational Cosmology, Durham University, South Road, Durham, DH1 3LE, UK), G. F. Lesci (Dipartimento di Fisica e Astronomia "Augusto Righi" - Alma Mater Studiorum Universit\`a di Bologna, via Piero Gobetti 93/2, 40129 Bologna, Italy, INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), J. Lesgourgues (Institute for Theoretical Particle Physics and Cosmology), L. Leuzzi (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), T. I. Liaudat (IRFU, CEA, Universit\'e Paris-Saclay 91191 Gif-sur-Yvette Cedex, France), A. Loureiro (Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, Stockholm, SE-106 91, Sweden, Astrophysics Group, Blackett Laboratory, Imperial College London, London SW7 2AZ, UK), J. Macias-Perez (Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC-IN2P3, 53, Avenue des Martyrs, 38000, Grenoble, France), E. A. Magnier (Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA), F. Mannucci (INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy), R. Maoli (Dipartimento di Fisica, Sapienza Universit\`a di Roma, Piazzale Aldo Moro 2, 00185 Roma, Italy, INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy), C. J. A. P. Martins (Centro de Astrof\'isica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal, Instituto de Astrof\'isica e Ci\^encias do Espa\c{c}o, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto, Portugal), L. Maurin (Universit\'e Paris-Saclay, CNRS, Institut d'astrophysique spatiale, 91405, Orsay, France), M. Miluzio (ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Ca\~nada, Madrid, Spain, HE Space for European Space Agency), P. Monaco (Dipartimento di Fisica - Sezione di Astronomia, Universit\`a di Trieste, Via Tiepolo 11, 34131 Trieste, Italy, INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, ICSC - Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy), C. Moretti (INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy, IFPU, Institute for Fundamental Physics of the Universe, via Beirut 2, 34151 Trieste, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy), G. Morgante (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), K. Naidoo (Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, UK, Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK), A. Navarro-Alsina (Universit\"at Bonn, Argelander-Institut f\"ur Astronomie, Auf dem H\"ugel 71, 53121 Bonn, Germany), S. Nesseris (Instituto de F\'isica Te\'orica UAM-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain), D. Paoletti (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy, INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy), F. Passalacqua (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), K. Paterson (Max-Planck-Institut f\"ur Astronomie, K\"onigstuhl 17, 69117 Heidelberg, Germany), L. Patrizii (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), A. Pisani (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), D. Potter (Department of Astrophysics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland), M. Radovich (INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), G. Rodighiero (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INAF-Osservatorio Astronomico di Padova, Via dell'Osservatorio 5, 35122 Padova, Italy), S. Sacquegna (INAF - Osservatorio Astronomico d'Abruzzo, Via Maggini, 64100, Teramo, Italy, Department of Mathematics and Physics E. De Giorgi, University of Salento, Via per Arnesano, CP-I93, 73100, Lecce, Italy, INFN, Sezione di Lecce, Via per Arnesano, CP-193, 73100, Lecce, Italy), M. Sahl\'en (Theoretical astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, 751 37 Uppsala, Sweden), D. B. Sanders (Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA), E. Sarpa (SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste TS, Italy, ICSC - Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy, INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste TS, Italy), C. Scarlata (Minnesota Institute for Astrophysics, University of Minnesota, 116 Church St SE, Minneapolis, MN 55455, USA), A. Schneider (Department of Astrophysics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland), M. Schultheis (Universit\'e C\^ote d'Azur, Observatoire de la C\^ote d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, 06304 Nice cedex 4, France), D. Sciotti (INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy, INFN-Sezione di Roma, Piazzale Aldo Moro, 2 - c/o Dipartimento di Fisica, Edificio G. Marconi, 00185 Roma, Italy), E. Sellentin (Mathematical Institute, University of Leiden, Einsteinweg 55, 2333 CA Leiden, The Netherlands, Leiden Observatory, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands), L. C. Smith (Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK), S. A. Stanford (Department of Physics and Astronomy, University of California, Davis, CA 95616, USA), K. Tanidis (Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK), G. Testera (INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy), R. Teyssier (Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544, USA), S. Tosi (Dipartimento di Fisica, Universit\`a di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy, INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy), A. Troja (Dipartimento di Fisica e Astronomia "G. Galilei", Universit\`a di Padova, Via Marzolo 8, 35131 Padova, Italy, INFN-Padova, Via Marzolo 8, 35131 Padova, Italy), M. Tucci (Department of Astronomy, University of Geneva, ch. d'Ecogia 16, 1290 Versoix, Switzerland), C. Valieri (INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy), A. Venhola (Space physics and astronomy research unit, University of Oulu, Pentti Kaiteran katu 1, FI-90014 Oulu, Finland), D. Vergani (INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy), G. Verza (Center for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, 10010, New York, NY, USA), P. Vielzeuf (Aix-Marseille Universit\'e, CNRS/IN2P3, CPPM, Marseille, France), N. A. Walton (Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK) + Rutvik Ashish Mahajan, Raghunath Ghara, Nishant Pradeep Deo, Arnab Mishra - Artificial Precision Polarization Array: Sensitivity for the axion-like dark matter with clock satellites - https://arxiv.org/abs/2511.04400 - arXiv:2511.04400v2 Announce Type: replace -Abstract: The approaches to searching for axion-like signals based on pulsars include observations with pulsar timing arrays (PTAs) and pulsar polarization arrays (PPAs). However, these methods are limited by observational uncertainties arising from multiple unknown and periodic physical effects, which substantially complicate subsequent data analysis. To mitigate these issues and improve data fidelity, we propose the Artificial Pulsar Polarization Arrays (APPA): a satellite network comprising multiple pulsed signal transmitters and a dedicated receiver satellite. To constrain the axion-photon coupling parameter $g_{a\gamma}$, we generate simulated observations using Monte Carlo methods and investigate the sensitivity of APPA using two complementary approaches: Likelihood analysis and frequentist analysis. Simulations indicate that for the axion mass range of $10^{-22}-10^{-18}$ eV, APPA yields a tighter upper limit on $g_{a\gamma}$ (at the 95\% confidence level) than conventional ground-based observations, while also achieving superior detection sensitivity. Moreover, a larger spatial distribution scale of the satellite network corresponds to a greater advantage in detecting axions with lighter masses. - oai:arXiv.org:2511.04400v2 - astro-ph.CO - astro-ph.IM - gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 + Multi-color characterization of optically invisible FU Orionis-type outbursts: Demonstration and prospects for the WINTER survey + https://arxiv.org/abs/2509.04560 + arXiv:2509.04560v2 Announce Type: replace +Abstract: Episodic mass accretion is the dominant mechanism for mass assembly in the proto-stellar phase. Although prior optical time-domain searches have allowed detailed studies of individual outbursts, these searches remain insensitive to the earliest stages of star formation. In this paper, we present the characterization of two FU Orionis (FUor) outbursts identified using the combination of the ground-based, near-infrared Wide-field Infrared Transient Explorer (WINTER) and the space-based, mid-infrared NEOWISE survey. Supplemented with near-infrared spectroscopic follow-up, we show that both objects are bona fide FUor type outbursts based on i) their proximity to star-forming regions, ii) large amplitude (2-4 magnitudes) infrared brightening over the last decade, iii) progenitor colors consistent with embedded (Class I) protostars, and iv) "mixed-temperature" infrared spectra exhibiting characteristic signatures of cool outer envelopes and a hot inner disk with a wind. While one source, WNTR24-cua, is a known FUor which we independently recover; the second source, WNTR24-egv, is a newly confirmed object. Neither source is detected in contemporaneous ground-based optical imaging, despite flux limits $\gtrsim 100\times$ fainter than their infrared brightness, demonstrating the capabilities of WINTER to identify heavily obscured young stellar object (YSO) outbursts. We highlight the capabilities of the Galactic Plane survey of the recently commissioned WINTER observatory in addressing the poorly understood FUor population with its unique combination of real-time detection capabilities, multi-color sensitivity, weekly cadence, and wide area coverage. + oai:arXiv.org:2509.04560v2 + astro-ph.SR + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hanyu Jiang, Baoyu Xu, Yun-Long Zhang + Danielle Frostig, Kishalay De, Lynne A. Hillenbrand, Jill Juneau, Viraj R. Karambelkar, Mansi M. Kasliwal, Nathan P. Lourie, Geoffrey Mo, Sam Rose, Robert A. Simcoe, Robert D. Stein - Historical Surveys to Rubin First Look: Absolute Colors of trans-Neptunian objects - https://arxiv.org/abs/2511.10782 - arXiv:2511.10782v2 Announce Type: replace -Abstract: We present a comprehensive photometric study of transNeptunian objects (TNOs) by combining data from SDSS, Col-OSSOS, DES, and the recent Rubin First Look (RFL) data. Our database comprises 43 878 measurements in the u, g, r, i, z, and J filters, from which we derived 8 738 phase curves for 1 921 unique objects. - From these data, we computed 12 852 absolute color measurements and spectral slope differences for 1 761 objects, allowing a statistical characterization of phase coloring effects. The colors show no strong bimodality or correlation with orbital parameters, emphasizing the importance of phase correction even for small phase angles. The increase in sample size and application of phase corrections fill previously empty regions in color magnitude space likely affected by observational biases, as redder (and thus darker) objects are preferentially lost near detection limits. - Notably, our dataset includes the first photometric measurements from Rubin Observatory during RFL, covering eight objects (five newly discovered TNOs and three previously known). These early LSST observations occupy sparsely sampled regions of parameter space, particularly at faint magnitudes, highlighting the discovery and characterization potential of the full survey. - We confirm previous results showing that TNO colors vary with phase angle, exhibiting both reddening and bluening trends. Correlations between (dS'/dalpha) and (alpha) strengthen with increasing (Delta lambda), except for Hi - Hz, which tends to neutralize, consistent with the spectral flattening previously reported in visible wavelengths. - oai:arXiv.org:2511.10782v2 - astro-ph.EP - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Rapid jet production and suppression during fast state transitions in the black hole X-ray binary MAXI J1348$-$630 + https://arxiv.org/abs/2509.06487 + arXiv:2509.06487v2 Announce Type: replace +Abstract: Black hole X-ray binaries (BH XRBs) launch powerful relativistic jets during bright outburst phases. The properties of these outflows change dramatically between different spectral/accretion states. Compact jets are observed during the hard state and are quenched during the soft state, while discrete ejecta are mainly launched during the hard-to-soft state transition. Currently, we do not understand what triggers the formation/destruction of compact jets or the launch of discrete ejecta. In this context, finding a unique link between the jet evolution and the properties of the X-ray emission, such as its fast variability, would imply major progress in our understanding of the fundamental mechanisms that drive relativistic outflows in BH XRBs. Here we show that a brief, strong radio re-brightening during a predominantly soft state of the BH XRB MAXI J1348$-$630 was contemporaneous with a significant increase in the X-ray rms variability observed with NICER in 2019. During this phase, the variability displayed significant changes and, at the same time, MAXI J1348$-$630 launched two relativistic discrete ejecta that we detected with the MeerKAT and ATCA radio-interferometers. We propose that short-lived compact jets were reactivated during this excursion to the hard-intermediate state and were switched off before the ejecta launch, a behavior that has been very rarely observed in these systems. Interestingly, with the caveat of gaps in our radio and X-ray coverage, we suggest a tentative correspondence between the launch of ejecta and the drop in X-ray rms variability in this source, while other typical X-ray signatures associated with discrete ejections are not detected. We discuss how these results provide us with insights into the complex dynamic coupling between the jets and hot corona in BH XRBs. + oai:arXiv.org:2509.06487v2 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Milagros Colazo, Alvaro Alvarez-Candal + Francesco Carotenuto, Liang Zhang, Diego Altamirano, Piergiorgio Casella, St\'ephane Corbel, James C. A. Miller-Jones - Electron Cyclotron Maser Emission as the Driving Mechanism in Long-Period Radio Transients - https://arxiv.org/abs/2511.15154 - arXiv:2511.15154v2 Announce Type: replace -Abstract: Long-period radio transients (LPRTs) are highly polarised, coherent radio sources with periods of minutes to hours and bursts typically lasting 10 to 100 s. Here we consider the apparently isolated subclass of LPRTs and argue that electron cyclotron maser emission (ECME) explains their narrow duty cycles and polarisation properties. In particular, we show that intrinsically circular ECME can emerge as predominantly linear after undergoing Faraday conversion in an overlying magnetospheric plasma layer, thus reconciling the observed high linear fractions with a circularly polarised maser. In this picture, a rotating oblique magnetosphere beams radiation into a thin, hollow emission cone whose surface lies almost perpendicular to the local magnetic field. The observed very narrow pulses arise when the line of sight skims the cone, while broader profiles and weak leading or trailing components occur when multiple azimuths along the emission ring meet the maser resonance condition. The observed isotropic-equivalent luminosities of about 10^30 to 10^31 erg s^-1 correspond to modest intrinsic powers once strong ECME beaming is taken into account. We show that such power levels can be supplied by accretion from the interstellar medium (ISM), and that detectability at kiloparsec distances favours slowly rotating neutron stars with comparatively low surface magnetic fields below about 10^10 Gauss and low space velocities. - oai:arXiv.org:2511.15154v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + STRAWBERRY: Finding haloes in the gravitational potential + https://arxiv.org/abs/2509.11993 + arXiv:2509.11993v2 Announce Type: replace +Abstract: Here, we present a novel algorithm that discriminates between bound and unbound particles by consideration of the gravitational potential from an accelerated reference frame -- also referred to as `the boosted potential'. Particles are considered bound if their energy does not exceed the escape energy of a potential well -- given by the closest saddle-point that connects to a deeper potential minimum. This approach has core benefits over previous approaches, since it does not require any ad-hoc thresholds (such as over-density criteria), it includes the gravitational effect of all particles in the binding criterion (improving over widely used self-potential binding checks) and it only operates with instantaneous information (making it simpler than approaches based on dynamical histories). We show that particles typically become bound between their first peri- and apo-centeric passage and that bound and unbound populations show very distinct characteristics through their distribution in phase space, their density profiles, their virial ratios, and their redshift evolution. Our findings suggest that it is possible to understand haloes as two-component systems, with one component being bound, virialized, of finite extent and evolving slowly in quasi-equilibrium and the other component being unbound, unvirialized and evolving rapidly. + oai:arXiv.org:2509.11993v2 + astro-ph.CO + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Lilia Ferrario + http://creativecommons.org/licenses/by/4.0/ + Tamara R. G. Richardson, Jens St\"ucker, Raul E. Angulo - Explosions in the Empty: A Survey of Transients in Local Void Galaxies - https://arxiv.org/abs/2511.15401 - arXiv:2511.15401v2 Announce Type: replace -Abstract: We present a systematic analysis of transient astrophysical events -- including supernovae (SNe), gamma-ray bursts (GRBs), and fast radio bursts (FRBs) -- in void and non-void galaxies within the local universe ($0.005 < z < 0.05$). Cosmic voids, defined by low galaxy densities and characterized by minimal environmental interactions, offer