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410149dbc978974598acd019106bba6b21a173e3bc53aa14ff4fa9155173cd17
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2026-01-13T00:00:00-05:00
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Omnibus goodness-of-fit tests based on trigonometric moments
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arXiv:2507.18591v2 Announce Type: replace-cross Abstract: We propose a new omnibus goodness-of-fit test based on trigonometric moments of probability-integral-transformed data. The test builds on the framework of the LK test introduced by Langholz and Kronmal [J. Amer. Statist. Assoc. 86 (1991), 1077-1084], but fully exploits the covariance structure of the associated trigonometric statistics. As a result, our test statistic converges under the null hypothesis to a $\chi_2^2$ distribution, even in the presence of nuisance parameters, yielding a well-calibrated rejection region. We derive the exact asymptotic covariance matrix required for normalization and propose a unified approach to computing the LK normalizing scalar. The applicability of both the proposed test and the LK test is substantially expanded by providing implementation details for 11 families of continuous distributions, covering most commonly used parametric models. Simulation studies demonstrate accurate empirical size, close to the nominal level, and strong power properties, yielding fully plug-and-play procedures. Further insight is provided by an analysis under local alternatives. The methodology is illustrated using surface temperature forecast errors from a numerical weather prediction model.
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https://arxiv.org/abs/2507.18591
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Academic Papers
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9b326291b489041fc230480f49510208842f877390828af11fb2add78003353e
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2026-01-13T00:00:00-05:00
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GSO Defects: IIA/IIB Walls and the Surprisingly Stable $\mathrm{R}7$-Brane
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arXiv:2507.21210v2 Announce Type: replace-cross Abstract: The recently proposed Swampland Cobordism Conjecture predicts the existence of new non-supersymmetric objects which supplement the spectrum of low-energy gravitational effective field theories. In this paper, we study a subset of these defects related to the GSO projection on the string worldsheet. These include the predicted domain wall between Type IIA and IIB superstring theories and the newly-discovered $\mathrm{R}7$-brane. We study these defects in two different ways: via long-string probes and target-space effective field theory. We find that the $\mathrm{R}7$-brane can be identified with a collapsed cylindrical configuration of the IIA/IIB wall, and further, that the $\mathrm{R}7$-brane is stable, in contrast to previous expectations. Moreover, we argue that BPS D-branes pulled across the IIA/IIB wall become non-BPS D-branes, which we identify with fluxbrane configurations. We show that the non-BPS D-branes of either Type II theory are charged under a $\mathbb{Z}_2$ remnant of the Ramond-Ramond potentials of the other, which we identify with the mod 2 reduction of the Ramond-Ramond fluxes. Similar considerations provide a complementary perspective on the Heterotic ${\mathfrak{so}(32)}$ S-duals of known non-BPS 7- and 8-branes in Type I string theory.
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https://arxiv.org/abs/2507.21210
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9106132bdb70aab6fad7a7864e87651c344732f6c511765d1781fc001c0dc654
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2026-01-13T00:00:00-05:00
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Simulating Posterior Bayesian Neural Networks with Dependent Weights
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arXiv:2507.22095v3 Announce Type: replace-cross Abstract: We consider fully connected and feedforward deep neural networks with dependent and possibly heavy-tailed weights, as introduced in Lee et al. 2023, to address limitations of the standard Gaussian prior. It has been proved in Lee et al. 2023 that, as the number of nodes in the hidden layers grows large, according to a sequential and ordered limit, the law of the output converges weakly to a Gaussian mixture. Among our results, we present sufficient conditions on the model parameters (the activation function and the associated L\'evy measures) which ensure that the sequential limit is independent of the order. Next, we study the neural network through the lens of the posterior distribution with a Gaussian likelihood. If the random covariance matrix of the infinite-width limit is positive definite under the prior, we identify the posterior distribution of the output in the wide-width limit according to a sequential regime. Remarkably, we provide mild sufficient conditions to ensure the aforementioned invertibility of the random covariance matrix under the prior, thereby extending the results in L. Carvalho et al. 2025. We illustrate our findings using numerical simulations.
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https://arxiv.org/abs/2507.22095
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Academic Papers
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db6ec0660df39243c76e95e8fc4ac4f53014afabc8c4be3011ba51d4c3565463
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2026-01-13T00:00:00-05:00
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Geometry-Controlled Freezing and Revival of Bell Nonlocality through Environmental Memory
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arXiv:2508.07046v2 Announce Type: replace-cross Abstract: We show that the distance between two qubits coupled to a structured reservoir acts as a single geometric control that can store, revive, or suppress Bell nonlocality. In a mirror-terminated guide, quantum correlations lost to the bath return at discrete recurrence times, turning a product state into a Bell-violating one without any entangling drive (only local basis rotations/readout). In the continuum limit, we derive closed-form criteria for the emergence of nonlocality from backflow, and introduce a Bell-based analogue of the BLP measure to quantify this effect. We also show how subwavelength displacements away from a decoherence-free node quadratically reduce the lifetime of a dark state or bright state, enabling highly sensitive interferometric detection. All results rely on analytically solvable models and are compatible with current superconducting and nanophotonic platforms, offering a practical route to passive, geometry-controlled non-Markovian devices.
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https://arxiv.org/abs/2508.07046
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0f42ddbb98e8f5c80f52181d9c783198e1bef2fcc734a1ccade3dcddd1c95b1d
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2026-01-13T00:00:00-05:00
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A Convergent Generalized Krylov Subspace Method for Compressed Sensing MRI Reconstruction with Gradient-Driven Denoisers
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arXiv:2508.11219v2 Announce Type: replace-cross Abstract: Model-based reconstruction plays a key role in compressed sensing (CS) MRI, as it incorporates effective image regularizers to improve the quality of reconstruction. The Plug-and-Play and Regularization-by-Denoising frameworks leverage advanced denoisers (e.g., convolutional neural network (CNN)-based denoisers) and have demonstrated strong empirical performance. However, their theoretical guarantees remain limited, as practical CNNs often violate key assumptions. In contrast, gradient-driven denoisers achieve competitive performance, and the required assumptions for theoretical analysis are easily satisfied. However, solving the associated optimization problem remains computationally demanding. To address this challenge, we propose a generalized Krylov subspace method (GKSM) to solve the optimization problem efficiently. Moreover, we also establish rigorous convergence guarantees for GKSM in nonconvex settings. Numerical experiments on CS MRI reconstruction with spiral and radial acquisitions validate both the computational efficiency of GKSM and the accuracy of the theoretical predictions. The proposed optimization method is applicable to any linear inverse problem.
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https://arxiv.org/abs/2508.11219
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689f7197c0d8f74c1c4ae5ed6d95b81c65a56108f93bf1d3cbf31f68e5aad3f6
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2026-01-13T00:00:00-05:00
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Gauge origami and quiver W-algebras IV: Pandharipande--Thomas $qq$-characters
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arXiv:2508.12125v2 Announce Type: replace-cross Abstract: We develop a contour integral formalism for computing the K-theoretic equivariant 3-vertex. Within the Jeffrey--Kirwan (JK) residue framework, we show that, by an appropriate choice of the reference vector, both the equivariant Donaldson--Thomas (DT) and Pandharipande--Thomas (PT) 3-vertices can be extracted from the same integrand. We analyze three distinct limits of the PT 3-vertex, recovering the unrefined topological vertex, the refined topological vertex, and the Macdonald refined topological vertex. Higher-rank extensions of PT counting and the DT/PT correspondence are also explored. From a quantum algebraic perspective, we construct an operator version of the equivariant PT 3-vertex and term it the Pandharipande--Thomas $qq$-character. We then discuss its connection with the quantum toroidal $\mathfrak{gl}_{1}$.
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https://arxiv.org/abs/2508.12125
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Academic Papers
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ff00b1c64c926c8d3dc670df13c194213047111040558fe643f0c9dfdae1840e
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2026-01-13T00:00:00-05:00
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Average weighted ratio of consecutive level spacings for infinite-dimensional orthogonal random matrices
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arXiv:2508.14172v2 Announce Type: replace-cross Abstract: The onset of quantum ergodicity is often quantified by the average ratio of consecutive level spacings. The reference values for ergodic quantum systems have been obtained numerically from the spectra of large but finite-dimensional random matrices. This work introduces a weighted ratio of consecutive level spacings, having the propery that the average can be computed numerically for random matrices of infinite dimension. A Painlev\'e differential equation is solved numerically in order to determine this average for infinite-dimensional orthogonal random matrices, thereby providing a reference value for ergodic quantum systems obeying time-reversal symmetry (provided that the time-reversal operator squares to the identity matrix). A Wigner surmise-inspired analytical calculation is found to yield a qualitatively accurate picture for the statistics of high-dimensional random matrices from each of the symmetry classes. For Poissonian level statistics, a significantly different average is found, indicating that the average weighted ratio of consecutive level spacings can be used as a probe for quantum ergodicity.
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https://arxiv.org/abs/2508.14172
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Academic Papers
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abea3fdbf7396f70c3d8a3924269efe36c90dc06f49855ff1ed27419d795afd8
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2026-01-13T00:00:00-05:00
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First Experimental Demonstration of Natural Hovering Extremum Seeking: A New Paradigm in Flapping Flight Physics
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arXiv:2508.20836v2 Announce Type: replace-cross Abstract: In this letter, we report the first experimental demonstration of the recently emerged new paradigm in flapping flight physics called (Natural Hovering Extremum Seeking (NH-ES)) [doi.org/10.1103/4dm4-kc4g], which theorized that hovering flight physics observed in nature by flapping insects and hummingbirds can be generated via a model-free, real-time, computationally basic, sensory-based feedback mechanism that only needs the built-in natural oscillations of the flapping wing as its propulsive input. We run experiments, including moth-like, light source-seeking, on a flapping-wing body in a total model-free setting that is agnostic to morphological parameters and body/aerodynamic models, and show that the flapping body gains altitude and stabilizes hovering about the light source autonomously needing only sensor measurements of light intensity.
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https://arxiv.org/abs/2508.20836
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38f8bf5b0661d09d82e2c041921730fead8283d1952079e265ab96d46af464a8
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2026-01-13T00:00:00-05:00
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A Kernel-based Stochastic Approximation Framework for Nonlinear Operator Learning
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arXiv:2509.11070v3 Announce Type: replace-cross Abstract: We develop a stochastic approximation framework for learning nonlinear operators between infinite-dimensional spaces utilizing general Mercer operator-valued kernels. Our framework encompasses two key classes: (i) compact kernels, which admit discrete spectral decompositions, and (ii) diagonal kernels of the form $K(x,x')=k(x,x')T$, where $k$ is a scalar-valued kernel and $T$ is a positive operator on the output space. This broad setting induces expressive vector-valued reproducing kernel Hilbert spaces (RKHSs) that generalize the classical $K=kI$ paradigm, thereby enabling rich structural modeling with rigorous theoretical guarantees. To address target operators lying outside the RKHS, we introduce vector-valued interpolation spaces to precisely quantify misspecification error. Within this framework, we establish dimension-free polynomial convergence rates, demonstrating that nonlinear operator learning can overcome the curse of dimensionality. The use of general operator-valued kernels further allows us to derive rates for intrinsically nonlinear operator learning, going beyond the linear-type behavior inherent in diagonal constructions of $K=kI$. Importantly, this framework accommodates a wide range of operator learning tasks, ranging from integral operators such as Fredholm operators to architectures based on encoder-decoder representations. Moreover, we validate its effectiveness through numerical experiments on the two-dimensional Navier-Stokes equations.
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https://arxiv.org/abs/2509.11070
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Academic Papers
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d8a8cab1b0a913c3d94bba13d81a90b2ba703d0e77c900da8e11d8b873f52a1b
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2026-01-13T00:00:00-05:00
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Predictive inference for time series: why is split conformal effective despite temporal dependence?
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arXiv:2510.02471v2 Announce Type: replace-cross Abstract: We consider the problem of uncertainty quantification for prediction in a time series: if we use past data to forecast the next time point, can we provide valid prediction intervals around our forecasts? To avoid placing distributional assumptions on the data, in recent years the conformal prediction method has been a popular approach for predictive inference, since it provides distribution-free coverage for any iid or exchangeable data distribution. However, in the time series setting, the strong empirical performance of conformal prediction methods is not well understood, since even short-range temporal dependence is a strong violation of the exchangeability assumption. Using predictors with "memory" -- i.e., predictors that utilize past observations, such as autoregressive models -- further exacerbates this problem. In this work, we examine the theoretical properties of split conformal prediction in the time series setting, including the case where predictors may have memory. Our results bound the loss of coverage of these methods in terms of a new "switch coefficient", measuring the extent to which temporal dependence within the time series creates violations of exchangeability. Our characterization of the coverage probability is sharp over the class of stationary, $\beta$-mixing processes. Along the way, we introduce tools that may prove useful in analyzing other predictive inference methods for dependent data.
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https://arxiv.org/abs/2510.02471
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f24040220b5ae3e8e5d99a90aa05fb0f074ea80a899c6fcf9b8f5b6b02fc98a9
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2026-01-13T00:00:00-05:00
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Quantum Filtering at Finite Temperature
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arXiv:2510.04967v2 Announce Type: replace-cross Abstract: We pose and solve the problem of quantum filtering based on continuous-in-time quadrature measurements (homodyning) for the case where the quantum process is in a thermal state. The standard construction of quantum filters involves the determination of the conditional expectation onto the von Neumann algebra generated by the measured observables with the non-demolition principle telling us to restrict the domain (the observables to be estimated) to the commutant of the algebra. The finite-temperature case, however, has additional structure: we use the Araki-Woods representation for the measured quadratures, but the Tomita-Takesaki theory tells us that there exists a separate, commuting representation and therefore the commutant will have a richer structure than encountered in the Fock vacuum case. We apply this to the question of quantum trajectories to the Davies-Fulling-Unruh model. Here, the two representations are interpreted as the fields in the right and left Rindler wedges.