a natural laboratory for isolating the impact of large-scale underdensities on stellar evolution and transient production. Using multi-wavelength data from the Sloan Digital Sky Survey, the Sternberg Astronomical Institute Supernova Catalogue, and high-energy space observatories, we compare transient occurrence rates and host galaxy properties across environments. We find that core-collapse supernovae (CCSNe) are significantly more common in void galaxies, indicating that massive star formation remains active in underdense regions. In contrast, Type Ia supernovae are less frequent in voids, consistent with a scarcity of older stellar populations. Notably, we identify a short-duration GRB hosted by a void galaxy, demonstrating that compact object mergers can occur in isolated environments. Additionally, we find no FRBs associated with void galaxies. Taken together, these results show that cosmic voids exert a measurable influence on the star formation history of galaxies and hence on the production of transients. - oai:arXiv.org:2511.15401v2 + Probing the millisecond pulsar origin of the $\gamma$-ray excess in the Galactic centre with LISA + https://arxiv.org/abs/2509.12998 + arXiv:2509.12998v2 Announce Type: replace +Abstract: The gigaelectronvolt $\gamma$-ray excess observed towards the Galactic centre remains unexplained. While dark matter annihilation has long been considered a leading explanation, an alternative scenario involving a large population of millisecond pulsars remains viable. Testing this hypothesis with electromagnetic observations is difficult, as pulsar searches in the bulge are strongly affected by interstellar scattering, high sky temperature, and source confusion. We investigate whether gravitational-wave observations with the Laser Interferometer Space Antenna (LISA) could provide an independent probe of the millisecond pulsar binary population in the Galactic bulge in the future. + We constructed synthetic populations of detached millisecond pulsar-white dwarf binaries under two illustrative formation scenarios: an accreted scenario, in which systems are deposited by disrupted globular clusters, and an in situ scenario, in which binaries form through isolated binary evolution. In both cases, only $10^{-5}$-$10^{-4}$ of the underlying bulge population is detectable by LISA. Still, even a few detections would imply tens to hundreds of thousands of unseen systems. Accreted binaries are expected to have lower chirp masses ($\sim$0.4 M$_\odot$), while in situ binaries produce more massive companions ($\sim$0.9 M$_\odot$), though part of this contrast reflects our modelling assumptions. LISA will measure binary frequencies with high precision, but chirp masses can only be determined for the most massive or highest-frequency systems. Thus, identifying millisecond-pulsar binaries among the far more numerous double white dwarfs will be challenging, as their gravitational-wave signals alone are indistinguishable. However, coordinated follow-up with the Square Kilometre Array of LISA-selected targets could directly test the millisecond-pulsar explanation of the $\gamma$-ray excess. + oai:arXiv.org:2509.12998v2 astro-ph.HE - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.CO + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3847/1538-4357/ae21e3 - ApJ 997 121 (2026) - Suo-Ning Wang, Bin-Bin Zhang, Rub\'en Garc\'ia-Benito + 10.1051/0004-6361/202557265 + A&A 705, A154 (2026) + Valeriya Korol, Andrei Igoshev - Absorption effects in the expanding Universe: spectral transmittance functions of intergalactic medium for distant sources - https://arxiv.org/abs/2511.16291 - arXiv:2511.16291v2 Announce Type: replace -Abstract: We analyse the formation of broad absorption troughs in the spectra of high-redshift sources in the redshift range $5\le z\le15$ for two observationally motivated reionization histories inferred from distant galaxy spectra and CMB polarization measurements. We assume that neutral hydrogen and helium in a homogeneous intergalactic medium are predominantly in their ground states and absorb radiation from distant sources through the Lyman-series lines and continua of HI, HeI, and HeII. We compute the wavelength-dependent optical depths in the first 40 Lyman-series lines of HI and HeII, in the first 10 Lyman-series lines of HeI, as well as in the corresponding Lyman continua, and use them to derive spectral transmittance functions of the intergalactic medium, $S(\lambda;z)$. We show that spectral features in the continuous spectra of sources at $5\lesssim z\lesssim7$ are particularly sensitive to the reionization histories of both hydrogen and helium. We present a compact analytic prescription for the effective intergalactic spectral transmittance caused by hydrogen and helium absorption over the redshift range $0\le z\le15$. The formalism provides closed-form expressions for the wavelength-dependent transmission of the intergalactic medium, including the Lyman-series transitions and continua of HI, HeI, and HeII, calibrated to observationally constrained reionization histories. - oai:arXiv.org:2511.16291v2 + The effect of matter discreteness on gravitational wave propagation in post-geometrical optics + https://arxiv.org/abs/2509.13884 + arXiv:2509.13884v2 Announce Type: replace +Abstract: The gravitational wave equation of motion includes direct coupling to the Riemann tensor. The curvature terms are usually neglected, but they can be large at the location of matter particles and impact the angular diameter distance. We apply the recently introduced post-geometrical optics approximation that includes curvature to gravitational wave propagation. Assuming that particles are localised within their Compton wavelength, the curvature due to electrons leads to a large effect on the angular diameter distance, but caustic formation invalidates the post-geometrical optics approximation. We conclude that the interesting regime of validity of the approximation is limited, as it ceases to apply when the curvature effects become large. Other methods are needed to evaluate the effect of curvature spikes, and the localisation of particles due to decoherence also needs further work. + oai:arXiv.org:2509.13884v2 astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Anguohao Yang, Bohdan Novosyadlyj, Pavlo Kopach, Bohdan Melekh, Gennadii Milinevsky + 10.1088/1475-7516/2026/01/030 + JCAP01(2026)030 + Sena Atli, Syksy Rasanen - JWST COMPASS: Insights into the Systematic Noise Properties of NIRSpec/G395H From a Uniform Reanalysis of Seven Transmission Spectra - https://arxiv.org/abs/2511.18196 - arXiv:2511.18196v2 Announce Type: replace -Abstract: JWST has already observed near-infrared transmission spectra of over a dozen super-Earths and sub-Neptunes. While some observations have allowed astronomers to characterize sub-Neptunes in unprecedented detail, small feature amplitudes and poorly-understood systematics have led to ambiguous results for others. Using the first seven targets from the COMPASS program, which is currently surveying 12 small planet atmospheres using NIRSpec/G395H, we investigate these timeseries systematics. We implement a model that uses the principle components of the normalized pixel fluxes to account for variations in the shape and position of the spectral trace. We find that observations with a smaller number of groups-per-integration benefit most profoundly from the use of this model, and that systematics are particularly strong between 2.8 and 3.5 $\mu$m. Despite these systematics, \texttt{pandexo} is a relatively accurate predictor of the precision of the spectra, with real error bars on average 5\% larger in NRS1 and 12\% larger in NRS2 than predicted. We compute new limits on metallicity and opaque pressure level for each target and compare these to previous results from the COMPASS program. Next, we co-add spectra from multiple targets to reduce the effective noise in the combined spectra in hopes of detecting transmission features in common between the targets, but this exercise does not yield compelling evidence any signals. We find that a handful of additional transits are sufficient to break the degeneracy between metallicity and aerosols for the majority of our targets, pointing towards the possibility of unraveling the mysteries of these worlds with future allocations of JWST time. - oai:arXiv.org:2511.18196v2 - astro-ph.EP + Polarimeter to Unify the Corona and Heliosphere (PUNCH) + https://arxiv.org/abs/2509.15131 + arXiv:2509.15131v2 Announce Type: replace +Abstract: The Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission is a NASA Small Explorer to determine the cross-scale processes that unify the solar corona and heliosphere. PUNCH has two science objectives: (1) understand how coronal structures become the ambient solar wind, and (2) understand the dynamic evolution of transient structures, such as coronal mass ejections, in the young solar wind. To address these objectives, PUNCH uses a constellation of four small spacecraft in Sun-synchronous low Earth orbit, to collect linearly polarized images of the K corona and young solar wind. The four spacecraft each carry one visible-light imager in a 1+3 configuration: a single Narrow Field Imager solar coronagraph captures images of the outer corona at all position angles, and at solar elongations from 1.5 degrees (6 R$_\odot$) to 8 degrees (32 R$_\odot$); and three separate Wide Field Imager heliospheric imagers together capture views of the entire inner solar system, at solar elongations from 3 degrees (12 R$_\odot$) to 45 degrees (180 R$_\odot$) from the Sun. PUNCH images include linear-polarization data, to enable inferring the three-dimensional structure of visible features without stereoscopy. The instruments are matched in wavelength passband, support overlapping instantaneous fields of view, and are operated synchronously, to act as a single ``virtual instrument'' with a 90 degree wide field of view, centered on the Sun. PUNCH launched in March of 2025 and began science operations in June of 2025. PUNCH has an open data policy with no proprietary period, and PUNCH Science Team Meetings are open to all. + oai:arXiv.org:2509.15131v2 + astro-ph.SR astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Tyler A. Gordon, Natalie M. Batalha, Natasha E. Batalha, Artyom Aguichine, Anna Gagnebin, James Kirk, Mercedes Lopez-Morales, Annabella Meech, Nicholas Scarsdale, Johanna Teske, Nicole L. Wallack, Nicholas Wogan + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Craig E. DeForest, Sarah E. Gibson, Ronnie Killough, Nick R. Waltham, Matt N. Beasley, Robin C. Colaninno, Glenn T. Laurent, Daniel B. Seaton, J. Marcus Hughes, Madhulika Guhathakurta, Nicholeen M. Viall, Raphael Attie, Dipankar Banerjee, Luke Barnard, Doug A. Biesecker, Mario M. Bisi, Volker Bothmer, Antonina Brody, Joan Burkepile, Iver H. Cairns, Jennifer L. Campbell, Traci Case, Amir Caspi, David Cheney, Rohit Chhiber, Matthew J. Clapp, Steven R. Cranmer, Jackie A. Davies, Curt A. de Koning, Mihir I. Desai, Heather A. Elliott, Samaiyah Farid, Bea Gallardo-Lacourt, Chris Gilly, Caden Gobat, Mary H. Hanson, Richard A. Harrison, Donald M. Hassler, Chase Henley, Alan M. Henry, Russell A. Howard, Bernard V. Jackson, Samuel Jones, Don Kolinski, Derek A. Lamb, Florine Lehtinen, Chris Lowder, Anna Malanushenko, William H. Matthaeus, David J. McComas, Jacob McGee, Huw Morgan, Divya Oberoi, Dusan Odstrcil, Chris Parmenter, Ritesh Patel, Francesco Pecora, Steve Persyn, Victor J. Pizzo, Simon P. Plunkett, Elena Provornikova, Nour Eddine Raouafi, Jillian A. Redfern, Alexis P. Rouillard, Kelly D. Smith, Keith B. Smith, Zachary S. Talpas, S. James Tappin, Arnaud Thernisien, Barbara J. Thompson, Samuel Van Kooten, Kevin J. Walsh, David F. Webb, William L. Wells, Matthew J. West, Zachary Wiens, Yan Yang - Connecting Star Formation in the Milky Way and Nearby Galaxies -II. An Observationally Driven Analytical Model for Predicting Cloud-Scale Star Formation Rates - https://arxiv.org/abs/2511.22985 - arXiv:2511.22985v2 Announce Type: replace -Abstract: We construct a model by integrating observational constraints from the Milky Way and nearby galaxies to predict cloud-scale star formation rates (SFRs). In the model, we first estimate the initial total mass of clumps in a cloud based on the cloud mass, and then generate the initial clump population of the cloud using the initial clump mass function. Next, we model the star formation histories (SFHs) of the cloud to assign an age to each clump. We then sort out the intermediate-age clumps and calculate the total embedded cluster mass. Finally, we predict the SFR based on the duration of the embedded phase. The model-predicted SFR is broadly consistent with the observed SFR, supporting the plausibility of the model. The model primarily provides a theoretical framework that integrates a wide range of observational results, thereby clarifying the tasks for future observations. - oai:arXiv.org:2511.22985v2 - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + AGN spectral variability across activity states and searches for axion-like particles + https://arxiv.org/abs/2509.22344 + arXiv:2509.22344v2 Announce Type: replace +Abstract: Axion-like particles (ALPs) are compelling candidates for dark matter and potential portals to new physics beyond the Standard Model. Photons traversing magnetized regions can convert into ALPs, producing characteristic, energy-dependent absorption features in astrophysical spectra. The probability of such conversions depends sensitively on both the photon energy and the properties of the intervening magnetic fields. + Most existing searches have focused on individual astrophysical sources, but uncertainties in the structure and strength of cosmic magnetic fields have limited their reach. Recently, we have demonstrated that active galactic nuclei (AGNs) observed through galaxy clusters provide especially promising targets for ALP searches. By stacking multiple AGN-cluster sightlines, one can average over poorly known magnetic field configurations in galaxy clusters and recover a distinctive ALP-induced spectral suppression, thereby significantly enhancing sensitivity. + In this work, we investigate a possible systematic uncertainty in such analyses: the intrinsic time-variability of AGN spectra. We demonstrate that AGN flux variability is correlated with spectral hardness, and that time-averaging over flaring and quiescent states can potentially mimic the suppression features imprinted by ALP-photon mixing. Our findings imply that the recent constraints remain conservative, and that incorporating detailed spectral variability into stacking analyses can further sharpen the search for axion-like particles. + oai:arXiv.org:2509.22344v2 + astro-ph.HE + astro-ph.CO + hep-ph + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - J. W. Zhou, Sami Dib, Pavel Kroupa + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Denys Malyshev, Lidiia Zadorozhna, Yuriy Bidasyuk, Andrea Santangelo, Oleg Ruchayskiy - The Kinematic Properties of T\.ZO Candidate HV 11417 with Gaia DR3 - https://arxiv.org/abs/2511.23368 - arXiv:2511.23368v2 Announce Type: replace -Abstract: HV 11417 is a candidate Thorne-\.Zytkow Object, a red supergiant with a neutron star core, located within the Small Magellanic Cloud (SMC). Previous studies have questioned, using Gaia DR2 data, whether HV 11417 was truly located at the distance of the SMC or was instead a foreground star. However, the proper motion measurement uncertainties for HV 11417 in DR2 were high. In this work, we use Gaia DR3 data to show that HV 11417 is very likely to be a true member of the SMC. We further analyze the kinematics of HV 11417 relative to its local environment, and compare it to populations of massive and evolved stars in the SMC. We find HV 11417 has a local transverse velocity of $52\pm15$ km/s, and thus qualifies as a runaway star (v$_\mathrm{loc}\geq$ 30 km/s). This runaway classification does not conclusively prove its nature as a T\.ZO, particularly given results from recent T\.ZO models, but does indicate that HV 11417 experienced a kinematic disruption in its evolution. - oai:arXiv.org:2511.23368v2 + Light Travel Time Effects in Kilonova Models + https://arxiv.org/abs/2510.09261 + arXiv:2510.09261v2 Announce Type: replace +Abstract: The extremely rapid evolution of kilonovae results in spectra that change on an hourly basis. These spectra are key to understanding the processes occurring within the event, but this rapid evolution is an unfamiliar domain compared to other explosive transient events, such as supernovae. In particular, the most obvious P Cygni feature in the spectra of AT2017gfo -- commonly attributed to strontium -- possesses an emission component that emerges after, and ultimately outlives, its associated absorption dip. This delay is theorised to arise from reverberation effects, wherein photons emitted earlier in the kilonova's evolution are scattered before reaching the observer, causing them to be detected at later times. We aim to examine how the finite speed of light -- and therefore the light travel time to an observer -- contributes to the shape and evolution of spectral features in kilonovae. Using a simple model, and tracking the length of the journey photons undertake to an observer, we are able to test the necessity of accounting for this time delay effect when modelling kilonovae. In periods where the photospheric temperature is rapidly evolving, we show spectra synthesised using a time independent approach are visually distinct from those where these time delay effects are accounted for. Therefore, in rapidly evolving events such as kilonovae, time dependence must be taken into account. + oai:arXiv.org:2510.09261v2 + astro-ph.HE astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Anna J. G. O'Grady + F. McNeill, S. A. Sim, C. E. Collins, L. J. Shingles, R. Damgaard, A. Sneppen, J. H. Gillanders - The art of simulating the early Universe. Part II. Non-canonical cases & gravitational waves - https://arxiv.org/abs/2512.15627 - arXiv:2512.15627v2 Announce Type: replace -Abstract: We present a discussion on lattice techniques for the simulation of non-canonical field theory circumstances, complementing our previous monograph (arXiv:2006.15122) on canonical cases. We begin by reviewing basic aspects of lattice field theory, including symplectic and non-symplectic evolution algorithms. We then introduce lattice implementations of non-canonical interactions, considering scalars with a non-minimal coupling to gravity, $\phi^2R$, non-minimal scalar kinetic theories, $\mathcal{G}_{ab}(\lbrace\phi_c\rbrace)\partial_\mu\phi^a\partial^\mu\phi^b$, and axion-like particle (ALP) interactions with Abelian gauge fields, $\phi F_{\mu\nu}\tilde F^{\mu\nu}$. Next, we discuss methods to set up special field configurations, including the creation of cosmic defect networks towards scaling (e.g. cosmic strings and domain walls), field configurations based on arbitrary power spectra or spatial profiles, and probabilistic methods as required e.g. for thermal configurations. We further extend the notion of non-canonical theories, discussing the discretization of scalar field dynamics in $d + 1$ dimensions, with $d \neq 3$. Unrelated to non-canonical aspects, we also discuss implementation(s) of gravitational wave (GW) dynamics on the lattice. This document represents the theoretical basis for the non-canonical field theory aspects (interactions, initial conditions, dimensionality) and GW dynamics implemented in ${\mathcal C}$osmo${\mathcal L}$attice v2.0, to be released in 2026. - oai:arXiv.org:2512.15627v2 + The choice of Planck CMB likelihood in cosmological analyses + https://arxiv.org/abs/2510.09430 + arXiv:2510.09430v2 Announce Type: replace +Abstract: We compare cosmological parameters from different Planck sky maps and likelihood pipelines, assessing robustness of cosmological results with respect to the choice of the latest Planck maps-likelihood combination. We show that, for the Planck multipole range retained in combination with ground-based observations, different products give very similar cosmological solutions; small remaining differences are reduced by the addition of other CMB datasets to Planck. In particular, constraints on extended cosmological models benefit from the addition of small-scale power from ground-based experiments and are completely insensitive to the choice of Planck maps and likelihood. For this work we derive and release a nuisance-marginalized dataset and CamSpec-NPIPE-lite likelihood for the Planck NPIPE data injected into the CamSpec likelihood - which are usually used to obtain the reference Planck PR4 cosmology. Using the extracted CMB spectra we show that the additional constraining power for cosmology is coming from polarization at all scales and from temperature at multipoles above 1500 when going from PR3 to PR4. We also show that full marginalization over the CamSpec foreground nuisance parameters can impact parameter inference and model selections when truncating some scales; our new likelihood enables correct combinations with other CMB datasets. + oai:arXiv.org:2510.09430v2 astro-ph.CO - gr-qc - hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jorge Baeza-Ballesteros, Daniel G. Figueroa, Adrien Florio, Joanes Lizarraga, Nicol\'as Loayza, Kenneth Marschall, Toby Opferkuch, Ben A. Stefanek, Francisco Torrent\'i, Ander Urio + http://creativecommons.org/licenses/by/4.0/ + Hidde Jense, Marc Vi\~na, Erminia Calabrese, J. Colin Hill - An Improved Machine Learning Approach for Radio Frequency Interference Mitigation in FAST-SETI Survey Archival Data - https://arxiv.org/abs/2512.15809 - arXiv:2512.15809v2 Announce Type: replace -Abstract: The search for extraterrestrial intelligence (SETI) commensal surveys aim to scan the sky to detect technosignatures from extraterrestrial life. A major challenge in SETI is the effective mitigation of radio frequency interference (RFI), a critical step that is particularly vital for the highly sensitive Five-hundred-meter Aperture Spherical radio Telescope (FAST). While initial RFI mitigation (e.g., removal of persistent and drifting narrowband RFI) are essential, residual RFI often persists, posing significant challenges due to its complex and various nature. In this paper, we propose and apply an improved machine learning approach, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, to identify and mitigate residual RFI in FAST-SETI commensal survey archival data from July 2019. After initial RFI mitigation, we successfully identify and remove 36977 residual RFIs (accounting for $\sim$ 77.87\%) within approximately 1.678 seconds using the DBSCAN algorithm. This result shows that we have achieved a 7.44\% higher removal rate than previous machine learning methods, along with a 24.85\% reduction in execution time. We finally find interesting candidate signals consistent with previous studies, and retain one candidate signal following further analysis. Therefore, DBSCAN algorithm can mitigate more residual RFI with higher computational efficiency while preserving the candidate signals that we are interested in. - oai:arXiv.org:2512.15809v2 - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Gamma-ray Orbital Modulation in Spider Pulsars: Three Discoveries and a Universal Modulated Fraction + https://arxiv.org/abs/2510.11699 + arXiv:2510.11699v2 Announce Type: replace +Abstract: Compact binary millisecond pulsars (also known as spiders) allow us to probe pulsar winds in their innermost regions, between the light cylinder (radius $\sim10^{7}$ cm) and the companion star (at $\sim10^{11}$ cm). Their flux is known to vary along the orbit, from radio to X-rays. During the past decade, gamma-ray orbital modulation (GOM) has been discovered in a handful of spiders, but its origin remains largely unknown. We present the results of a systematic search for GOM among 43 systems, selecting pulsed 0.1-1 GeV photons and using spin and orbital ephemeris from Fermi's Third Pulsar Catalog. We discover GOM from three spiders - PSR J1124-3653, PSR J1946-5403 and PSR J2215+5135 - and confirm four previous detections. In all seven cases so far, the GOM peaks near the pulsar's superior conjunction. The X-ray orbital light curves are usually in antiphase, peaking when the pulsar is at inferior conjunction, but we find one case where both gamma-rays and X-rays peak around superior conjunction: PSR J1946-5403. We measure the modulated fractions of the GOM and find consistent values for all seven spiders, with an average $22.0\pm2.6\%$. Including eclipsing systems seen edge-on, we find no clear dependence of the modulated fraction on the orbital inclination (within $\simeq$45-90$^\circ$). Our results challenge previous models proposed to explain GOM in spiders, based on inverse Compton and synchrotron emission close to the companion, since these predict a clear dependence on orbital inclination (stronger modulation at high inclinations). We nearly double the number of GOM detections in spiders, showing that it is more common than previously thought. + oai:arXiv.org:2510.11699v2 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3847/1538-3881/ae28ca - Li-Li Zhao, Xiao-Hang Luan, Xin Chao, Yu-Chen Wang, Jian-Kang Li, Zhen-Zhao Tao, Tong-Jie Zhang, Hong-Feng Wang, Dan Werthimer + 10.3847/1538-4357/ae2ff4 + Maksat Satybaldiev, Manuel Linares, Vittoria Vecchiotti - Machine-learning approaches to dispersion measure estimation for fast radio bursts - https://arxiv.org/abs/2512.24003 - arXiv:2512.24003v2 Announce Type: replace -Abstract: Fast radio bursts (FRBs) are bright, mostly millisecond-duration transients of extragalactic origin whose emission mechanisms remain unknown. As FRB signals propagate through ionized media, they experience frequency-dependent delays quantified by the dispersion measure (DM), a key parameter for inferring source distances and local plasma conditions. Accurate DM estimation is therefore essential for characterizing FRB sources and testing physical models, yet current dedispersion methods can be computationally intensive and prone to human bias. In this proof-of-concept study, we develop and benchmark three deep-learning architectures, a conventional convolutional neural network (CNN), a fine-tuned ResNet-50, and a hybrid CNN-LSTM model, for automated DM estimation. All models are trained and validated on a large set of synthetic FRB dynamic spectra generated using CHIME/FRB-like specifications. The hybrid CNN-LSTM achieves the highest accuracy and stability while maintaining low computational cost across the investigated DM range. Although trained on simulated data, these models can be fine-tuned on real CHIME/FRB observations and extended to future facilities, offering a scalable pathway toward real-time, data-driven DM estimation in large FRB surveys. - oai:arXiv.org:2512.24003v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + On the Short Dissipation Scales and Current-Sheet Properties of Low-Coronal EUV Brightenings + https://arxiv.org/abs/2510.22822 + arXiv:2510.22822v3 Announce Type: replace +Abstract: Solar Orbiter EUV observations reveal ubiquitous small-scale brightenings in the quiet-Sun low corona. We analyze the spatial and temporal dissipation scales of these events with a focus on the formation, evolution, and dissipation of associated current sheets. The brightenings are observed at heights of 1-5 Mm and span energies of 10^20 - 10^24 erg, well below the classical nanoflare regime, with the lowest-energy brightenings preferentially originating in the lowest coronal layers. Two distinct dissipation regimes are identified: impulsive brightenings with timescales of 1-10 s, consistent with fast, Alfvenic magnetic reconnection in low-beta plasma, and longer-lived heating episodes lasting 10-100 s, indicative of slower, resistive current-sheet dissipation under higher-beta conditions. The observed dissipation scales suggest a transition from kinetic-scale reconnection to macroscopic current-sheet heating in the low corona. These results support a multi-scale energy-release framework and highlight the role of low-altitude, small-scale current-sheet dissipation in quiet-Sun coronal heating. + oai:arXiv.org:2510.22822v3 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Hosein Rajabi, Zhejian Liu, Fereshteh Rajabi, Martin Houde + Olena Podladchikova - A spectroscopically confirmed, strongly lensed, metal-poor Type II supernova at z = 5.13 - https://arxiv.org/abs/2601.04156 - arXiv:2601.04156v2 Announce Type: replace -Abstract: Observing supernovae (SNe) in the early Universe (z > 3) provides a window into how both galaxies and individual stars have evolved over cosmic time, yet a detailed study of high-redshift stars and SNe has remained difficult due to their extreme distances and cosmological redshifting. To overcome the former, searches for gravitationally lensed sources allow for the discovery of magnified SNe that appear as multiple images - further providing the opportunity for efficient follow-up. Here we present the discovery of "SN Eos": a strongly lensed, multiply-imaged, SN II at a spectroscopic redshift of z = 5.133 +/- 0.001. SN Eos exploded in a Lyman-{\alpha} emitting galaxy when the Universe was only ~1 billion years old, shortly after it reionized and became transparent to ultraviolet radiation. A year prior to our discovery in JWST data, archival HST imaging of SN Eos reveals rest-frame far ultraviolet (~1,300{\AA}) emission, indicative of shock breakout or interaction with circumstellar material in the first few (rest-frame) days after explosion. The JWST spectroscopy of SN Eos, now the farthest spectroscopically confirmed SN ever discovered, shows that SN Eos's progenitor star likely formed in a metal-poor environment (<= 0.1 Z_{\odot}), providing the first direct evidence of massive star formation in the metal-poor, early Universe. SN Eos would not have been detectable without the extreme lensing magnification of the system, highlighting the potential of such discoveries to eventually place constraints on the faint end of the cosmic star-formation rate density in the very early Universe. - oai:arXiv.org:2601.04156v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + NEOForCE: Near-Earth Objects' Forecast of Collisional Events + https://arxiv.org/abs/2510.25923 + arXiv:2510.25923v2 Announce Type: replace +Abstract: Robust impact monitoring of near-Earth objects is an essential task of planetary defense. Current systems such as NASA's Sentry-II, the University of Pisa's CLOMON2, and ESA's Aegis have been highly successful, but independent approaches are essential to ensure reliability and to cross-validate predictions of possible impacts. We present NEOForCE (Near-Earth Objects' Forecast of Collisional Events), a new independent monitoring system for asteroid impact prediction. By relying on orbital solutions from DynAstVO at Paris Observatory and using an original methodology for uncertainty propagation, NEOForCE provides an alternative line of verification for impact assessments and strengthens the overall robustness of planetary defense. As other monitoring systems, NEOForCE samples several thousand virtual asteroids from the uncertainty region and integrates their orbits up to 100 years into the future. Instead of searching for close approaches of the virtual asteroids with the Earth, our system looks for times when the Earth comes close to the realistic uncertainty regions around them, which are mostly stretched along their osculating orbits. We also estimate the maximal impact probability, and only if this value is large enough do we continue to the next step. In this second step, we compute how the original asteroid orbit should be modified so that the new trajectory leads to an Earth impact, which allows us to confirm the possible collision and estimate the impact probability. We tested NEOForCE against NASA's Sentry-II system on five representative asteroids: 2000 SG344, 2005 QK76, 2008 JL3, 2023 DO and 2008 EX5. NEOForCE successfully recovered mostly all possible collisions reported by Sentry-II with impact probabilities above e-7, demonstrating the robustness of our approach. In addition, NEOForCE identified several potential impacts at the e-7 - e-6 level that Sentry-II did not report. + oai:arXiv.org:2510.25923v2 + astro-ph.EP + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - David A. Coulter, Conor Larison, Justin D. R. Pierel, Seiji Fujimoto, Vasily Kokorev, Joseph F. V. Allingham, Takashi J. Moriya, Matthew Siebert, Yoshihisa Asada, Rachel Bezanson, Maru\v{s}a Brada\v{c}, Gabriel Brammer, John Chisholm, Dan Coe, Pratika Dayal, Michael Engesser, Steven L. Finkelstein, Ori D. Fox, Lukas J. Furtak, Anton M. Koekemoer, Thomas Moore, Minami Nakane, Masami Ouchi, Richard Pan, Robert Quimby, Armin Rest, Johan Richard, Luke Robbins, Louis-Gregory Strolger, Fengwu Sun, Tommaso Treu, Hiroto Yanagisawa, Abdurro'uf, Aadya Agrawal, Ricardo Amor\'in, Joseph P. Anderson, Rodrigo Angulo, Hakim Atek, Franz E. Bauer, Larry D. Bradley, Volker Bromm, Mateusz Bronikowski, Christopher J. Conselice, Christa DeCoursey, James M. DerKacy, Guillaume Desprez, Suhail Dhawan, Jose M. Diego, Eiichi Egami, Andreas Faisst, Brenda Frye, Sebastian Gomez, Mauro Gonz\'alez-Otero, Massimo Griggio, Yuichi Harikane, Kohei Inayoshi, Saurabh W. Jha, Yolanda Jim\'enez-Teja, Jeyhan S. Kartaltepe, Patrick L. Kelly, Lindsey A. Kwok, Zachary G. Lane, Xiaolong Li, Ivo Lobbe, Paulo A. A. Lopes, Ray A. Lucas, Georgios E. Magdis, Nicholas S. Martis, Jorryt Matthee, Ashish K. Meena, Rohan P. Naidu, Ga\"el Noirot, Masamune Oguri, Estefania Padilla Gonzalez, Massimo Pascale, Tanja Petrushevska, Massimo Ricotti, Daniel Schaerer, Stefan Schuldt, Melissa Shahbandeh, William Sheu, Koji Shukawa, Akiyoshi Tsujita, Eros Vanzella, Qinan Wang, John Weaver, Robert Williams, Rogier Windhorst, Yi Xu, Yossef Zenati, Adi Zitrin + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Dmitrii E. Vavilov, Daniel Hestroffer - Nitrogen enhancement of GN-z11 by metal pollution from supermassive stars - https://arxiv.org/abs/2601.04344 - arXiv:2601.04344v2 Announce Type: replace -Abstract: Spectroscopic observations by the James Webb Space Telescope (JWST) have revealed young, compact, high-redshift ($z$) galaxies with high nitrogen-to-oxygen (N/O) ratios. GN-z11 at z=10.6 is one of these galaxies. One possible scenario for such a high N/O ratio is pollution from supermassive stars (SMSs), from which stellar winds are expected to be nitrogen-rich. The abundance pattern is determined by both galaxy evolution and SMS pollution, but so far, simple one-zone models have been used. Using a galaxy formation simulation, we tested the SMS scenario. We used a cosmological zoom-in simulation that includes chemical evolution driven by rotating massive stars (Wolf-Rayet stars), supernovae, and asymptotic giant branch stars. As a post-process, we assumed the formation of an SMS with a mass between $10^3$ and $10^5$ $M_\odot$ and investigated the contribution of its ejecta to the abundance pattern. The N/O ratio was enhanced by the SMS ejecta, and the abundance pattern of GN-z11, including carbon-to-oxygen and oxygen-to-hydrogen ratios, was reproduced by our SMS pollution model if the pollution mass fraction ranges within 10-30 per cent. Such a pollution fraction can be realized when the gas ionized by the SMS is polluted, and the gas density is $10^4$-$10^5$ cm$^{-3}$ assuming a Str\"omgren sphere. We also compared the abundance pattern