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https://arxiv.org/abs/2510.04967
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Academic Papers
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2082771f33ddcd97499b3a41e4655cf40948fb9f7455bdbe70b7b66778d7ef5d
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2026-01-13T00:00:00-05:00
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Self-dual bivariate bicycle codes with transversal Clifford gates
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arXiv:2510.05211v2 Announce Type: replace-cross Abstract: Bivariate bicycle codes are promising candidates for high-threshold, low-overhead fault-tolerant quantum memories. Meanwhile, color codes are the most prominent self-dual CSS codes, supporting transversal Clifford gates that have been demonstrated experimentally. In this work, we combine these advantages and introduce a broad family of self-dual bivariate bicycle codes. These codes achieve higher encoding rates than surface and color codes while admitting transversal CNOT, Hadamard, and $S$ gates. In particular, we enumerate weight-8 self-dual bivariate bicycle codes with up to $n \leq 200$ physical qubits, realized on twisted tori that enhance code distance and improve stabilizer locality. Representative examples include codes with parameters $[[n,k,d]]$: $[[16,4,4]]$, $[[40,6,6]]$, $[[56,6,8]]$, $[[64,8,8]]$, $[[120,8,12]]$, $[[152,6,16]]$, and $[[160,8,16]]$.
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https://arxiv.org/abs/2510.05211
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Academic Papers
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a002d812dfae27fabdf8d926b00e830ab6d737fb1e8ac2b2cdc29e8f64dbf752
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2026-01-13T00:00:00-05:00
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A Universal Chern Model on Arbitrary Triangulations
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arXiv:2510.20862v2 Announce Type: replace-cross Abstract: Given a triangulation of a closed orientable surface, we place single-mode resonators or single-orbital artificial atoms at its vertices, edges and facets, and we devise near-neighbor hopping terms derived from the boundary and Poincar\'e duality maps of the simplicial complex of the triangulation. Regardless of the surface or its triangulation, these terms always lead to tight-binding Hamiltonians with large and clean topological spectral gaps, carrying non-trivial Chern numbers in the limit of infinite refinement of the triangulation. We confirm this via numerical simulations, and demonstrate how these models enable topological edge modes at the surfaces of real-world objects. Furthermore, we describe a metamaterial whose dynamics reproduces that of the proposed model, thus bringing the topological metamaterials closer to real-world applications.
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https://arxiv.org/abs/2510.20862
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Academic Papers
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ecbdb4e53a6ad0c43010bea961f217bbbad30eb20d9e2c8cdd6c837e7e5e81b0
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2026-01-13T00:00:00-05:00
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An Error-Based Safety Buffer for Safe Adaptive Control (Extended Version)
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arXiv:2510.23491v2 Announce Type: replace-cross Abstract: We consider the problem of adaptive control of a class of feedback linearizable plants with matched parametric uncertainties whose states are accessible, subject to state constraints, which often arise due to safety considerations. In this paper, we combine adaptation and control barrier functions into a real-time control architecture that guarantees stability, ensures control performance, and remains safe even with the parametric uncertainties. Two problems are considered, differing in the nature of the parametric uncertainties. In both cases, the control barrier function is assumed to have an arbitrary relative degree. In addition to guaranteeing stability, it is proved that both the control objective and safety objective are met with near-zero conservatism. No excitation conditions are imposed on the command signal. Simulation results demonstrate the non-conservatism of all of the theoretical developments.
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https://arxiv.org/abs/2510.23491
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Academic Papers
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a364d0d443b6feafcc332e5f265f91755b41dad5365c41217930808987be8ef1
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2026-01-13T00:00:00-05:00
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Gradient descent for deep equilibrium single-index models
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arXiv:2511.16976v2 Announce Type: replace-cross Abstract: Deep equilibrium models (DEQs) have recently emerged as a powerful paradigm for training infinitely deep weight-tied neural networks that achieve state of the art performance across many modern machine learning tasks. Despite their practical success, theoretically understanding the gradient descent dynamics for training DEQs remains an area of active research. In this work, we rigorously study the gradient descent dynamics for DEQs in the simple setting of linear models and single-index models, filling several gaps in the literature. We prove a conservation law for linear DEQs which implies that the parameters remain trapped on spheres during training and use this property to show that gradient flow remains well-conditioned for all time. We then prove linear convergence of gradient descent to a global minimizer for linear DEQs and deep equilibrium single-index models under appropriate initialization and with a sufficiently small step size. Finally, we validate our theoretical findings through experiments.
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https://arxiv.org/abs/2511.16976
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ac7ebc6a1726b770c93c0c5fddf4676b17d57439f3f32b1ffc16b5827077325a
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2026-01-13T00:00:00-05:00
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The Blueprints of Intelligence: A Functional-Topological Foundation for Perception and Representation
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arXiv:2512.05089v3 Announce Type: replace-cross Abstract: Real-world phenomena do not generate arbitrary variability: their signals concentrate on compact, low-variability subsets of functional space, enabling rapid generalization from few examples. A small child can recognize a dog after extremely limited exposure because the perceptual manifold of "dog" is compact, structured, and low-dimensional. We formalize this principle through a deterministic functional-topological framework in which the set of valid realizations produced by a physical process forms a compact subset of a Banach space, endowed with stable invariants, a finite Hausdorff radius, and an induced continuous perceptual functional. This geometry provides explicit limits on knowledge, conditions for identifiability, and guarantees for generalization from sparse evidence -- properties fundamental to both natural and artificial intelligence. Across electromechanical, electrochemical, and physiological domains, we show that real-world processes consistently generate compact perceptual manifolds with the same geometric characteristics. Their boundaries can be discovered in a fully self-supervised manner as the empirical radius saturates with increasing sampling, even when the governing equations are unknown. These results demonstrate that deterministic functional topology offers a unified mathematical foundation for perception, representation, and world-model construction. It provides a geometric explanation for why biological learners and self-supervised AI systems can generalize from few observations, and establishes compact perceptual manifolds as a fundamental building block for future AI architectures. Finally, this work unifies biological perception and modern self-supervised models under a single geometric principle: both derive their generalization ability from the compactness and invariants of real-world perceptual manifolds.
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https://arxiv.org/abs/2512.05089
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Academic Papers
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332faafde40d91e1be0278ebf9a4fa2d77843d701d6fd8fa3e489afe5b3cf924
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2026-01-13T00:00:00-05:00
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Low-Complexity Monitoring and Compensation of Transceiver IQ Imbalance by Multi-dimensional Architecture for Dual-Polarization 16 Quadrature Amplitude Modulation
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arXiv:2512.13266v2 Announce Type: replace-cross Abstract: In this paper, a low-complexity multi-dimensional architecture for IQ imbalance compensation is proposed, which reduces the effects of in-phase (I) and quadrature (Q) imbalance. The architecture use a transceiver IQ skew estimation structure to compensate for IQ skew, and then use a low-complexity MIMO equalizer to compensate for IQ amplitude/phase imbalance. In the transceiver IQ skew estimation structure, the receiver(RX) IQ skew is estimated by Gardner's phase detector, and the transmitter TX skew is estimated by finding the value that yields the lowest equalizer error. The low-complexity MIMO equalizer consists of a complex-valued MIMO (CV-MIMO) and a two-layer multimodulus algorithm real-valued MIMO (TMMA-RV-MIMO), which employ a butterfly and a non-butterfly structure, respectively. The CV-MIMO is used to perform polarization demultiplexing and the TMMA-RV-MIMO equalizes each of the two polarizations. In addition, the TMMA-RV-MIMO can recovery the carrier phase. A 100 km transmission simulation and experiment with 36 Gbaud dual-polarization 16 quadrature amplitude modulation (DP-16QAM) signals showed that, with the TX/RX IQ skew estimation, the estimation error is less than 0.9/0.25 ps. The low-complexity MIMO equalizer can tolerate 0.1 TX IQ amplitude imbalance and 5 degrees at a 0.3 dB Q-factor penalty. The number of real multiplications is reduced by 55% compared with conventional cases in total.
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https://arxiv.org/abs/2512.13266
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8746130b45f4cd0fcb9f1389a33fbae53b2184ab7d4fa2a16d9272f9b05aa895
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2026-01-13T00:00:00-05:00
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Modern Neuromorphic AI: From Intra-Token to Inter-Token Processing
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arXiv:2601.00245v3 Announce Type: replace-cross Abstract: The rapid growth of artificial intelligence (AI) has brought novel data processing and generative capabilities but also escalating energy requirements. This challenge motivates renewed interest in neuromorphic computing principles, which promise brain-like efficiency through discrete and sparse activations, recurrent dynamics, and non-linear feedback. In fact, modern AI architectures increasingly embody neuromorphic principles through heavily quantized activations, state-space dynamics, and sparse attention mechanisms. This paper elaborates on the connections between neuromorphic models, state-space models, and transformer architectures through the lens of the distinction between intra-token processing and inter-token processing. Most early work on neuromorphic AI was based on spiking neural networks (SNNs) for intra-token processing, i.e., for transformations involving multiple channels, or features, of the same vector input, such as the pixels of an image. In contrast, more recent research has explored how neuromorphic principles can be leveraged to design efficient inter-token processing methods, which selectively combine different information elements depending on their contextual relevance. Implementing associative memorization mechanisms, these approaches leverage state-space dynamics or sparse self-attention. Along with a systematic presentation of modern neuromorphic AI models through the lens of intra-token and inter-token processing, training methodologies for neuromorphic AI models are also reviewed. These range from surrogate gradients leveraging parallel convolutional processing to local learning rules based on reinforcement learning mechanisms.
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https://arxiv.org/abs/2601.00245
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Academic Papers
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2543033db0fb0811616f6689156057211416dccc02608e87a681088b0b25c563
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2026-01-13T00:00:00-05:00
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Improved Lower Bounds for Learning Quantum Channels in Diamond Distance
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arXiv:2601.04180v2 Announce Type: replace-cross Abstract: We prove that learning an unknown quantum channel with input dimension $d_A$, output dimension $d_B$, and Choi rank $r$ to diamond distance $\varepsilon$ requires $ \Omega\!\left( \frac{d_A d_B r}{\varepsilon \log(d_B r / \varepsilon)} \right)$ channel queries when $d_A\leq rd_B/2$ or $d_A=rd_B$. This improves the best previous $\Omega(d_A d_B r)$ bound by introducing explicit $\varepsilon$-dependence. We show that this scaling is optimal, up to logarithmic farctors, when $d_A=rd_B$. The proof constructs an ensemble of channels that are well separated in diamond norm yet admit Stinespring isometries that are close in operator norm.
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https://arxiv.org/abs/2601.04180
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179f83e797ea38e4fb4ba5ae189389f48a26a7ecad5ea19e53c5330c071196f3
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2026-01-13T00:00:00-05:00
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Exact Multimode Quantization of Superconducting Circuits via Boundary Admittance
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arXiv:2601.04407v2 Announce Type: replace-cross Abstract: We show that the Schur complement of the nodal admittance matrix, which reduces a multiport electromagnetic environment to the driving-point admittance $Y_{\mathrm{in}}(s)$ at the Josephson junction, naturally leads to an eigenvalue-dependent boundary condition determining the dressed mode spectrum. This identification provides a four-step quantization procedure: (i) compute or measure $Y_{\mathrm{in}}(s)$, (ii) solve the boundary condition $sY_{\mathrm{in}}(s) + 1/L_J = 0$ for dressed frequencies, (iii) synthesize an equivalent passive network, (iv) quantize with the full cosine nonlinearity retained. Within passive lumped-element circuit theory, we prove that junction participation decays as $O(\omega_n^{-1})$ at high frequencies when the junction port has finite shunt capacitance, ensuring ultraviolet convergence of perturbative sums without imposed cutoffs. The standard circuit QED parameters, coupling strength $g$, anharmonicity $\alpha$, and dispersive shift $\chi$, emerge as controlled limits with explicit validity conditions.
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https://arxiv.org/abs/2601.04407
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d9e048bbd39b25c1728e5637dbff5753ec2566c409bc98cf9f55005aa753769c
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2026-01-13T00:00:00-05:00
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Exoplanet characterization with NASA's Habitable Worlds Observatory
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arXiv:2601.06233v1 Announce Type: new Abstract: Exoplanet atmosphere characterization has seen revolutionary advances over the last few years, providing us with unique insights into atmospheric chemistry, dynamics and planet formation mechanisms. However, true solar system analog planets remain inaccessible. A major goal for exoplanet science over the coming decades is to observe, and characterize, temperate rocky planets and cool gas giants in orbit around solar-type stars, with the prospect of detecting signs of habitability or even life. Characterization and categorization of these planets relies on direct spectroscopic observations capable of identifying molecular species in their atmospheres; however, these observations represent a substantial engineering challenge due to the extreme contrast between a temperate, Earth-sized exoplanet and its parent star. NASA's next flagship mission, the Habitable Worlds Observatory (HWO) - planned for launch in the mid-2040s - will boast a coronagraphic instrument capable of reaching the needed 10$^{-10}$ contrast, on an ultrastable platform enabling long integration times to achieve the required signal to noise. HWO will cover near-ultraviolet to the near-infrared wavelengths, enabling detections of key biosignature molecules and habitability indicators such as ocean glint and a vegetation `red edge'. Via early involvement in this groundbreaking observatory, including a potential UK instrument contribution, the UK exoplanet community now has an important opportunity to influence the telescope's design. To maintain our international competitiveness, we must be at the forefront of observational campaigns with HWO when it eventually launches, and this comes with the need for parallel development in laboratory astrophysics and computational modelling. Maximising our exploitation of this transformative NASA mission requires consistent financial support in these areas across the next two decades.
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https://arxiv.org/abs/2601.06233
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42019fe0e682dfe8526617b6d599f3bcd853237d12197c15ab5d7e2224fb3003
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2026-01-13T00:00:00-05:00
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Transiting exoplanets as the immediate future for population-level atmospheric science
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arXiv:2601.06236v1 Announce Type: new Abstract: The transit method, during which a planet's presence is inferred by measuring the reduction in flux as it passes in front of its parent star, is a highly successful exoplanet detection and characterization technique. During transit, the small fraction of starlight that passes through a planet's atmosphere emerges with the fingerprints of atmospheric gases, aerosols and structure. During eclipse, the relatively small contribution of light from the planet itself may be observed as the planet is occulted by the star. For planets in near-edge-on, short-period orbits, observing the system throughout an entire orbit allows the varying flux from the planet to be extracted as the illuminated `dayside' rotates in and out of view. With spectroscopic observations, we can characterize not only the overall composition of the atmosphere, but also glean insights into atmospheric structure and dynamics. With over 6,000 transiting planets now discovered, such observations are currently our only window into a consistent sample of planetary atmospheres large enough to attempt a population-level study, a critical next step for our understanding of atmospheric science. The vast exoplanet population provides a laboratory for atmospheric physics, including chemistry, dynamics, cloud processes and evolution; extending these results to a larger number of targets will allow us to explore the effects of equilibrium temperature, gravity, mass and parent star type on atmospheric properties, as well as map observable trends to formation scenarios. These findings are critical for addressing STFC's Science Vision Challenge B: how do stars and planetary systems develop and how do they support the existence of life?. Here we outline how the UK must fit within this strategic context, suggest approaches and development for the future, and outline the unique capabilities and leadership of scientists across the UK.