with those of other N/O-enhanced high-$z$ galaxies. Some of these galaxies can also be explained by SMS pollution. - oai:arXiv.org:2601.04344v2 + Bars in low-density environments rotate faster than bars in dense regions + https://arxiv.org/abs/2511.02054 + arXiv:2511.02054v2 Announce Type: replace +Abstract: Does the environment of a galaxy directly influence the kinematics of its bar? We present observational evidence that bars in high-density environments exhibit significantly slower rotation rates than bars in low-density environments. Galactic bars are central, extended structures composed of stars, dust and gas, present in approximately 30 to 70 per cent of luminous spiral galaxies in the local Universe. Recent simulation studies have suggested that the environment can influence the bar rotation rate, $R$, which is used to classify bars as either fast ($1\leq R \leq1.4$) or slow ($R \gt 1.4$). We use estimates of $R$ obtained with the Tremaine-Weinberg method applied to Integral Field Unit spectroscopy from MaNGA and CALIFA. After cross-matching these with the projected neighbour density, $\log\Sigma$, we retain 286 galaxies. The analysis reveals that bars in high-density environments are significantly slower (median $R = 1.65^{+0.13}_{-0.11}$) compared to bars in low-density environments (median $R = 1.39^{+0.09}_{-0.08}$); Anderson-Darling $\textit{p}$-value of $p_{\mathrm{AD}}= 0.002$ ($3.1\,\sigma$). This study marks the first empirical test of the hypothesis that fast bars are formed by global instabilities in isolated galaxies, while slow bars are triggered by tidal interactions in dense environments, in agreement with predictions from numerous $\textit{N}$-body simulations. Future studies would benefit from a larger sample of galaxies with reliable Integral Field Unit data, required to measure bar rotation rates. Specifically, more data are necessary to study the environmental influence on bar formation within dense settings (i.e. groups, clusters and filaments). + oai:arXiv.org:2511.02054v2 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Sho Ebihara, Michiko S. Fujii, Takayuki R. Saitoh, Yutaka Hirai, Hideyuki Umeda, Yuki Isobe, Chris Nagele + Natalia Puczek (Oxford Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Oxford, UK), Tobias G\'eron (Oxford Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Oxford, UK, Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Canada), Rebecca J. Smethurst (Oxford Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Oxford, UK), Chris J. Lintott (Oxford Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Oxford, UK) - Triaxial Magnetars as Sources of Fast Radio Bursts - https://arxiv.org/abs/2601.04953 - arXiv:2601.04953v2 Announce Type: replace -Abstract: I suggest that some of the mysterious temporal properties of Fast Radio Bursts (FRB) may be explained if they are produced by dynamically triaxial magnetars. If the bursts are narrowly collimated along open field lines, then observed repeating FRB may be those in which the moment of inertia tensor is only slightly triaxial and the rotation axis, open field lines and radiation point nearly to the observer. Apparently non-repeating FRB may be triaxial with the direction of open field lines and radiation wandering across the sky, reducing their duty factors by several orders of magnitude. A slightly triaxial moment tensor in repeaters moves the line of sight into or out of the radiation pattern or within it, explaining periods of greater or lesser (or absent) activity, and making the probability of detecting a burst and hence the burst rate vary aperiodically. The dynamics of triaxial bodies might thwart the coherent integration of gravitational signals from rotating accreting neutron stars. - oai:arXiv.org:2601.04953v2 + Diagnosing Interstellar Magnetic Turbulence with TeV Pulsar Halos + https://arxiv.org/abs/2512.07290 + arXiv:2512.07290v2 Announce Type: replace +Abstract: Interstellar magnetic field is essential in various astrophysical phenomena and processes. Pulsar halos are a recently discovered class of TeV gamma-ray sources formed by escaping electrons/positrons from pulsars. The morphology of the halo is regulated by the diffusion of those escaping particles, and hence carries information of the interstellar magnetic field. We suggest that the morphology of TeV pulsar halos can be used as a novel probe of the properties of interstellar magnetic field around the pulsar, such as the Alfv\'{e}nic Mach number and the mean direction. We establish a theoretical relation between these quantities and the observational features of the halo's morphology based on the anisotropic diffusion model, and show how X-ray observations of the pulsar halos can further improve the diagnosis of the magnetic field. + oai:arXiv.org:2512.07290v2 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - J. I. Katz + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/vt3s-rbj1 + Phys. Rev. D 113, L021303 (2026) + Chao-Ming Li, Ruo-Yu Liu, Huirong Yan - Constraining the Primordial Black Hole Abundance with Space-Based Detectors - https://arxiv.org/abs/2601.05069 - arXiv:2601.05069v2 Announce Type: replace -Abstract: Overdense regions can collapse into primordial black holes (PBHs) in the early universe, which are a compelling candidate for dark matter. Current constraints leave the asteroid-mass window the only possible one for PBH to account for all the dark matter, which can only be probed indirectly by the scalar-induced gravitational waves (GWs) sourced by the curvature perturbation which forms PBH. In this work, we explore the capabilities of future space-based gravitational wave detectors, including LISA, Taiji, and TianQin, to constrain such induced GWs as well as the PBH abundance. We systematically account for the width of the primordial curvature power spectrum, and find that the asteroid-mass window can be fully probed by all three space-based interferometers. If PBHs constitute the majority of dark matter, the induced GW leaves a strong signal in the mHz band with a signal-to-noise ratio of $10^3$--$10^4$. - oai:arXiv.org:2601.05069v2 + Hidden pattern of self-invariant cosmic expansion: Empirical evidence from Hubble diagram of supernovae + https://arxiv.org/abs/2601.05512 + arXiv:2601.05512v3 Announce Type: replace +Abstract: We present empirical evidence extracted directly from the Pantheon Catalog of SNeIa demonstrating that the speed of light varies as the universe expands. Moreover, the speed of light must vary in a specific quantifiable manner. To show this, we reformulate the kinematics of late-time acceleration using Dolgov's power-law cosmology $a=(t/t_0)^\mu$ [Phys. Rev. D 55, 5881 (1997)] and Barrow's varying speed of light $c=c_0a^{-\zeta}$ [Phys. Rev. D 59, 043515 (1999)]. In this cosmology, light traveling through an expanding universe undergoes an additional refraction caused by the varying c along its path, resulting in a modified Lemaitre redshift formula $1+z=a^{-(1+\zeta)}$. The new model achieves a high-quality fit to the Pantheon Catalog of SNeIa and exhibits a strong degeneracy along the locus $(1+\zeta)\,\mu=1$. This empirical relation indicates a self-invariant cosmic evolution: at all instants during the late-time epoch, the speed of light is exactly proportional to the rate of cosmic expansion, viz. $c=\mu^{-1}c_0t_0\,da/dt$, a characteristic that is absent in the $\Lambda$CDM model. This synchronous behavior between $c$ and $da/dt$ carries profound cosmological implications that we will discuss, regarding (i) the nature of late-time acceleration; (ii) a resolution to the horizon problem; (iii) Kolb's coasting universe model [Astrophys. J. 344, 543 (1989)]; (iv) a generalized cosmological principle into the time domain; and (v) a novel conformally flat metric applicable to cosmology. This newfound kinematic $c\propto da/dt$ relation represents a stringent requirement that any viable dynamical model of cosmology must satisfy, a requirement that the $\Lambda$CDM model does not fulfill. Thus, our paper delivers the clearest and most decisive evidence to date that challenges the standard $\Lambda$CDM paradigm of cosmology and calls for variable-$c$ modifications to General Relativity. + oai:arXiv.org:2601.05512v3 astro-ph.CO gr-qc - hep-ph - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Wencong Hong, Shi Pi, Ao Wang, Zhenyu Zhang + Hoang Ky Nguyen - An eclipsing 8.56 minute orbital period mass-transferring binary - https://arxiv.org/abs/2601.07925 - arXiv:2601.07925v3 Announce Type: replace -Abstract: We report the discovery of ATLAS J101342.5-451656.8 (hereafter ATLAS J1013-4516), an 8.56 minute orbital period mass transferring AM Canum Venaticorum binary with mean Gaia magnitude G=19.51. The system was identified via periodic variability in Asteroid Terrestrial-impact Last Alert System light curves of Gaia white dwarf candidates. Follow-up spectroscopy with the Large Lenslet Array Magellan Spectrograph reveals a helium dominated accretion disk, while high speed ULTRACAM photometry shows pronounced primary and secondary eclipses. We construct a decade long orbital timing baseline using ATLAS and Gaia survey photometry together with high speed observations from ULTRACAM on the NTT and proto Lightspeed on the Magellan Clay telescope. From this baseline we measure an orbital period derivative Pdot = -1.60 +/- 0.07 x 10^-12 seconds per second. Interpreted in the context of stable mass transfer, the magnitude and sign of Pdot indicate orbital evolution governed by the interplay between gravitational wave driven angular momentum losses and mass transfer, directly probing the donor star structural response to mass loss. Assuming angular momentum loss dominated by gravitational radiation, we constrain the component masses and infer the characteristic gravitational wave strain. We predict a four year Laser Interferometer Space Antenna signal to noise ratio greater than 10, establishing ATLAS J1013-4516 as a strong prospective space based gravitational wave source that probes long term orbital evolution in the mass transferring regime. - oai:arXiv.org:2601.07925v3 - astro-ph.SR - Wed, 21 Jan 2026 00:00:00 -0500 + Digging into the Interior of Hot Cores with ALMA. VI. The Formation of Low-mass Multiple Systems in High-mass Cluster-forming Regions + https://arxiv.org/abs/2601.08904 + arXiv:2601.08904v2 Announce Type: replace +Abstract: Most stars form in multiple systems, with profound implications in numerous astronomical phenomena intrinsically linked to multiplicity. However, our knowledge about the process on how multiple stellar systems form is incomplete and biased toward nearby molecular clouds forming only low-mass stars, which are unrepresentative of the stellar population in the Galaxy. Most stars form within dense cores in clusters alongside high-mass stars (>8 M$_{\odot}$), as likely the Sun did. Here we report deep ALMA 1.33 mm dust continuum observations at ~160 au spatial resolution, revealing 72 low-mass multiple systems embedded in 23 high-mass cluster-forming regions, as part of the Digging into the Interior of Hot Cores with ALMA (DIHCA) survey. We find that the companion separation distribution presents a distinct peak at ~1200 au, in contrast to the one at ~4000 au observed in nearby low-mass regions. The shorter fragmentation scale can be explained by considering the higher pressure exerted by the surrounding medium, which is higher than the one in low-mass regions, due to the larger turbulence and densities involved. Because the peak of the companion separation distribution occurs at much larger scales than the expected disk sizes, we argue that the observed fragmentation is produced by turbulent core fragmentation. Contrary as predicted, the multiplicity fraction remains constant as the stellar density increases. We propose that in the extremely dense environments where high-mass stars form, dynamical interactions play an important role in disrupting weakly bound systems. + oai:arXiv.org:2601.08904v2 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Emma T. Chickles (Massachusetts Institute of Technology, Cambridge, USA), Joheen Chakraborty (Massachusetts Institute of Technology, Cambridge, USA), Kevin B. Burdge (Massachusetts Institute of Technology, Cambridge, USA), Vik S. Dhillon (University of Sheffield, Sheffield, UK, Instituto de Astrofisica de Canarias, La Laguna, Spain), Paul Draghis (Massachusetts Institute of Technology, Cambridge, USA), Kareem El-Badry (California Institute of Technology, Pasadena, USA), Matthew J. Green (Max Planck Institute for Astronomy, Heidelberg, Germany), Aaron Householder (Massachusetts Institute of Technology, Cambridge, USA), Sarah Hughes (Massachusetts Institute of Technology, Cambridge, USA), Christopher Layden (Massachusetts Institute of Technology, Cambridge, USA), Stuart P. Littlefair (University of Sheffield, Sheffield, UK), James Munday (University of Warwick, Coventry, UK), Ingrid Pelisoli (University of Warwick, Coventry, UK), Maya S. Redden (Stanford University, Stanford, USA), John Tonry (University of Hawaii, Honolulu, USA), Jan van Roestel (Institute of Science and Technology Austria, Klosterneuburg, Austria, University of Amsterdam, Amsterdam, The Netherlands), F. Elio Angile (Massachusetts Institute of Technology, Cambridge, USA), Alex J. Brown (University of Hamburg, Hamburg, Germany), Noel Castro (University of Warwick, Coventry, UK), Jack Dinsmore (Stanford University, Stanford, USA), Martin Dyer (University of Sheffield, Sheffield, UK, Research Software Engineering, University of Sheffield, Sheffield, UK), Gabor Furesz (Massachusetts Institute of Technology, Cambridge, USA), Michelle Gabutti (Massachusetts Institute of Technology, Cambridge, USA), James Garbutt (University of Sheffield, Sheffield, UK), Daniel Jarvis (University of Sheffield, Sheffield, UK), Mark R. Kennedy (University College Cork, Cork, Ireland), Paul Kerry (University of Sheffield, Sheffield, UK), James McCormac (University of Warwick, Coventry, UK), Geoffrey Mo (California Institute of Technology, Pasadena, USA, Carnegie Observatories, Pasadena, USA), Dave Osip (Las Campanas Observatory, La Serena, Chile), Steven Parsons (University of Sheffield, Sheffield, UK), Eleanor Pike (University of Sheffield, Sheffield, UK), Jack Piotrowski (Carnegie Observatories, Pasadena, USA), Roger W. Romani (Stanford University, Stanford, USA), David Sahman (University of Sheffield, Sheffield, UK), Rob Simcoe (Massachusetts Institute of Technology, Cambridge, USA) + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Qiuyi Luo, Patricio Sanhueza, Stella S. R. Offner, Fernando Olguin, Adam Ginsburg, Fumitaka Nakamura, Kaho Morii, Yu Cheng, Kei Tanaka, Junhao Liu, Tie Liu, Xing Lu, Qizhou Zhang, Kotomi Taniguchi, Piyali Saha, Shanghuo Li, Xiaofeng Mai - The drastic impact of Eddington-limit induced mass ejections on massive star populations - https://arxiv.org/abs/2601.08822 - arXiv:2601.08822v2 Announce Type: replace -Abstract: Massive stars are the key engines of the Universe. However, their evolution and thus their ionizing feedback are still not fully understood. One of the largest gaps in current stellar evolution calculations is the lack of a model for the mass ejections that occur when the stars reach the Eddington limit, such as during an Luminous Blue Variable (LBV) phase. We aim to remedy this situation by providing a physically motivated and empirically calibrated method applicable in any 1D stellar evolution code to approximate the effect of such mass loss on stellar evolution. We employ the 1D stellar evolution code MESA, in which we implement a new mass-loss prescription that is acting when stellar models inflate too much when reaching the Eddington limit. Synthetic massive-star stellar populations using calculated grids of single-star models with this mass loss prescription are compared with the observed populations in the Large and Small Magellanic Clouds. In combination with already computed grids of binary evolution models, we investigate the impact of binarity on our predictions. Our single-star models reproduce key features of the observed stellar populations, namely (i) the absence of stars located beyond the Humphreys-Davidson limit, (ii) an upper limit of RSG luminosities, (iii) the faintest observed single WR stars, (iv) the absolute number of O-stars, WRs, and RSGs, (v) WO stars in low metallicity environments, and (vi) the positions of LBV stars in the HRD. Our binary population explains at the same time the 70% binary fraction of O-stars and the 40% binary fraction of WR stars. However, our synthetic population also has caveats, such as an overproduction of bright H-free WN stars. Our results show that the effect of Eddington-limit induced mass ejections on the structure and evolution of massive stars can remove tension between predicted and observed massive star populations. - oai:arXiv.org:2601.08822v2 - astro-ph.SR + Resonant Scattering of the He I 1.0833$\mu$m Triplet in H II Regions: Emission Spectra + https://arxiv.org/abs/2601.11710 + arXiv:2601.11710v2 Announce Type: replace +Abstract: Resonant scattering of He I 1.0833$\mu$m triplet photons by metastable He 2 $^3$S$_1$ is studied for optical depths characteristic of H II regions. Regions with large He 2 $^3$S$_1$ column densities are predicted to have unusually broad, multi-peaked 1.0833$\mu$m emission profiles, with the centroid blue-shifted by up to $\sim$14 km/s relative to other lines. The feature FWHM can exceed 100 km/s for some regions. Resonant trapping enhances dust absorption and reduces the He I 1.0833$\mu$m emission. Care must be taken when using the He I 1.0833$\mu$m/H I 1.0941$\mu$m (Pa$\gamma$) ratio to estimate the He$^+$/H$^+$ ratio. Predicted spectra are computed for examples, including