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https://arxiv.org/abs/2601.06236
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ea85a34aed72fb286b737dbd9697b92fd9dd27c46d894e8935bcb8f8a4049d17
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2026-01-13T00:00:00-05:00
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Characterizing turbulence in galaxy clusters: defining turbulent energies and assessing multi-scale versus fixed-scale filters
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arXiv:2601.06250v1 Announce Type: new Abstract: Disentangling turbulence and bulk motions in the intracluster medium (ICM) of galaxy clusters is inherently ambiguous, as the plasma is continuously stirred by different processes on disparate scales. This poses a serious problem in the interpretation of both observations and numerical simulations. In this paper, we use filtering operators in real space to separate bulk motion from turbulence at different scales. We show how filters can be used to define consistent kinetic and magnetic energies for the bulk and turbulent component. We apply our GPU-accelerated filtering pipeline to a simulation of a major galaxy cluster merger, which is part of the PICO-Clusters suite of zoom-in cosmological simulations of massive clusters using the moving mesh code Arepo and the IllustrisTNG galaxy formation model. We find that during the merger the turbulent pressure fraction on physical scales $\lesssim$160 kpc reaches a maximum of 5%, before decreasing to 2% after $\sim$1.3 Gyr from the core passage. These low values are consistent with recent observations of clusters with XRISM, and suggest that unless a cluster was recently perturbed by a major merger, turbulence levels are low. We then re-examine the popular multiscale iterative filter method. In our tests, we find that its use can introduce artifacts, and that it does not reliably disentangle fluctuations living on widely separated length scales. Rather, we believe it is more fruitful to use fixed-scale filters and turbulent energies to compare between simulations and observations. This work significantly improves our understanding of turbulence generation by major mergers in galaxy clusters, which can be probed by XRISM and next-generation X-ray telescopes, allowing us to connect high-resolution cosmological simulations to observations.
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https://arxiv.org/abs/2601.06250
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e5bda963d12009ca2abec399115cc775768d4a1ad5f8e2cfe2541ab9b0abe59d
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2026-01-13T00:00:00-05:00
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Formation of massive multiple-star systems: early migration and mergers
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arXiv:2601.06251v1 Announce Type: new Abstract: Massive stars are often found in multiple systems, yet how binary-star systems with very close separations ($\lesssim$ au) assemble remains unresolved. We investigate the formation and inward migration of massive-star binaries in Solar-metallicity environments using the star-cluster formation simulation of Chon et al. (2024), which forms a $1200\,M_\odot$ stellar cluster and resolves binaries down to 1 au separation. Our results indicate that stars more massive than $2\,M_{\odot}$ predominantly assemble in binary or triple configurations, in agreement with observations, with member stars forming nearly coevally. In most of these systems, the inner binary hardens by one to three orders of magnitude and reaches a steady-state within the first $0.1\,$Myr. Notably, all binaries whose final separations are below 10 au are hardened with the aid of circumbinary discs, highlighting disc-driven migration as a key to produce tight massive binaries. We further find that binaries form with random inclinations relative to the initial rotation axis of the cloud, and that mutual inclinations in triple systems follow an isotropic distribution, implying that stochastic interactions driven by turbulence and few-body dynamics are crucial during assembly and migration. Finally, stars with $M>2\,M_{\odot}$ often undergo repeated merger events during cluster evolution, yielding extreme mass ratios ($q<0.1$). Some of these products may evolve into compact-object binaries containing a black hole or neutron star, including X-ray binaries and systems detectable by Gaia.
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https://arxiv.org/abs/2601.06251
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ef88e2c89cc35f5f4a52ef605ac77fdfe4a16a1012fbe7b8a01e3ea28e939d17
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2026-01-13T00:00:00-05:00
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Masers and Broad-Line Mapping Favor Magnetically-Dominated AGN Accretion Disks
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arXiv:2601.06253v1 Announce Type: new Abstract: We present a novel and powerful constraint on the physics of supermassive black hole (BH) accretion disks. We show that in the outer disk (radii $R \gtrsim 0.01\,$pc or $\gtrsim 1000\,R_{G}$), models supported by thermal or radiation pressure predict disk masses which are much larger than the BH mass and increase with radius - i.e. rapidly-rising, extremely non-Keplerian rotation curves. More generally, we show that any observational upper limit to the deviation from Keplerian potentials at these radii directly constrains the physical form of the pressure in disks. We then show that existing maser and broad line region (BLR) kinematic observations immediately rule out the classic thermal-pressure-dominated Shakura Sunyaev-like $\alpha$-disk model, and indeed rule out any thermal or radiation (or cosmic-ray) pressure-dominated disk, as the required temperatures and luminosities of the gas at large radii would exceed those observed by orders of magnitude. We show that models where the pressure comes entirely from turbulence (without thermal, radiation, or magnetic sources) could in principle be viable but would require turbulent Toomre $Q \gtrsim 100$, far larger than predicted by self gravitating/gravito-turbulent models. However, recently proposed models of magnetic pressure-dominated disks agree with all of the observational constraints. These magnetically-dominated models also appear to agree better with constraints on maser magnetic fields, compared to the other possibilities. Observations appear to strongly favor the hypothesis that the outer regions of BH accretion disks are in the 'hyper-magnetized' state.
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https://arxiv.org/abs/2601.06253
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b404f16b10be6329affe78bd7632e84ec55f81bd9584629d36038e410403fd5f
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2026-01-13T00:00:00-05:00
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GA-NIFS: high prevalence of dusty and metal-enriched outflows in massive and luminous star-forming galaxies at $z\sim3-9$
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arXiv:2601.06255v1 Announce Type: new Abstract: We present a search for and characterization of ionized outflows in 15 star-forming systems at $z\sim3-9$ with no evidence of Active Galactic Nuclei (AGN), observed with JWST/NIRSpec IFU as part of the GA-NIFS program. The targets often show satellites and complex substructure, from which we isolate 40 galaxies/regions. The sample probes the high-mass end of the galaxy population, with most sources having log$_{10}$~(M$_\star$/M$_\odot$)=$9.5-11$, extending previous studies on high-z star formation driven outflows that mainly focused on lower-mass galaxies. Using the [OIII]5007 and H$\alpha$ emission lines, we identify broad kinematic components consistent with galactic outflows in 14 galaxies/regions. We find that the outflowing gas is more dust attenuated (by $A_{\rm V}$$\sim0.59$ mag on average) and metal-enriched (0.13 dex) than the interstellar medium (ISM) of the host galaxies, but its velocities are insufficient to escape the galaxies and reach the circumgalactic medium, suggesting that outflows mainly redistribute dust and metals around their hosts. The outflows identified in this study display velocity dispersions within $\sigma_{\rm out}=130-340$~km~s$^{-1}$ and outflow velocities $v_{\rm out}=170-600$~km~s$^{-1}$, and, when combined with less luminous and less massive star-forming galaxies from previous works, reveal a statistically significant correlation between $v_{\rm out}$ and star formation rate (SFR). The typically low mass-loading factors ($\eta=\dot{M}_{\rm out}/SFR$$\leq1$, in 9 out of 14 the outflows) indicate that these outflows do not strongly suppress star formation. Overall, our results suggest that ejective feedback via ionized outflows is inefficient in massive, luminous star-forming galaxies within the first 2 Gyr of the Universe.