M-17B and NGC3603 in the Galaxy, and a star-forming region in M51. Observations of the 1.0833$\mu$m triplet with spectrometers such as NIRSPEC, CARMENES, or X-Shooter can confirm the predicted effects of resonant scattering in H II regions, and constrain the nebular conditions. + oai:arXiv.org:2601.11710v2 astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - D. Pauli, N. Langer, A. Schootemeijer, P. Marchant, H. Jin, A. Ercolino, A. Picco, R. Willcox, H. Sana + http://creativecommons.org/licenses/by-sa/4.0/ + B. T. Draine - Using 23 Years of ACS/SBC Data to Understand Backgrounds: Explaining & Predicting Background Variations - https://arxiv.org/abs/2601.09682 - arXiv:2601.09682v2 Announce Type: replace -Abstract: Recent analysis of 23 years of Hubble Space Telescope ACS/SBC data has shown that background levels can vary considerably between observations, with most filters showing over an order of magnitude variation. For the shorter-wavelength filters, the background is understood to be dominated by airglow; however, what precisely drives background variations is not well constrained for any filter. Here, we explore the causes of the background variation. Using over 8,000 archival SBC observations, we developed a machine learning model that can accurately predict the background for an observation, based upon a set of 23 observational parameters. This model indicates that, depending on filter, the SBC background is generally dominated by Solar elevation, Solar separation angle, Earth limb angle of observation, SBC temperature, and target Galactic latitude. - oai:arXiv.org:2601.09682v2 - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Updated Metallicity Diagnostics for Precision Oxygen Abundance Measurements in High-redshift Galaxies with JWST + https://arxiv.org/abs/2601.12413 + arXiv:2601.12413v3 Announce Type: replace +Abstract: Recent work has demonstrated that widely used strong-line oxygen abundance indicators, such as O3N2, $\rm R23$, and $\widehat{\rm R}$, suffer from large uncertainties when applied to high-redshift galaxies. We show that this loss of precision primarily arises because, at fixed \Oabund, galaxies span a wide dynamic range in ionization parameter and nitrogen enrichment. Here we develop updated indicators that explicitly incorporate both effects via the proxies O32 and N2O2. We define ${\rm R}_{\rm u}\equiv \rm R23+\alpha_1 O32+\alpha_2 N2O2$, $\widehat{\rm R}_{\rm u}\equiv \rm \widehat{R}+\beta_1 O32+\beta_2 N2O2$, and ${\rm O}_{\rm u}\equiv \rm O3N2+\gamma_1 O32+\gamma_2 N2O2$, and calibrate \Oabund~as low-order polynomials in each composite indicator. Applied to a JWST sample with $T_{\rm e}$-method abundances, the updated indicators substantially tighten the correlations with \Oabund, boosting adjusted coefficients of determination from $\mathbb{R}^2\lesssim 0$ (classical indicators) to $\mathbb{R}^2\gtrsim 0.5$ for the full sample and to $\sim 0.7$ at $z>2$. The residuals reveal a redshift evolution in the mapping between \Oabund, strong lines, ionization, and nitrogen enrichment, with a pivotal turning point near the cosmic noon ($z\sim 2$). Our calibrations provide a practical, physically grounded path to precise metallicity measurements in the JWST era and a firmer basis for quantifying early chemical enrichment and feedback. + oai:arXiv.org:2601.12413v3 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Christopher J. R. Clark, Roberto J. Avila, Alyssa Guzman, Norman A. Grogin + Shihong Liu, Yu Rong, Tie Li, Yao Yao, Cheng Jia, Enci Wang, Hongxin Zhang, Zhicheng He, Huiyuan Wang, Xu Kong - The impact of disc photoevaporation on the long-term evolution of giant planets in mean motion resonances - https://arxiv.org/abs/2601.10811 - arXiv:2601.10811v2 Announce Type: replace -Abstract: We investigate the long-term impact of disc photoevaporation on the dynamical stability and evolution of giant planet pairs in mean motion resonances. Using two-dimensional hydrodynamical simulations with FARGO3D, in which we have included mass-loss due to photoevaporation, we explore a parameter space covering disc mass, viscosity, planet mass, and resonance type. We find that strong photoevaporation depletes gas in the common gap between the planets, slowing migration and suppressing planet-disc interactions that typically lead to resonance breaking and eccentricity damping. This stabilising effect is most significant for 3:2 resonances, which are more prone to disruption due to the reduced planet spacing. In contrast, 2:1 resonances are generally more robust but can still be destabilised at high disc mass and moderate-to-strong photoevaporation due to asymmetric torques. Photoevaporation can therefore stabilise resonances that would otherwise break, or conversely disrupt resonances that are natively more stable. Even in cases where photoevaporation does not directly affect resonance stability, it typically results in increased planetary eccentricities. These results highlight the complex, system-dependent nature of resonance evolution, with implications for the final orbital architectures of giant planet systems and their detectability via astrometry from missions such as Gaia. - oai:arXiv.org:2601.10811v2 - astro-ph.EP - Wed, 21 Jan 2026 00:00:00 -0500 + Unveiling Hidden Clustering: An Unsupervised Machine Learning Study of Repeating FRB 20220912A + https://arxiv.org/abs/2601.14065 + arXiv:2601.14065v2 Announce Type: replace +Abstract: Fast Radio Bursts (FRBs) are millisecond-duration radio transients of extragalactic origin. Classifying repeating FRBs is essential for understanding their emission mechanisms, but remains challenging due to their short durations, high variability, and increasing data volume. Traditional methods often rely on subjective criteria and struggle with high-dimensional data. In this study, we apply an unsupervised machine learning framework that combines Uniform Manifold Approximation and Projection (UMAP) and Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) to eight observed parameters from FRB 20220912A. Our analysis reveals three distinct clusters of bursts with varying spectral and fluence properties. Comparisons with clustering studies on other repeaters show that some of our clusters share similar features with sources such as FRB 20201124A and FRB 121102, suggesting possible common emission mechanisms. We also provide qualitative interpretations for each cluster, highlighting the spectral diversity within a single source. Notably, one cluster shows broadband emission and high fluence, which are typically seen in non-repeating FRBs. This raises the possibility that some non-repeaters may be misclassified repeaters due to observational limitations. Our results demonstrate the utility of machine learning in uncovering intrinsic diversity in FRB emission and provide a foundation for future classification studies. + oai:arXiv.org:2601.14065v2 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Emmanuel J. Greenfield, James E. Owen + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + An-Chieh Hsu, Tetsuya Hashimoto, Tomotsugu Goto, Tomoki Wada, Bjorn Jasper Raquel - Radiative Cooling Effects on Plasmoid Formation in Black Hole Accretion Flows with Multiple Magnetic Loops - https://arxiv.org/abs/2601.10968 - arXiv:2601.10968v2 Announce Type: replace -Abstract: We investigate the influence of radiative cooling on plasmoid formation in black hole accretion flows using 2D and 3D two-temperature GRMHD simulations with multi-loop magnetic fields. Our results show that radiative cooling suppresses the transition to a MAD state by reducing magnetic flux accumulation near the horizon, modifies the disk structure via lower electron temperatures and increased equatorial density, and alters reconnection properties:compressing current sheets, shortening plasmoid lifetimes, and increasing their frequency. We also find enhanced negative energy-at-infinity density in plasmoids near the ergosphere. These findings indicate that radiative cooling critically shapes both large scale accretion dynamics and small-scale reconnection phenomena, potentially modulating black hole energy extraction through reconnection-driven Penrose processes. - oai:arXiv.org:2601.10968v2 - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + A Not-So-Compact Companion: Massive, Oversize White Dwarf in a Post-Common Envelope Eclipsing Binary + https://arxiv.org/abs/2601.14378 + arXiv:2601.14378v2 Announce Type: replace +Abstract: We provide a detailed characterization of 2M07515777+1807352, a post-common envelope eclipsing binary system with a 10.3 d, nearly, but not quite, circular orbit (e = 0.02). This system consists of a massive white dwarf (WD) ($1.08$ M$_{\odot}$) and a 4400 K main-sequence companion (0.66 M$_{\odot}$). This WD is among the most massive known within post-common envelope binary systems. We also find, through both spectral energy distribution and $\it{TESS}$ light curve analyses, that the WD has a radius of $1.54\pm 0.07 R_{\oplus}$, roughly $12\sigma$ larger than the expected value from WD mass-radius relationships. Both the Lomb-Scargle analysis and the $v \sin{i}$ of the system indicate the main-sequence companion to be super-synchronously rotating at a period of $\sim$6 days, which may suggest accretion occurred during the evolution of the system. This binary also shares similar physical characteristics with six other post-common envelope systems hosting massive WDs, which may point to a shared formation pathway. We model the history of this system with COSMIC and find that it likely formed through an episode of common envelope evolution following the onset of mass transfer when the progenitor primary was on either the early or the thermally pulsing stages of the asymptotic giant branch. As a result of its properties, the study of 2M07515777+1807352 can provide new insights regarding many key outstanding questions in our understanding of common envelope evolution. + oai:arXiv.org:2601.14378v2 + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Jing-Ze Xia, Hong-Xuan Jiang, Yosuke Mizuno, Antonios Nathanail, M. Christian Fromm + Erin M. Motherway, Evan Linck, Robert D. Mathieu, Don Dixon, Keivan G. Stassun, Katelyn Breivik, Steven R. Majewski, Onno Pols - KiDS-Legacy: WIMP dark matter constraints from the cross-correlation of weak lensing and Fermi-LAT gamma rays - https://arxiv.org/abs/2601.11223 - arXiv:2601.11223v2 Announce Type: replace -Abstract: Dark matter dominates the matter content of the Universe, and its properties can be constrained through large-scale structure probes such as the cross-correlation between the unresolved gamma-ray background (UGRB) and weak gravitational lensing. We analysed 15 years of Fermi-LAT data, constructing UGRB intensity maps in ten energy bins (0.5-1000 GeV), and cross-correlated them with KiDS-Legacy shear in six tomographic bins. The measurements were performed using angular power spectra estimated with the pseudo-$C_\ell$ method. No significant cross-correlation is found. Based on this non-detection, we present 95% upper bounds on the weakly interacting massive particle (WIMP) decay rate $\Gamma_{\rm dec}$ and velocity-averaged annihilation cross-section $\langle\sigma_{\rm ann} v\rangle$ as functions of mass. We compare our results with bounds from other cosmological tracers and from local probes, and found them to be complementary, particularly at low masses ($\rm GeV/TeV$). In addition, using a Euclid-like lensing survey cross-correlated with Fermi-LAT, we forecast $\sim$2 times tighter limits, highlighting the potential of forthcoming data to strengthen constraints on dark matter annihilation and decay. - oai:arXiv.org:2601.11223v2 - astro-ph.CO + The Supernova Remnant G284.3$-$1.8 and Its Relation to the Gamma-ray Binary 1FGL J1018.6$-$5856 + https://arxiv.org/abs/2601.14801 + arXiv:2601.14801v2 Announce Type: replace +Abstract: G284.3$-$1.8 is a supernova remnant with a radio shell and thermal X-ray emission. Located near its center is the gamma-ray binary 1FGL J1018.6$-$5856, although the physical association between the two systems is not clear yet. Our X-ray spectroscopy with Suzaku reveals that G284.3$-$1.8 and 1FGL J1018.6$-$5856 have compatible absorption column densities of $N_\mathrm{H} = 6\textrm{--}7 \times 10^{21}~\mathrm{cm}^{-2}$, indicating that the two systems have similar distances. The actual distance is determined as $3~\mathrm{kpc}$ using $\mathrm{^{12}CO}$ ($J=1\textrm{--}0$) data obtained with NANTEN. The X-ray spectrum of G284.3$-$1.8 shows a strong K-shell emission line of Mg, confirming that the earlier claim that the SNR is one of the few Mg-rich SNRs. Comparing recent stellar models taking into account the "shell merger" processes, we find that the obtained Mg-to-Ne mass ratio of $M_\mathrm{Mg}/M_\mathrm{Ne} = 0.73^{+0.07}_{-0.03}$ and Si-to-Mg mass ratio of $M_\mathrm{Si}/M_\mathrm{Mg} = 0.44\pm0.03$ suggest a supernova explosion that would have left a neutron star. The characteristics of 1FGL J1018.6$-$5856, on the other hand, are better explained with a model in which its compact object is neutron star. The present results, therefore, would suggest a possible scenario where G284.3$-$1.8 and 1FGL J1018.6$-$5856 are both remnants of a common supernova explosion although further observational tests are necessary. + oai:arXiv.org:2601.14801v2 astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Shiyang Zhang, Hendrik Hildebrandt, Ziang Yan, Tilman Tr\"oster, Athithya Aravinthan, Marika Asgari, Deaglan J. Bartlett, Maciej Bilicki, Dominik Els\"asser, Catherine Heymans, Benjamin Joachimi, Lauro Moscardini, Dennis Neumann, Anya Paopiamsap, Robert Reischke, Benjamin St\"olzner + Natsuki Terano, Takaaki Tanaka, Hiromasa Suzuki, Rei Enokiya, Hiroyuki Uchida, Kai Matsunaga, Takuto Narita, Yasuo Fukui, Toshiki Sato - Determination of varying speed of light from Black hole - https://arxiv.org/abs/2110.08809 - arXiv:2110.08809v2 Announce Type: replace-cross -Abstract: The Generalized Cosmological Time (GCT) framework offers an alternative phenomenological approach to addressing the Hubble tension and the observed time dilation of Type Ia supernovae, characterized by a background parameter b \simeq 0.04 and an associated cosmological scaling of fundamental constants. A key conceptual question is whether such a background evolution is compatible with the stability of local, gravitationally bound systems, in particular black holes. This work examines black hole thermodynamics within the GCT framework, focusing on the geometric compatibility between a locally static region and a time-dependent cosmological background. By matching a static interior spacetime to a GCT-FLRW exterior across a timelike boundary, it is shown that the Israel junction conditions allow for the coexistence of distinct time normalizations without introducing surface stresses. In this setting, the local interior naturally admits a unit lapse function, while the background evolution is encoded in the cosmological time gauge. The resulting separation of time normalizations implies that the effective GCT parameter governing local physics is observationally indistinguishable from b_{\mathrm{local}} \simeq 0. Under this geometric shielding, black hole thermodynamics reduces to its standard general relativistic form, and the Generalized Second Law is satisfied without imposing additional constraints on the background parameter b. These results indicate that the empirical stability of black hole thermodynamics does not directly constrain the global GCT evolution but instead reflects a geometric decoupling between local and cosmological time gauges. Black hole stability thus emerges as a consistency condition for geometric shielding, rather than as independent evidence for or against the underlying cosmological model. - oai:arXiv.org:2110.08809v2 - gr-qc - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross + Probing Heavily Obscured AGN in Major Galaxy Mergers Using the mm-X-ray Correlation + https://arxiv.org/abs/2601.15186 + arXiv:2601.15186v2 Announce Type: replace +Abstract: The study of heavily obscured supermassive black hole (SMBH) growth in late-stage galaxy mergers is challenging: column densities $N_{\mathrm{H}}>10^{24},\mathrm{cm}^{-2}$ can block most nuclear emission, leaving significant gaps in the SMBH growth census. Millimeter-wave continuum emission offers a potential window into this obscured phase, as it can trace Active Galactic Nuclei (AGN) activity through mechanisms less affected by dust extinction. In this work, we test whether the observed correlation between millimeter ($\sim200,\mathrm{GHz}$) and hard X-ray (14 - 150,keV) luminosities can be used to plausibly identify hidden AGN in local (Ultra)Luminous Infrared Galaxies (U)LIRGs, including systems hosting confirmed dual AGN. We identify three sources -- one confirmed AGN and two strong candidates -- presenting significant evidence of AGN activity. The confirmed dual AGN lie within $\sim3\sigma$ of the mm--X-ray correlation, suggesting this relation can be used to identify hidden pairs. By combining the position of each source relative to this correlation with independent star formation rate constraints, we propose a method to disentangle AGN and star formation contributions for sources with measured column densities. While our analysis is based on a small, heterogeneous local sample and relies on empirical scaling relations, these results indicate that millimeter continuum emission may provide a useful complementary diagnostic for obscured SMBH growth. ALMA observations at high angular resolutions are particularly valuable for this approach, while future facilities such as the ngVLA will be essential to test its robustness in larger and more distant samples. + oai:arXiv.org:2601.15186v2 + astro-ph.GA + Fri, 23 Jan 2026 00:00:00 -0500 + replace http://creativecommons.org/licenses/by/4.0/ - Seokcheon Lee + M. Droguett-Callejas, E. Treister, L. Barcos-Mu\~noz, M. Johnstone, F. E. Bauer, T. Kawamuro, N. Torres-Alb\`a, C. Ricci, M. Koss, Y. Song, A. Peca, A. Evans, J. Gonz\'alez - Strongly Interacting Dark Matter admixed Neutron Stars - https://arxiv.org/abs/2503.19691 - arXiv:2503.19691v3 Announce Type: replace-cross -Abstract: Dark matter may accumulate in neutron stars given its gravitational interaction and abundance. We investigate the modification of neutron star properties and confront them with the observations in the context of strongly-interacting dark matter scenario, specifically for a QCD-like theory with G$_2$ gauge group for which a first-principles equation-of-state from lattice calculations is available. We study the impact of various observational constraints and modeling of the QCD equation of state on the combined neutron stars. The results indicate that dark matter masses of a few hundred MeV to a few GeV are consistent with the latest observed neutron star properties. - oai:arXiv.org:2503.19691v3 + Constraining electromagnetic couplings of ultralight scalars from compact stars + https://arxiv.org/abs/2501.02286 + arXiv:2501.02286v2 Announce Type: replace-cross +Abstract: If an ultralight scalar interacts with the electromagnetic fields of a compact rotating star, then a long-range scalar field is developed outside the star. The Coulomb-like profile of the scalar field to the leading order is equivalent to an effective scalar charge on the star. In a binary star system, the scalar-induced charge would result in a long-range force between the stars, with the scalar field acting as the mediator. The scalar-photon interactions would modify Maxwell's equations for electromagnetic fields in vacuum, resulting in a modified dispersion relation. This could be observed as an apparent redshift for photons emitted by such sources. The scalar field would also induce additional electric and magnetic fields and hence affect the electromagnetic energy radiated from such compact objects. A scalar field sourced by time-varying electromagnetic fields can also carry away energy from a compact star in the form of radiation, and hence contribute to its spin-down luminosity. We constrain the scalar-photon coupling from the measurements of the electromagnetic radiation of a compact star and from its spin-down luminosity, using the Crab pulsar, the soft gamma repeater SGR 1806-20, and the gamma ray burst GRB 080905A. We also project the prospective bounds on the coupling from future measurements of the long-range force between two compact stars in a binary such as PSR J0737-3039, and from the apparent redshifts of compact stars. Future advances in precision-clock sensitivity and targeted observations of stars with strong surface magnetic fields, large radii, and low-frequency emission can substantially tighten these coupling limits. + oai:arXiv.org:2501.02286v2 hep-ph - astro-ph.HE - nucl-th - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.CO + gr-qc + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - Yannick Dengler, Suchita Kulkarni, Axel Maas, Kevin Radl + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Tanmay Kumar Poddar, Amol Dighe - Deflection angle in the strong deflection limit for static and axisymmetric spacetimes: Local curvature, matter fields, and quasinormal modes - https://arxiv.org/abs/2504.07906 - arXiv:2504.07906v4 Announce Type: replace-cross -Abstract: We investigate the deflection of photons in the strong deflection limit within static and axisymmetric spacetimes possessing reflection symmetry. As the impact parameter approaches its critical value, the deflection angle exhibits a logarithmic divergence. This divergence is characterized by a logarithmic coefficient and a constant offset, which we express in terms of the coordinate-invariant curvature quantities evaluated at the unstable circular photon orbit. The curvature contribution is encoded in the electric part of the Weyl tensor, reflecting tidal effects, and the matter contribution is encoded in the Einstein tensor, capturing the influence of local energy and pressure. We also express these coefficients using the Newman--Penrose scalars. By exploiting the relationship between the strong deflection limit and the quasinormal modes, we derive a new expression for the quasinormal mode frequency in the eikonal limit in terms of the curvature scalars. Our results provide a unified and coordinate-invariant framework that connects observable lensing features and quasinormal modes to the local geometry and matter distribution near compact objects. - oai:arXiv.org:2504.07906v4 - gr-qc + Constraining light dark matter in vector-scalar portals with COSI and AMEGO-X + https://arxiv.org/abs/2508.15891 + arXiv:2508.15891v2 Announce Type: replace-cross +Abstract: Detecting gamma-ray signals that could be due to dark matter (DM) particles would give us invaluable information about the nature of DM. In particular, gamma-ray lines could provide a way to measure the DM mass. The excellent energy resolution of the upcoming Compton Spectrometer and Imager (COSI) will allow us to probe underexplored regions of the DM parameter space while being sensitive to distinctive spectral features of potential DM signals. In this work, we consider a fermionic sub-GeV DM charged under a new U(1) gauge symmetry. Both the DM and the new gauge boson $Z'$ acquire mass from a new singlet scalar. The masses of the new particles in this class of vector-scalar portal models are naturally at the MeV scale, enabling detectable gamma-ray lines in the bandpasses of COSI and proposed missions such as the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X). We estimate the sensitivities of COSI and AMEGO-X to sub-GeV DM in this context, considering a B-L and a purely axial $Z'$ as benchmark examples. We find regions of the parameter space where COSI will provide leading constraints, beyond the strong CMB limits. On the other hand, AMEGO-X would probe most of the viable parameter space leading to continuum gamma rays. The implementation of our generic vector-scalar portal model in the Hazma toolkit is available at GitHub. + oai:arXiv.org:2508.15891v2 + hep-ph astro-ph.HE hep-th - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - 10.1103/ylrj-rm9j - Phys. Rev. D 113, 024036 (2026) - Takahisa Igata + Ma\'ira Dutra, Clarissa Siqueira, Tonia M. Venters - Bumblebee cosmology: The FLRW solution and the CMB temperature anisotropy - https://arxiv.org/abs/2504.10297 - arXiv:2504.10297v2 Announce Type: replace-cross -Abstract: We put into test the idea of replacing dark energy by a vector field against the cosmic microwave background (CMB) observation using the simplest vector-tensor theory, where a massive vector field couples to the Ricci scalar and the Ricci tensor quadratically. First, a remarkable Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) metric solution that is completely independent of the matter-energy compositions of the universe is found. Second, based on the FLRW solution as well as the perturbation equations, a numerical code calculating the CMB temperature power spectrum is built. We find that though the FLRW solution can mimic the evolution of the universe in the standard $\Lambda$CDM model, the calculated CMB temperature power spectrum shows unavoidable discrepancies from the CMB power spectrum measurements. - oai:arXiv.org:2504.10297v2 + Maximal GW amplitude from bubble collisions in supercooled phase transitions + https://arxiv.org/abs/2509.13402 + arXiv:2509.13402v2 Announce Type: replace-cross +Abstract: We extend analytic formulas for the gravitational-wave (GW) spectrum from first-order phase transitions to include cosmic expansion under the thin-wall and envelope approximations. We demonstrate that even for strongly supercooled transitions the GW amplitude is bounded from above. This conclusion is explicitly verified for several representative nucleation histories, including delta-function, power-law, and power-exponential types. Moreover, the spectral shape, amplitude, and peak frequency remain largely unaffected by the details of the nucleation rate once expressed in terms of the conformal variables evaluated at an appropriately defined characteristic collision time. + oai:arXiv.org:2509.13402v2 gr-qc astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.15302/frontphys.2026.036201 - Frontiers of Physics, 2026, volume 21, issue 3, 036201 - Rui Xu, Dandan Xu, Lars Andersson, Pau Amaro Seoane, Lijing Shao - - - Indirect searches for realistic sub-GeV Dark Matter models - https://arxiv.org/abs/2508.03819 - arXiv:2508.03819v3 Announce Type: replace-cross -Abstract: Indirect searches for Dark Matter (DM) particles with mass in the MeV -- GeV scale have received significant attention lately. Pair-annihilations of such DM particles in the Galaxy can give rise to (at the same time) MeV to GeV $\gamma$-rays via prompt emission, sub-GeV $e^\pm$ in cosmic-rays, as well as a broad photon spectrum ranging from $X$-rays to soft $\gamma$-rays, produced by the DM induced $e^\pm$ via inverse Compton scattering, bremsstrahlung and in-flight annihilation processes (collectively called `secondary emissions'). We focus on two representative realistic sub-GeV DM models, namely, the vector-portal kinetic-mixing model and the higgs-portal model, and perform a detailed study of the indirect detection constraints from existing $X$-rays, $\gamma$-rays and cosmic-ray observations, based on all of the above-mentioned signals. We also estimate the future prospects from the upcoming MeV photon telescope COSI, including all possible types of prompt and secondary emission signals. We compare our results with the constraints and (or) projections from cosmological and terrestrial observations. We find that, for both the sub-GeV DM models, the current observations constrain the annihilation cross-section at the level of $\langle \sigma v \rangle \lesssim 10^{-27} {\rm cm}^3/{\rm s}$, or lower for some specific mass ranges or under optimistic assumptions. Moreover, new unconstrained DM parameter space can be probed at the upcoming instruments like COSI, thanks to the inclusion of secondary photons which in many cases provide the dominant signal. - oai:arXiv.org:2508.03819v3 hep-ph - astro-ph.CO - astro-ph.GA - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Marco Cirelli, Arpan Kar, Halim Shaikh + 10.1016/j.physletb.2026.140157 + Phys.Lett.B 873 (2026) 140157 + Masaki Yamada - Discrete Chi-Square Method can model and forecast complex time series - https://arxiv.org/abs/2509.01540 - arXiv:2509.01540v4 Announce Type: replace-cross -Abstract: We show how intensive, large and accurate time series can allow us to see through time. Many phenomena have aperiodic and periodic components. An ideal time series analysis method would detect such trend and signal(-s) combinations. The widely-used Discrete Fourier Transform (DFT) and other frequency-domain parametric time series analysis methods have many application limitations constraining the trend and signal(-s) detection. We show that none of those limitations constrains our Discrete Chi-square Method (DCM) which can detect signal(-s) superimposed on an unknown trend. Our simulated time series analyses ascertain the revolutionary Window Dimension Effect (WDE): ``For any sample window $\Delta T$, DCM inevitably detects the correct $p(t)$ trend and $h(t)$ signal(-s) when the sample size $n$ and/or data accuracy $\sigma$ increase.'' The simulations also expose the DFT's weaknesses and the DCM's efficiency. The DCM's backbone is the Gauss-Markov theorem that the Least Squares (LS) is the best unbiased estimator for linear regression models. DCM can not fail because this simple method is based on the computation of a massive number of linear model LS fits. The Fisher-test gives the signal significance estimates and identifies the best DCM model from all alternative tested DCM models. The analytical solution for the non-linear DCM model is an ill-posed problem. We present a computational well-posed solution. The DCM can forecast complex time series. The best DCM model must be correct if it passes our Forecast-test. Our DCM is ideal for forecasting because its WDE spearhead is robust against short sample windows and complex time series. - oai:arXiv.org:2509.01540v4 - stat.ME - astro-ph.IM - Wed, 21 Jan 2026 00:00:00 -0500 + Asymptotics of spherical dynamos exhibiting a small-scale MAC balance + https://arxiv.org/abs/2509.21348 + arXiv:2509.21348v3 Announce Type: replace-cross +Abstract: Understanding the asymptotic behaviour of numerical dynamo models is critical for extrapolating results to the physical conditions that characterise terrestrial planetary cores. Here we investigate the behaviour of convection-driven dynamos reaching a MAC (magnetic-Archimedes-Coriolis) balance on the convective length scale and compare the results with non-magnetic convection cases. In particular, the dependence of physical quantities on the Ekman number, $Ek$, is studied in detail. The scaling of velocity dependent quantities is observed to be independent of the force balance and in agreement with quasi-geostrophic theory. The primary difference between dynamo and non-magnetic cases is that the fluctuating temperature is order unity in the former such that the buoyancy force scales with the Coriolis force. The MAC state yields a scaling for the flow speeds that is identical to the so-called CIA (Coriolis-inertia-Archimedes) scaling. There is an $O(Ek^{1/3})$ length scale present within the velocity field irrespective of the leading order force balance. This length scale is consistent with the asymptotic scaling of the terms of the governing equations and is not an indication that viscosity plays a dominant role. The peak of the kinetic energy spectrum and the ohmic dissipation length scale both exhibit an Ekman number dependence of approximately $Ek^{1/6}$, which is consistent with a scaling of $Rm^{-1/2}$, where $Rm$ is the magnetic Reynolds number. For the dynamos, advection remains comparable to, and scales similarly with, both inertia and viscosity, implying that nonlinear convective Rossby waves play an important role in the dynamics even in a MAC regime. + oai:arXiv.org:2509.21348v3 + physics.geo-ph + astro-ph.EP + astro-ph.SR + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Lauri Jetsu + Justin A. Nicoski, Andy Esseln, Chris Davies, Michael A. Calkins - Bouncing Cosmologies in modified gravity with space time torsion - https://arxiv.org/abs/2509.03508 - arXiv:2509.03508v3 Announce Type: replace-cross -Abstract: We explore the possibility of realizing a non-singular bounce in the early universe within the framework of modified gravity with spacetime torsion. In Einstein Cartan theory, torsion is embedded in the spacetime by adding an antisymmetric part in affine connection . We consider generalized version of the framework as $f(\bar{R})$, $\bar{R}$ being the scalar of the modified curvature tensor. $f(\bar{R})$ gravity is recast in Einstein frame as non-minimally coupled scalar tensor theory where the scalar field gets coupled with a rank 2 antisymmetric torsion field through derivative couplings. We investigate whether the introduction of three additional torsion-dependent terms in Einstein frame help to realize a bounce. We first explore this cosmological system in the background of a homogeneous and isotropic FRW spacetime but inclusion of the torsion terms are insufficient to produce a bounce in this symmetric setting. Motivated by this limitation, we relax the symmetry and generalize the background to include inhomogeneity and anisotropy. In this setup, the dynamics is modified in such a way that a bouncing solution is possible without invoking phantom fields or energy condition violations. We have found the exact solutions of all the fields and reconstructed the modified gravity form. We have addressed the behaviour of the fields under perturbation and investigated the stability of the solutions. Constraints on the model parameters have also been derived based on cosmological observations. - oai:arXiv.org:2509.03508v3 + Uncertainty in predicting the stochastic gravitational wave background from compact binary coalescences + https://arxiv.org/abs/2510.02163 + arXiv:2510.02163v3 Announce Type: replace-cross +Abstract: The stochastic gravitational wave background from compact binary coalescences is expected to be the first detectable stochastic signal via cross-correlation searches with terrestrial detectors. It encodes the cumulative merger history of stellar-mass binaries across cosmic time, offering a unique probe of the high-redshift Universe. However, predicting the background spectrum is challenging due to numerous modeling choices, each with distinct uncertainties. In this work, we present a comprehensive forecast of the astrophysical gravitational wave background from binary black holes, binary neutron stars, and neutron star-black hole systems. We systematically assess the impact of uncertainties in population properties, waveform features, and the modeling of the merger rate evolution. By combining all uncertainties, we derive credible bands for the background spectrum, spanning approximately an order of magnitude in the fractional energy density. These results provide thorough predictions to facilitate the interpretation of current upper limits and future detections. + oai:arXiv.org:2510.02163v3 gr-qc astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1140/epjc/s10052-025-15123-8 - European Physical Journal C 2025 - Sonej Alam, Somasri Sen, Soumitra Sengupta - - - Hyperons in Neutron Stars across the observed mass range: Insights