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https://arxiv.org/abs/2601.06255
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7775803e8968a3a7d73629f03864d081a20fa0dd4db57a58166911d21da35dfc
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2026-01-13T00:00:00-05:00
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Cosmological back-reaction of baryons on dark matter in the CAMELS simulations
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arXiv:2601.06258v1 Announce Type: new Abstract: Baryonic processes such as radiative cooling and feedback from massive stars and active galactic nuclei (AGN) directly redistribute baryons in the Universe but also indirectly redistribute dark matter due to changes in the gravitational potential. In this work, we investigate this "back-reaction" of baryons on dark matter using thousands of cosmological hydrodynamic simulations from the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project, including parameter variations in the SIMBA, IllustrisTNG, ASTRID, and Swift-EAGLE galaxy formation models. Matching haloes to corresponding N-body (dark matter-only) simulations, we find that virial masses decrease owing to the ejection of baryons by feedback. Relative to N-body simulations, halo profiles show an increased dark matter density in the center (due to radiative cooling) and a decrease in density farther out (due to feedback), with both effects being strongest in SIMBA (> 450% increase at r < 0.01 Rvir). The clustering of dark matter strongly responds to changes in baryonic physics, with dark matter power spectra in some simulations from each model showing as much as 20% suppression or increase in power at k ~ 10 h/Mpc relative to N-body simulations. We find that the dark matter back-reaction depends intrinsically on cosmology (Omega_m and sigma_8) at fixed baryonic physics, and varies strongly with the details of the feedback implementation. These results emphasize the need for marginalizing over uncertainties in baryonic physics to extract cosmological information from weak lensing surveys as well as their potential to constrain feedback models in galaxy evolution.
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https://arxiv.org/abs/2601.06258
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e69422c05c4cb47fb997c64f9ffb918f92d5c5afd9c9d864204f6617f9c09866
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2026-01-13T00:00:00-05:00
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Ultraviolet observations of atmospheric escape in exoplanets with the Habitable Worlds Observatory
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arXiv:2601.06263v1 Announce Type: new Abstract: Among the many recommendations of the Decadal Survey on Astronomy and Astrophysics 2020, we found that a priority area of research is to pave the pathways towards finding and characterizing habitable worlds. In this context, we aim to understand how planetary systems evolve through atmospheric escape, and develop techniques to identify potentially Earth-like worlds. Using the ultraviolet (UV) capabilities of the Habitable Worlds Observatory, we can use transit spectroscopy observations to determine what processes drive the evolution of exoplanets, how well can small exoplanets retain atmospheres, and search for Earth-like atmospheres. We advocate the development of a UV spectrograph that is capable of moderate- to high-resolution spectroscopy of point sources, access to key spectral features between 1000 and 3000 Angstrom, and UV detectors that are resilient to high count rates.
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https://arxiv.org/abs/2601.06263
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b3804984a7cddba382c451154c50578fbf9ff9fb6eb9c4de104d519cdded4d9b
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2026-01-13T00:00:00-05:00
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Spectral Signatures of Spinning Dust from Grain Ensembles in Diverse Environments: A Combined Theoretical and Observational Study
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arXiv:2601.06270v1 Announce Type: new Abstract: Recent observations of anomalous microwave emission (AME) reveal spectral features that are not readily reproduced by spinning dust models, motivating further investigation. We examine how dust grain distributions and environmental parameters determine the peak frequency and spectral width of AME spectral energy distribution (SED). Using Monte Carlo sampling and global sensitivity analysis, we find that AME features are dominantly controlled by three parameters: grain size, shape, and a phase-dependent environmental parameter. We also quantify the effects of SED broadening from ensembles of these dominant parameters, finding that the level of tension with observations is strongly phase dependent: Molecular Cloud (MC) is fully consistent, Dark Cloud (DC) shows minor deviations, and HII regions exhibit significant offsets in peak frequency. This points to possible issues in phase-dependent AME extraction, interstellar medium (ISM) environment identification, or underlying theoretical tension. Ensemble variations in both grain size and environmental parameters are required to reproduce the observed spread in peak frequency and spectral width. We further propose moment expansion and emulation-based inference methods for future AME spectral fit and feature analysis.
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https://arxiv.org/abs/2601.06270
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499504e4105fa16bac205140fa16cfdd76ae6b55dfeca88e6b921967af303d94
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2026-01-13T00:00:00-05:00
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The Energy-Duration Relationship in Astrophysical Self-Organized Criticality Systems
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arXiv:2601.06277v1 Announce Type: new Abstract: Scaling laws in astrophysical systems that involve the energy, the geometry, and the spatio-temporal evolution, provide the theoretical framework for physical models of energy dissipation processes. A leading model is the standard fractal-diffusive self-organized criticality (FD-SOC) model, which is built on four fundamental assumptions: (i) the dimensionality $d=3$, (ii) the fractal dimension $D_V=d-1/2=2.5$, (iii) classical diffusion $L \propto T^{(1/2)}$, and (iv) the proportionality of the dissipated energy to the fractal volume $E \propto V$. Based on these assumptions, the FD-SOC model predicts a scaling law of $T \propto E^k \propto E^{(4/5)} = E^{0.8}$. On the observational side, we find empirical scaling laws of $T \propto E^{0.81\pm0.03}$ by Peng et al.~(2023) and $T \propto E^{0.86\pm0.03}$ by Araujo \& Valio (2021) that are self-consistent with the theoretical prediction of the FD-SOC model. However, cases with a small time range $q_T = \log{(T_{max}/T_{min})} \lapprox 2$ have large statistical uncertainties and systematic errors, which produces smaller scaling law exponents ($k \approx 0.3, ..., 0.6$) as a consequence. The close correlation of the scaling exponent $k$ with the truncation bias $q_T$ implies that the dispersion of k-values is an observational effect, rather than a physical property.
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https://arxiv.org/abs/2601.06277
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7fd1e84652ff93ef6cb0837d3f3887da869023948afbf638d137fd8e1c734aa5
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2026-01-13T00:00:00-05:00
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VLBI Observations of SN 2012au Reveal a Compact Radio Source a Decade Post Explosion
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arXiv:2601.06278v1 Announce Type: new Abstract: Three leading models have been put forth to justify the observed radio re-brightening associated with stripped-envelope supernovae (SESNe) years post-explosion: radiation from an emerging pulsar wind nebula (PWN), shock interaction with a dense circumstellar medium (CSM), or emission from off-axis, relativistic jets. SN~2012au is a particularly intriguing SESN in this regard as observations obtained $\gtrsim$ 6 years post-explosion have shown \emph{both} (i) optical emission features consistent with a young PWN and (ii) a radio re-brightening. We present the results of our Very-Long-Baseline-Interferometric (VLBI) observations of SN 2012au performed between 8 to 13 years post core-collapse. Our VLBI observations reveal a luminous, steadily fading radio source that remains compact ($\leq1.4\times10^{17}~\mathrm{cm}$) and stationary ($\leq0.36c$) over the course of our campaign. Overall, we find that our VLBI measurements can be readily explained by a $\sim$decade-old PWN, potentially explained by shock interaction with specific CSM geometries, and are unlikely to be explained by emission from an off-axis, relativistic jet. Assuming a PWN origin, our observations require that the initial spin-down luminosity of the central pulsar be between $10^{36}~\mathrm{erg~s^{-1}}\leq\dot{E}_0\leq10^{42}~\mathrm{erg~s^{-1}}$ and radio efficiency factor be $\eta_\mathrm{R}\geq3\times10^{-6}$. These results are consistent with independent inferences obtained using optical spectroscopy of SN~2012au, alongside inferences of known Galactic systems. If a PWN origin is confirmed, SN 2012au would represent the first extragalactic PWN emerging from a modern day SN, providing a novel opportunity to study the formation properties of a decade-old pulsar.
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https://arxiv.org/abs/2601.06278
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58b164bd4d896e4ce56509d2cc2e0ec4bf23f8c8acfa744b83431e5911e1cd87
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2026-01-13T00:00:00-05:00
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CAMELS Environments: The Impact of Local Neighbours on Galaxy Evolution across the SIMBA, IllustrisTNG, ASTRID, and Swift-EAGLE Simulations
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arXiv:2601.06290v1 Announce Type: new Abstract: Internal feedback from massive stars and active galactic nuclei (AGN) play a key role in galaxy evolution, but external environmental effects can also strongly influence galaxies. We investigate the impact of environment on galaxy evolution, and its dependence on baryonic physics implementation, using Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) spanning a wide range of stellar and AGN feedback implementations in the SIMBA, IllustrisTNG, ASTRID, and Swift-EAGLE galaxy formation models. We show that satellite galaxies are significantly affected by the environment in all simulation models, with their gas fraction and star formation rate (SFR) suppressed in overdense regions compared to similar mass satellites in underdense environments at $z=0$. Central galaxies are less sensitive to environment but tend to show lower gas fraction and SFR in overdense regions at low stellar mass, transitioning to higher gas fraction and SFR for massive galaxies in higher-density environments. Halo baryon fraction ($f_{\rm B}$) and circumgalactic medium mass fraction ($f_{\rm CGM}$) at $z=0$ show clear environmental effects. In SIMBA, low-mass haloes in overdense regions have systematically lower $f_{\rm B}$ and $f_{\rm CGM}$ at fixed halo mass, while Swift-EAGLE haloes in overdense regions have systematically higher $f_{\rm B}$ and $f_{\rm CGM}$ across the full halo mass range, and IllustrisTNG and ASTRID show opposite trends at the low and high mass ends. Environmental effects can flip at higher redshift, with SFR and $f_{\rm B}$ increasing with local density in low-mass haloes before quenching at an increasing overdensity threshold. Our results demonstrate that the impact of environment on galaxy evolution depends significantly on galaxy formation model, and higher-density environments can either suppress or enhance star formation depending on galaxy mass and cosmic epoch.
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https://arxiv.org/abs/2601.06290
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206aba6cac77da8c2760afc1ff3ac546b5970b9b8202ccd6abc2062af0b73b13
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2026-01-13T00:00:00-05:00
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Star formation quenching precedes morphological transformation in COSMOS-WEB's richest galaxy groups
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arXiv:2601.06297v1 Announce Type: new Abstract: We analyzed the 25 richest galaxy groups in COSMOS-Web at z = 0.18-3.65, identified via the AMICO algorithm. These groups contain 20-30 galaxies with high (>75%) membership probability. Our study reveals both passive-density and active-density relations: late-type galaxies (LTGs) prefer higher central overdensities than early-type galaxies (ETGs) across all groups, and many massive LTGs exhibit colors typical of quiescent galaxies. We identify red sequences (RS) in 5 groups, prominently established at z < 1, with early emergence in the RS locus up to z ~ 2.2. This suggests group environments represent a transitional phase where star formation quenching precedes morphological transformation, contrasting with the classical morphology-density relation in rich clusters. In the central regions (~33 arcsec / 100 kpc from centers), we identified 86 galaxies: 23 (~27%) ETGs and 63 (~73%) LTGs. High-mass galaxies (M_star > 10^10.5 M_sun) undergo rapid quenching over ~1 Gyr, becoming predominantly spheroidal ETGs. This indicates morphological transformation accelerates in massive systems during peak cosmic star formation. Intermediate-mass galaxies (10^9 < M_star/M_sun < 10^10.5) show mild quenching, while low-mass galaxies (M_star < 10^9 M_sun) remain largely star-forming; here, environmental processes suppress star formation without destroying disks, suggesting group quenching operates on longer timescales than mass quenching. Overall, mass-dependent quenching dominates the high-mass end, while environment shapes lower-mass systems. The HLAGN fraction for both groups and field increases with redshift, peaking at z ~ 2, with groups consistently showing higher fractions. We suggest AGN feedback partially drives rapid quenching in high-mass galaxies, while mergers may trigger AGN activity.
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https://arxiv.org/abs/2601.06297
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4285804f4748521263dd470d152ef970b5ce9f928193846b8308f1ed418f8e91
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2026-01-13T00:00:00-05:00
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The Role of Interferometric Phase in Measuring Black Hole Photon Rings
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arXiv:2601.06313v1 Announce Type: new Abstract: The Event Horizon Telescope (EHT) captured the first images of a black hole using Very Long Baseline Interferometry (VLBI). In the near future, extensions of the EHT such as the Black Hole Explorer (BHEX) will allow access to finer-scale features, such as a black hole's ''photon ring.'' In the Kerr spacetime, this image structure arises from strong gravitational lensing near the black hole that results in a series of increasingly demagnified images of each emitting region that exponentially converge to a limiting critical curve. Exotic black hole alternatives, such as wormholes, can introduce additional photon rings. Hence, precisely characterizing multi-ring images is a promising pathway for measuring black hole parameters, such as spin, as well as exploring non-Kerr spacetimes. Here, we examine the interferometric response of multi-ring systems using a series of 1) simple geometric toy models, 2) synthetic BHEX and EHT observations of geometric models, and 3) semi-analytic accretion models with ray-tracing in the Kerr spacetime. We find that interferometric amplitude is more sensitive to the shape of the photon ring, while interferometric phase is more sensitive to its displacement, which is most sensitive to black hole spin. We find that for models similar to Messier 87* (M87*), the relative displacement of the first strongly lensed image from the weakly lensed direct image is approximately $1\,\mu {\rm as}$ per unit dimensionless spin, yielding an expected phase signature on a 25 G$\lambda$ baseline of $\sim44^\circ$ per unit spin.