from realistic $\Lambda$-N and $\Lambda$-$\Lambda$ interactions within a Microscopic Framework - https://arxiv.org/abs/2509.12881 - arXiv:2509.12881v2 Announce Type: replace-cross -Abstract: We investigate the equation of state (EOS) and macroscopic properties of neutron stars (NSs) and hyperonic stars within the framework of the lowest order constrained variational (LOCV) method, extended to include interacting $\Lambda$ hyperons. The nucleon-nucleon interaction is modeled using the AV18 potential supplemented by Urbana three-body forces, while $\Lambda N$ and $\Lambda \Lambda$ interactions are described by realistic spin- and parity-dependent potentials fitted to hypernuclear data. Cold, charge-neutral, and $\beta$-equilibrated matter composed of neutrons, protons, electrons, muons, and $\Lambda$ hyperons is considered. We compute particle fractions, chemical potentials, the EOS, speed of sound, tidal deformability, and stellar structure by solving the Tolman-Oppenheimer-Volkoff equations, and compare our results with recent NICER and gravitational-wave observations. The inclusion of $\Lambda$ hyperons leads to EOS softening, reducing the maximum NS mass from $2.34M_\odot$ to $2.07M_\odot$, while keeping it consistent with the $2M_\odot$ mass constraint. At $1.4M_\odot$, the model satisfies observational limits on radius and tidal deformability, with the $\Lambda$ onset occurring below this mass. Comparison with other microscopic and relativistic mean-field models shows that our EOS remains consistent with the allowed pressure-energy density range, while also permitting even canonical-mass NSs of about $1.4M_{\odot}$ to accommodate hyperons. These results suggest that hyperons can appear in NSs across the observed mass range without violating current astrophysical constraints, and that the extended LOCV method provides a consistent, microscopic approach to modeling dense hypernuclear matter. - oai:arXiv.org:2509.12881v2 - nucl-th astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3847/1538-4357/ae18d0 - ApJ 997 26 (2026) - Ali Mohammad Ali Looee, Mahboubeh Shahrbaf, Hamid Reza Moshfegh + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Michael Ebersold, Tania Regimbau - Charged particle dynamics in singular spacetimes: hydrogenic mapping and curvature-corrected thermodynamics - https://arxiv.org/abs/2509.16289 - arXiv:2509.16289v2 Announce Type: replace-cross -Abstract: We analyze the dynamics of charged test particles in a singular, horizonless spacetime arising as the massless limit of a charged wormhole in the Einstein--Maxwell--Scalar (EMS) framework. The geometry, sustained solely by an electric charge $Q$, features an infinite sequence of curvature singularity shells, with the outermost at \( r_* = \frac{2|Q|}{\pi} \) acting as a hard boundary for nonradial motion, while radial trajectories can access it depending on the particle charge-to-mass ratio \( |q|/m \). Exploiting exact first integrals, we construct the effective potential and obtain circular orbit radii, radial epicyclic frequencies, and azimuthal precession rates. In the weak-field limit (\( r \gg |Q| \)), the motion reduces to a Coulombic system with small curvature-induced retrograde precession. At large radii, the dynamics maps to a hydrogenic system, with curvature corrections inducing perturbative energy shifts. Approaching \( r_* \), the potential diverges, producing hard-wall confinement. Curvature corrections also modify the spectral thermodynamics, raising energies and slightly altering entropy and heat capacity. Our results characterize the transition from Newtonian-like orbits to strongly confined, curvature-dominated dynamics. - oai:arXiv.org:2509.16289v2 + Pulsar timing array analysis in a Legendre polynomial basis + https://arxiv.org/abs/2510.05913 + arXiv:2510.05913v3 Announce Type: replace-cross +Abstract: We use Legendre polynomials, previously employed in this context by Lee et al. [1], van Haasteren and Levin [2], and Pitrou and Cusin [3], to model signals in pulsar timing arrays (PTA). These replace the (Fourier mode) basis of trigonometric functions normally used for data analysis. The Legendre basis makes it simpler to incorporate pulsar modeling effects, which remove constant-, linear-, and quadratic-in-time terms from pulsar timing residuals. In the Legendre basis, this zeroes the amplitudes of the the first three Legendre polynomials. We use this basis to construct an optimal quadratic cross-correlation estimator $\widehat{\mu}$ of the Hellings and Downs (HD) correlation and compute its variance $\sigma^2_{\widehat{\mu}}$ in the way described by Allen and Romano [4]. Remarkably, if the gravitational-wave background (GWB) and pulsar noise power spectra are (sums of) power laws in frequency, then in this basis one obtains analytic closed forms for many quantities of interest. + oai:arXiv.org:2510.05913v3 gr-qc - astro-ph.HE - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Abdullah Guvendi, Semra Gurtas Dogan, Omar Mustafa, Hassan Hassanabadi - - - The Nature of Turbulence at Sub-Electron Scales in the Solar Wind - https://arxiv.org/abs/2509.17061 - arXiv:2509.17061v2 Announce Type: replace-cross -Abstract: The nature of turbulence at sub-electron scales has remained an open question, central to understanding how electrons are heated in the solar wind. This is primarily because spacecraft measurements have been limited to magnetic field fluctuations alone. We resolve this by deriving new high-resolution density fluctuations from spacecraft potential measurements of Parker Solar Probe resolving scales smaller than the electron gyro-radius ($\rho_e$). A systematic comparison of the density and magnetic spectra shows that both steepen near the electron scales. Notably, the density spectrum exhibits slopes close to $-10/3$, while the magnetic spectrum becomes consistently steeper than the density spectrum at scales smaller than $\rho_e$, indicating that the turbulence becomes electrostatic. These results are consistent with theoretical predictions of an electron entropy cascade, which may explain the irreversible dissipation of turbulent energy at sub-$\rho_e$ scales. The magnetic spectrum, however, is not as steep as expected for the electron entropy cascade, which may be due to limited signal-to-noise ratio and the presence of weakly damped electromagnetic fluctuations near $\rho_e$. - oai:arXiv.org:2509.17061v2 - physics.space-ph - astro-ph.SR - physics.plasm-ph - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.CO + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Shiladittya Mondal, Christopher H. K. Chen, Davide Manzini + Bruce Allen, Arian L. von Blanckenburg, Ken D. Olum - Anderson self-localization of light in pair plasmas - https://arxiv.org/abs/2509.20594 - arXiv:2509.20594v2 Announce Type: replace-cross -Abstract: We demonstrate that in pair plasma weakly nonlinear electromagnetic waves, $a_0 \leq 1$, experience Anderson self-localization. The beat between the driver and a back-scattered wave creates charge-neutral, large random density fluctuations $\delta n/n_0 \gg 1$, and corresponding fluctuations of the dielectric permittivity $\epsilon$ (random plasma density grating). Propagating in quasi-1D, waves in a medium with spatially random self-created fluctuations of dielectric permeability experience localization. {In the linear regime, the instability can be classified as Induced Brillouin Scattering; it is described by the parameter $\rho _L = \left( a_0 { \omega_{p}/ }{\omega}\right)^{2/3} \leq 1 $, related to the Pierce parameter of Free Electron Lasers. In the cold case, the growth rate is $\Gamma \approx \rho _{L} \omega$ ($a_0 $ is laser nonlinearity parameter, $\omega_p$ is plasma frequency, $\omega$ is the laser frequency). } Anderson self-localization of light leads to (i) reflection of EM waves by the under-dense pair plasma; (ii) a wave already present inside the plasma separates into bright trapped pockets and dark regions. Mild initial thermal spread with $\Theta \equiv k_B T/(m_e c^2) \approx a_0^2$, restores wave propagation by suppressing the seeds of parametrically unstable density fluctuations. A circularly polarized driver produces linearly polarized structures, with position angle varying randomly between the bright pulses. Time-variability of the resulting density structures does not suppress localization due to remaining corrections (not white noise). We discuss possible applications to astrophysical Fast Radio Bursts. - oai:arXiv.org:2509.20594v2 - physics.plasm-ph + Reconstructing and resampling: a guide to utilising posterior samples from gravitational wave observations + https://arxiv.org/abs/2510.11197 + arXiv:2510.11197v2 Announce Type: replace-cross +Abstract: The LIGO, Virgo, and KAGRA (LVK) gravitational-wave observatories have opened new scientific research in astrophysics, fundamental physics, and cosmology. The collaborations that build and operate these observatories release the interferometric strain data as well as a catalogue of observed signals with accompanying Bayesian posterior distributions. These posteriors, in the form of equally-weighted samples, form a dataset that is used by a multitude of further analyses seeking to constrain the population of merging black holes, identify lensed pairs of signals, and much more. However, many of these analyses rely, often implicitly, on the ability to reconstruct the likelihood and prior from the inputs to the analysis and apply resampling (a statistical technique to generate new samples varying the underlying analysis assumptions). In this work, we first provide a guide on how to reconstruct and modify the posterior density accurately from the inputs for analyses performed with the Bilby inference library. We then demonstrate and compare resampling techniques to produce new posterior sample sets and discuss Pareto-smoothing to improve the efficiency. Finally, we provide examples of how to use resampling to study observed gravitational-wave signals. We hope this guide provides a useful resource for those wishing to use open data products from the LVK for gravitational-wave astronomy. + oai:arXiv.org:2510.11197v2 + gr-qc astro-ph.HE - cond-mat.dis-nn - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Maxim Lyutikov (Purdue University), Victor Gurarie (University of Colorado) - - - Automating Sensor Characterization with Bayesian Optimization - https://arxiv.org/abs/2509.21661 - arXiv:2509.21661v2 Announce Type: replace-cross -Abstract: The development of novel instrumentation requires an iterative cycle with three stages: design, prototyping, and testing. Recent advancements in simulation and nanofabrication techniques have significantly accelerated the design and prototyping phases. Nonetheless, detector characterization continues to be a major bottleneck in device development. During the testing phase, a significant time investment is required to characterize the device in different operating conditions and find optimal operating parameters. The total effort spent on characterization and parameter optimization can occupy a year or more of an expert's time. In this work, we present a novel technique for automated sensor characterization that aims to accelerate the testing stage of the development cycle. This technique leverages closed-loop Bayesian optimization (BO), using real-time measurements to guide parameter selection and identify optimal operating states. We demonstrate the method with a novel low-noise CCD, showing that the machine learning-driven tool can efficiently characterize and optimize operation of the sensor in a couple of days without supervision of a device expert. - oai:arXiv.org:2509.21661v2 - physics.ins-det astro-ph.IM - cs.LG - Wed, 21 Jan 2026 00:00:00 -0500 + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - J. Cuevas-Zepeda, C. Chavez, J. Estrada, J. Noonan, B. D. Nord, N. Saffold, M. Sofo-Haro, R. Spinola e Castro, S. Trivedi + Gregory Ashton - High Reheating Temperature without Axion Domain Walls - https://arxiv.org/abs/2509.24812 - arXiv:2509.24812v2 Announce Type: replace-cross -Abstract: We investigate a cosmological scenario in which the Peccei-Quinn (PQ) symmetry remains broken in the entire history of the Universe, thereby avoiding the formation of axion strings and domain walls. Contrary to the conventional expectation, it is demonstrated that appropriately chosen scalar interactions are able to keep the PQ symmetry broken at arbitrarily high temperatures. We carefully examine the finite-temperature effective potential in a model with two PQ breaking scalar fields. The existence of flat directions plays a vital role in suppressing axion isocurvature perturbations during inflation by stabilizing a PQ field at a large field value. The viable parameter space consistent with theoretical and observational constraints is identified. Our scenario provides a minimal path for PQ symmetry breaking that addresses both the axion domain wall and isocurvature problems while permitting arbitrarily high reheating temperatures accommodating high-scale baryogenesis scenarios such as thermal leptogenesis. - oai:arXiv.org:2509.24812v2 - hep-ph - astro-ph.CO - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 + Development and Testing of a Modular Large-Area Cosmic Ray Telescope Using Scintillator-Fiber Hybrid Design for Millimeter-Level Muon Tracking + https://arxiv.org/abs/2511.16290 + arXiv:2511.16290v2 Announce Type: replace-cross +Abstract: Cosmic-ray muons, owing to their high penetration power and abundance, have been widely employed as a natural probe in experimental particle physics. We developed a meter-scale cosmic-ray muon telescope, consisting of two parallel super-layers (1 m $\times$ 1 m) separated vertically by one meter. A super-layer is composed of two orthogonal detection layers, of which each consists of eighteen modules arranged in parallel and packed closely together. A module consists of a plastic scintillating bar precisely aligned and stacked on top of an underlying scintillating fiber mat. The telescope employs a detection scheme combining scintillating bars and fibers to meet the requirement of spatial resolution and to reduce the number of readout electronic channels. + This article presents the comprehensive development of the telescope, encompassing its geometric design, data acquisition system, and performance evaluation. Experimental results show that the telescope achieves a position resolution better than 2 mm and an overall detection efficiency of $\sim$85%. The innovative design keeps the manufacturing cost low while maintaining high spatial resolution and detection efficiency. + oai:arXiv.org:2511.16290v2 + hep-ex + astro-ph.IM + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - 10.1016/j.physletb.2026.140177 - Shota Nakagawa, Yuichiro Nakai, Yu-Cheng Qiu, Lingyun Wang, Yaoduo Wang + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yan Niu, Anqing Wang, Xiangxiang Ren, Dong Liu, Meng Wang - Implications of $f(R)$ gravity on late-time cosmic structure growth through a complete description of density perturbations - https://arxiv.org/abs/2510.19569 - arXiv:2510.19569v2 Announce Type: replace-cross -Abstract: We provide insight about the full form of the equations for matter density perturbations and the scalar Bardeen metric potentials in general $f(R)$ theories of gravity. When considering viable modifications to the standard $\Lambda$CDM background, the full scale-dependent equations for the metric perturbations are provided and are shown to match the ones obtained with the quasistatic approximation. We investigate the impact of the $n=2$ Hu-Sawicki model on the late-time growth of structures. We find that updated late-time growth of structure data imposes $|f_{R_0}|\lesssim10^{-6}-10^{-5}$ and thus conclude that the Hu-Sawicki $f(R)$ model contributes no significant phenomenology at both background and perturbative level beyond the effective cosmological constant encompassed in its definition. This conclusion points to the survival of the present tension between early and late measurements of $\sigma_8$, as the Hu-Sawicki model can only worsen this issue or at best reproduce the results from the current concordance cosmological model. The generalized perturbative method showcased in this work can be applied to more elaborate $f(R)$ models to isolate genuine higher-order signatures beyond the quasistatic approximation. - oai:arXiv.org:2510.19569v2 + Multipole moments do not uniquely characterize spacetimes beyond general relativity + https://arxiv.org/abs/2511.22405 + arXiv:2511.22405v2 Announce Type: replace-cross +Abstract: Spacetimes in general relativity can be uniquely decomposed into a set of multipole moments. Given the usefulness of moments in the categorization of radiation patterns, tidal deformations, and other phenomena associated with compact objects, a number of studies have explored their construction in beyond-Einstein theories of gravity. It is shown here that uniqueness does not necessarily extend across theories: by comparing a few static and spherically-symmetric solutions in different theories, we find that two distinct objects can possess the same Geroch-Hansen moments. Moreover, two metrics can match and yet take different moments. Implications of this result are explored in the context of black-hole shadows and ``universal'' relations hinging on moment computations. + oai:arXiv.org:2511.22405v2 gr-qc - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.HE + hep-th + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - 10.1016/j.dark.2026.102232 - Miguel Barroso Varela, \'Alvaro de la Cruz-Dombriz + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Arthur G. Suvorov, George Pappas - Conserved Quantities in Expanding G\"odel Cosmology - https://arxiv.org/abs/2511.00238 - arXiv:2511.00238v5 Announce Type: replace-cross -Abstract: At linear order we study perturbations to a G\"odel background spacetime which includes expansion in addition to rotation. We investigate the transformation behaviour of these perturbations under gauge transformations and construct gauge invariant quantities. Using the perturbed energy conservation equation we find that there are conserved quantities in Expanding G\"odel (EG) Cosmology, in particular a spatial metric trace perturbation, {\zeta} SMTP , which is conserved on large scales for pressureless dust. We finally extend our discussion to a perfect fluid matter content to also obtain conserved quantities in this context. - oai:arXiv.org:2511.00238v5 + Two-Dimensional Pulsar Distance Inference from Nanohertz Gravitational Waves + https://arxiv.org/abs/2512.10729 + arXiv:2512.10729v2 Announce Type: replace-cross +Abstract: Pulsar timing arrays (PTAs) are limited in localizing nanohertz continuous gravitational waves (CGWs) by uncertainties in pulsar distances. We introduce a method to infer pulsar distances in two dimensions, using phase information from the pulsar terms of multiple CGW sources. Our approach can enhance distance precision and, in some cases, achieve order-of-magnitude improvements relative to existing one-dimensional distance-inference methods. Using simulations of an SKA-era PTA with realistic parallax-based distance priors, we demonstrate that pulsars at $\sim 1$ kpc can achieve sub-parsec distance precision with only a few CGW sources. Such improvements in pulsar-distance precision have important implications for CGW host-galaxy identification and multimessenger observational prospects. + oai:arXiv.org:2512.10729v2 gr-qc astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.HE + hep-ph + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - 10.1103/bcdm-3nd7 - Alexander Leithes + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Si-Ren Xiao, Ji-Yu Song, Yue Shao, Ling-Feng Wang, Jing-Fei Zhang, Xin Zhang - Time-dependent flux backgrounds in type IIB supergravity - https://arxiv.org/abs/2512.19793 - arXiv:2512.19793v2 Announce Type: replace-cross -Abstract: We analytically construct families of type IIB supergravity backgrounds in ten dimensions in which the four-dimensional metric is time dependent, while the six-dimensional internal space is an arbitrary compact Calabi-Yau manifold (with no restriction on holonomy) up to an overall time-dependent scale factor. Our solutions include cases with all fluxes (three-form and self-dual five-form) switched on, as well as cases with subsets of these fluxes, together with a time-dependent axiodilaton in most cases. These constructions require no local sources. We show that the associated energy-momentum tensors (both 10D and the resulting 4D effective) satisfy the null, weak, strong, and dominant energy conditions. In our explicit constructions, the Ricci scalar of the four-dimensional Einstein frame metric is negative; such backgrounds may find applications to anisotropic or FLRW cosmologies in the early universe. We also revisit the Maldacena--Nu\~nez no-go analysis, incorporating new elements that appear in our constructions, namely an overall noncompact spacetime-dependent scale factor multiplying the internal metric, and field strengths with components partially covering the noncompact directions. We argue that, with these generalizations, a four-dimensional Einstein-frame metric with positive Ricci scalar cannot be ruled out by such an analysis. - oai:arXiv.org:2512.19793v2 - hep-th - astro-ph.CO + A Framework for Lorentz-Dirac Dynamics and Post-Newtonian Interaction of Radiating Point Charges + https://arxiv.org/abs/2512.18637 + arXiv:2512.18637v3 Announce Type: replace-cross +Abstract: We examine classical radiation reaction by combining the covariant Lorentz--Dirac formulation, its Landau--Lifshitz (LL) order reduction, and a post-Newtonian (PN) Hamiltonian treatment of interacting and radiating charges. After reviewing the LL reduction and its removal of runaway and preacceleration behavior, we verify energy balance in several relativistic single-particle scenarios by demonstrating agreement between the LL Larmor power and the loss of mechanical energy. We then construct an N-body framework based on the conservative Darwin Hamiltonian supplemented with the leading 1.5PN radiation--reaction term. Numerical simulations of charge-neutral binary systems of both symmetric and asymmetric mass configurations show orbital decay, circularization, and monotonic Hamiltonian decrease consistent with dipole radiative losses. The resulting framework provides a simple analogue of gravitational PN radiation reaction and a tractable system for studying dissipative and potentially chaotic electromagnetic dynamics. + oai:arXiv.org:2512.18637v3 gr-qc - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.HE + hep-th + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Ahmed Rakin Kamal, Ratul Mahanta + Suhani Verma, Siddarth Mediratta, Nanditha Kilari, Prakhar Nigam, Ishaan Singh, Daksh Tamoli, Aakash Palakurthi, Valluru Ishaan, Tanmay Golchha, Sanjay Raghav R, Sugapriyan S, Yash Narayan, Pasupuleti Devi, Prathamesh Kapase, G Prudhvi Raj, Lakshya Sachdeva, Shreya Meher, K Nanda Kishore, G Keshav, Jetain Chetan, Rickmoy Samanta - Taxonomy of periodic orbits and gravitational waves in a deformed Schwarzschild black hole spacetime - https://arxiv.org/abs/2601.00550 - arXiv:2601.00550v3 Announce Type: replace-cross -Abstract: In this paper, we investigate periodic orbits of test particles around a deformed Schwarzschild black hole and the resulting gravitational waves. Firstly, we examine the properties of circular orbits and find that circular orbits could disappear when the deformation is large enough. Then, using an orbital taxonomy, we characterize various periodic orbits with a set of triples, which describes the zoom-whirl behaviours. We also calculate the gravitational waveform signals generated by different periodic orbits, revealing the influence of the deformation on the gravitational wave, which can be potentially picked up by future space-based detectors. - oai:arXiv.org:2601.00550v3 + Calibration Method of Spacecraft-Inertial Sensor Center-of-Mass Offset for the Taiji Gravitational Wave Detection Mission under Science Mode + https://arxiv.org/abs/2512.20468 + arXiv:2512.20468v2 Announce Type: replace-cross +Abstract: Accurately calibrating the center-of-mass (CoM) offset between the spacecraft (SC) and the inertial sensor test mass (TM) is crucial for space-based gravitational-wave (GW) antennas, such as LISA and Taiji. Current calibration methods require additional spacecraft maneuvers that disrupt science data continuity and inter-satellite links, compromising the coherence of gravitational wave signals. Here, we present a maneuver-free calibration scheme that directly estimates the CoM offset vector using only standard science-mode measurements from inertial sensors, interferometers, and differential wavefront sensors. By embedding the CoM offset induced coupling acceleration as an extended state in a model-based adaptive Kalman filter, we achieve estimation accuracy of 0.01-1.5 mm across all axes with a maximum error below 1%. This approach enables continuous, high-precision calibration during nominal observation runs, ensuring continuous and coherent gravitational wave data collection while maintaining the required precision, and also facilitating advanced DFACS functions such as performance evaluations and fault diagnosis. For LISA-like missions, where data continuity is paramount for detecting faint gravitational wave signals, this method will enhance scientific output and reliability. + oai:arXiv.org:2512.20468v2 gr-qc - astro-ph.HE - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.IM + physics.ins-det + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Zhutong Hua, Zhen-Tao He, Jiageng Jiao, Jing-Qi Lai, Yu Tian + Haoyue Zhang, Dong Ye, Peng Xu, Yunhai Geng, Li-E Qiang, Ziren Luo - From the Wavefunction of the Universe to In-In-Correlators: A Perturbative Map to All Orders - https://arxiv.org/abs/2601.00992 - arXiv:2601.00992v2 Announce Type: replace-cross -Abstract: Both the Wavefunction of the Universe and the Schwinger-Keldysh in-in formalism are central tools for analyzing primordial cosmological observables, such as equal-time correlation functions. While their conceptual equivalence is well established, a systematic and explicit map between their diagrammatic expansions has remained elusive. In this article, I construct such a map by analyzing the relation between the two frameworks at the diagrammatic level. I show that diagrams contributing to correlation functions in the Wavefunction of the Universe approach can be uniquely reorganized into Schwinger-Keldysh diagrams. This correspondence holds to all orders in perturbation theory, including arbitrary numbers of interaction vertices and loops. - oai:arXiv.org:2601.00992v2 - hep-th - astro-ph.CO - gr-qc + Resonant Photon-Axion Mixing Driven by Dark Matter Oscillations + https://arxiv.org/abs/2601.02115 + arXiv:2601.02115v2 Announce Type: replace-cross +Abstract: Wave propagation in periodically time-dependent media can exhibit driven mode conversion that is absent in static or adiabatic descriptions. We show that photon propagation through a coherent axion dark matter background provides a natural realization of such driven dynamics. In the presence of a magnetic field, the oscillating axion field acts as a coherent temporal drive, inducing resonant photon-axion conversion when the mismatch between their dispersion relations is compensated by integer harmonics of the axion oscillation frequency, $\Delta_\gamma - \Delta_a \approx n m_a$ with $n \in \mathbb{Z}$. This driven resonance enables efficient mixing far from the conventional level-crossing regime and disappears entirely upon time averaging, explaining why it is missed in standard treatments. The process constitutes a unitary mode-conversion phenomenon that preserves the axion dark matter number density and is distinct from parametric instabilities or axion decay. A systematic description is naturally provided by Floquet theory. We develop a general framework for photon propagation in oscillating axion backgrounds and show that the resulting resonant mixing leads to characteristic polarization signatures, with potential implications for astrophysical observations such as blazar polarization. + oai:arXiv.org:2601.02115v2 hep-ph - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Gonzalo A. Palma - - - Symmetries of cosmological perturbations: The residual low-multipole ambiguity - https://arxiv.org/abs/2601.04144 - arXiv:2601.04144v2 Announce Type: replace-cross -Abstract: In cosmology, long-wavelength modes are related to large-gauge transformations (LGT), i.e. changes of coordinates that modify the physical geometry of the cosmological patch. These LGTs stand as bona-fide symmetries of cosmological perturbation theory with various applications, from consistency relations constraining cosmological correlators to non-linear conservation laws in the separate-universe approach. In this work, we revisit LGTs and derive two new results. First, we show that the global symmetries already identified in the literature can be extended to local infinite-dimensional symmetries. The associated generators depend on arbitrary functions of time, and generate low-multipole modes that modify the mean curvature energy and the angular momentum of the patch, demonstrating their physical nature. We propose to interpret these low-multipole soft modes as a new cosmological-frame ambiguity that needs to be fixed prior to evaluating cosmological observables. Second, we demonstrate that the adiabatic cosmological perturbations generated by LGTs deform but preserve all the explicit and hidden Killing symmetries of the background geometry. As such, long-wavelength modes stand as a concrete example of algebraically-special cosmological perturbations of Petrov-type O, and inherit the conformal group as isometries and a set of four deformed Killing-Yano tensors and their associated Killing tensors. This opens the possibility to study their effect on cosmological observables in a fully analytic manner. - oai:arXiv.org:2601.04144v2 - gr-qc - astro-ph.CO - Wed, 21 Jan 2026 00:00:00 -0500 + astro-ph.HE + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - Jibril Ben Achour, Etera Livine, Vincent Vennin + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Run-Min Yao, Xiao-Jun Bi, Peng-Fei Yin, Qing-Guo Huang - DC response of an interferometer topology with an L-shaped cavity: a tabletop study - https://arxiv.org/abs/2601.09764 - arXiv:2601.09764v2 Announce Type: replace-cross -Abstract: A new interferometer topology for kilohertz gravitational-wave detection was recently proposed in [Zhang et al. Phys. Rev. X 13, 021019 (2023)]. The design is based on an L-shaped optical cavity pumped through a Sagnac-like vortex. We report a tabletop experiment that characterizes the interferometer's optical response near DC. When the laser frequency is locked to the resonance of the L-shaped cavity, we observe that the cavity input coupler becomes effectively transparent, yielding a simple Michelson-like response. Moreover, the Sagnac vortex separates into upper and lower paths, which behave as two independent pumping paths driving the cavity. These observations are in agreement with theoretical predictions. Our results provide an intuitive physical picture of this interferometer topology and offer insight into its lock acquisition strategy. - oai:arXiv.org:2601.09764v2 - physics.ins-det - astro-ph.IM - gr-qc - physics.optics - Wed, 21 Jan 2026 00:00:00 -0500 + On flying through the base of a pseudo-streamer + https://arxiv.org/abs/2601.03620 + arXiv:2601.03620v2 Announce Type: replace-cross +Abstract: Near the 10 solar radius perihelion of Parker Solar Probe orbit 24, a confined region containing an enhanced plasma density of 25,000 particles per cubic centimeter and broadband electrostatic waves was encountered. The solar wind velocity of 200 kilometers per second and ion temperature of 25 eV were significantly reduced as compared to their values in the ambient solar wind. These anomalous plasma conditions were observed on closed magnetic field lines, as determined from observations of the suprathermal electron strahl. Because the polarity of the radial magnetic field did not change sign on the two sides of the crossing and the crossed region contained a double-peaked plasma structure, the spacecraft must have passed through the base of a pseudo-streamer whose structure extended out to 10 solar radii. In the plasma frame, an electric field as large as 400 millivolts per meter was detected during the crossing. The current associated with this electric field was less than one milliampere per square meter, corresponding to a drift velocity less than 2.5 kilometers per second. It also contained a turbulent plasma with density fluctuations divided by density as large as 0.3, suggesting that the resistive term in the generalized ohm's law was significant. Also, the density as a function of time had a non-zero slope when the electric field was non-zero, suggesting that the pressure gradient term also mattered. As compared to earlier remote sensing and theoretical results, it is surprising that the plasma in this pseudo-streamer had a remarkably low flow velocity and that the pseudo-streamer base extended out to 10 solar radii. + oai:arXiv.org:2601.03620v2 + physics.space-ph + astro-ph.SR + physics.plasm-ph + Fri, 23 Jan 2026 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Junlang Li, Jiehong Huang, Xinyao Guo, Haixing Miao, Yuchao Chen, Xiaoman Huang, Yuan Pan, Chenjie Zhou, Raffaele Flaminio, Jameson Graef Rollins, Bram Slagmolen, Fan Zhang, Teng Zhang, Mengyao Wang - - - Effects of spontaneous Lorentz Symmetry breaking on Letelier-AdS charged black holes within Kalb-Ramond gravity - https://arxiv.org/abs/2601.10303 - arXiv:2601.10303v2 Announce Type: replace-cross -Abstract: In this study, we investigate the geodesic motion of massless particles -- specifically photons -- in the spacetime of a charged anti-de Sitter (AdS) black hole (BH) surrounded by a cloud of strings (CoS) within the framework of Kalb-Ramond (KR) gravity. We analyze the effective potential that governs photon trajectories, explore the properties and location of the photon sphere (PS), and examine the effective radial force acting on photons. The resulting BH shadow is also studied, highlighting the roles of both the CoS parameter $\alpha$ and the KR field parameter $\ell$ in shaping its geometry. We constrain these parameters using observational data from M87* and Sgr A* obtained by the Event Horizon Telescope (EHT). Furthermore, we extend our investigation to the motion of neutral test particles in the same gravitational background. By examining the impact of the CoS and KR field, we show how these additional fields modify the dynamics relative to standard charged BH scenarios. Finally, we study the fundamental frequencies associated with quasiperiodic oscillations (QPOs) of test particles, demonstrating how these frequencies are affected by the presence of the CoS and KR field. Our results reveal the rich structure of AdS-BH spacetimes influenced by string clouds and antisymmetric tensor fields, with potential observational consequences in gravitational wave and BH imaging astronomy. - oai:arXiv.org:2601.10303v2 - gr-qc - astro-ph.HE - hep-th - Wed, 21 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Faizuddin Ahmed, Ahmad Al-Badawi, \.Izzet Sakall{\i} + Forrest Mozer, Oleksiy Agapitov, Kyungeun Choi, Andrii Voshchepynets