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https://arxiv.org/abs/2601.06313
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d8646a703a1a256075fd6ad561d14d16ff2b90310d65f451dbfb148ca317ca82
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2026-01-13T00:00:00-05:00
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Incorporating Wavefront Error, Wavefront Sensing and Control, and Sensitivities into Exposure Time Calculations for Future Space Missions with the Error Budget Software (EBS)
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arXiv:2601.06342v1 Announce Type: new Abstract: A primary goal of NASA's Habitable Worlds Observatory (HWO) mission concept is to explore the Habitable Zones (HZ) of ~100 stellar systems and acquire spectra of ~25 terrestrial-type planets (with planet/star flux ratios on the order of 1E-10) which places tight constraints on the performance of observatory systems. In particular, coronagraph instrumentation needs to be matured for higher throughput, deeper contrasts, and better broadband performance, while also considering their sensitivity and ability to mitigate the impact of telescope instability and wavefront error (WFE), which can have a profound impact on exo-Earth imaging. The success of various proposed HWO mission architectures is often represented by the estimated exo-Earth candidate yield. Computation of the minimum exposure time to achieve the required signal-to-noise on a given target, using an exposure time calculator (ETC), is a key part of yield estimation. The impacts of coronagraph sensitivity, WFE, and wavefront sensing and control (WFS&C) have been well studied in the context of developing error budgets for missions and instruments such as the Roman Coronagraph Instrument, but there is currently no easily accessible way to incorporate the effects of these key parameters into calculating exposure times for HWO. To address this, we developed the Error Budget Software (EBS) - an open-source tool that synthesizes sensitivity, WFE, and WFS&C information for a variety of temporal and spatial scales and directly interfaces with the open-source yield code EXOSIMS to produce exposure times. We demonstrate how EBS can be used for mission error budgeting using the example of the Ultrastable Observatory Roadmap Team (USORT) observatory design. This includes both single and multi-variate parameter explorations using EBS where we identify trends between raw contrast and wavefront error, and detector noise and energy resolution.
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https://arxiv.org/abs/2601.06342
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af86b1a486338eead1c83676437284ade2f82396026293e55a3cabae3dade2f0
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2026-01-13T00:00:00-05:00
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Collision between molecular clouds IV: The role of feedback and magnetic field in head on collisions
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arXiv:2601.06355v1 Announce Type: new Abstract: We systematically investigate how cloud-cloud collisions influence star formation, emphasizing the roles of collision velocity, magnetic field orientation, and radiative feedback. Using the first cloud-cloud collision simulations that model individual star formation and accretion with all stellar feedback mechanisms, we explore the morphological evolution, star formation efficiency (SFE), fragmentation, stellar mass distribution, and feedback-driven gas dispersal. Our results show that cloud collisions substantially enhance the rate and timing of star formation compared to isolated scenarios, though the final SFE remains broadly similar across all setups. Lower collision velocities facilitate prolonged gravitational interaction and accumulation of gas, promoting sustained star formation characterized by elongated filamentary structures. Conversely, high-velocity collisions induce rapid gas compression and turbulent motions, leading to intense but transient episodes of star formation, which are curtailed by feedback-driven dispersal. The orientation of the magnetic field markedly affects collision outcomes. Parallel fields allow gas to collapse efficiently along magnetic lines, forming fewer but more massive stars. In contrast, perpendicular fields generate significant magnetic pressure, which stabilizes the shock-compressed gas and delays gravitational collapse, resulting in more distributed and less massive stellar fragments. Radiative feedback from massive stars consistently regulates star formation, halting further gas accretion at moderate efficiencies (10-15%) and initiating feedback-driven dispersal. Although the cloud dynamics vary significantly, the stellar mass function remains robust across scenarios-shaped modestly by magnetic orientation but only weakly influenced by collision velocity.
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https://arxiv.org/abs/2601.06355
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1ec2bc8697dac4a9f7c349e7ca26c97abc3faa3f71d70c4f50d2eb3690ae4fe0
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2026-01-13T00:00:00-05:00
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Exploring the internal structure of a neutron star and the associated magnetic fields aided by the mass-radius relationship
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arXiv:2601.06380v1 Announce Type: new Abstract: Neutron stars exhibit magnetic fields and densities far beyond those achievable in terrestrial laboratories, offering a natural probe of strongly interacting matter under extreme conditions. Using observationally anchored mass-radius relations and a density profile consistent with established equations of state, we construct a piecewise model that explicitly integrates the neutron-drip line, nuclear-saturation, the electron-dominated halo, and core-crust interfaces. The resulting structure reproduces the stiffness and curvature behavior across the nuclear-pasta regime reported in the literature, validating our treatment of the crust-core transition. From this model, we derive updated moments of inertia, crustal mass fractions, and the effective number of neutrons contributing to the star's magnetic moment. Comparing these quantities with spin-down inferred magnetic dipole moments indicates that the observed magnetic fields of particularly millisecond pulsars can be sustained entirely by the crustal neutron polarization, requiring alignment of only about $\lesssim5.5\%$ ($99\%$ C.L.) of the neutrons in the crust. This finding supports a crust-confined magnetic-field origin for non-magnetar neutron stars, consistent with magneto-thermal evolution studies, and provides a quantitative framework for connecting neutron-star observables to its underlying structure.
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https://arxiv.org/abs/2601.06380
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614f2580cb1753a9c6458ff4dbc805659b077c922df1469990cfbb0525298d5a
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2026-01-13T00:00:00-05:00
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NASA Decadal Astrobiology Research and Exploration Strategy (NASA-DARES 2025) White Paper -- Habitable Worlds Observatory Living Worlds Science Cases: Research Gaps and Needs
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arXiv:2601.06386v1 Announce Type: new Abstract: Executive Summary: The Habitable Worlds Observatory (HWO) is the first astrophysics flagship mission with a key cross-divisional astrobiology science goal of searching for signs of life on rocky planets beyond our solar system. The Living Worlds Working Group under the Science, Technology, and Architecture Review Team (START) was charged with investigating how HWO could characterize potentially habitable exoplanets orbiting stars in the solar neighborhood, search for signs of life, and interpret potential biosignatures within a false positive and false negative framework. In particular, we focused on (1) identifying biosignatures that have spectral features in the UV-Vis-NIR wavelength range and defining their measurement requirements, (2) determining additional information needed from the planet and planet system to interpret biosignatures and assess the likelihood of false positives, and (3) assembling current knowledge of likely HWO target stars and identify which properties of host stars and systems are most critical to know in advance of HWO. The Living Worlds atmospheric biosignatures science case is considered one of the key drivers in the design of the observatory. An additional 10 astrobiology science cases were developed that collectively revealed key research gaps and needs required to fully explore the observatory parameter space and perform science return analyses. Investment in these research gaps will require coordination across the Science Mission Directorate and fall under the purview of the new Division-spanning astrobiology strategy.
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https://arxiv.org/abs/2601.06386
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8e32bbbb9aefa5dee04de4eb8dce624f2e85e70f1aea16b44632e77c182c8767
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2026-01-13T00:00:00-05:00
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Generalized Bondi Accretion Flow with and without Outflow
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arXiv:2601.06397v1 Announce Type: new Abstract: The properties of accretion flows are affected by the angular momentum of the accreting gas. M.-G. Park found that the mass accretion rate, specifically, decreases significantly as the gas angular momentum increases. However, R. Narayan & A. C. Fabian found the decrease modest. We investigate global solutions for rotating polytropic flows in a much wider parameter space to understand their general properties within the slim disk approximation and a viscosity description suitable for both low- and high-angular-momentum flows. We find that the mass accretion rate for flows with a small Bondi radius decreases steeply as the gas angular momentum increases, while for those with a large Bondi radius, it decreases gradually. Therefore, the decrease of mass accretion rate due to gas rotation can be significant or mild depending on the Bondi radius. We further investigate global solutions of accretion with outflows using the ADIOS model of R. D. Blandford & M. C. Begelman. Stronger outflows in general slightly increase the mass inflow rate at the outer boundary, but the actual mass accreted into the black hole decreases by orders of magnitude. Stronger outflows also weaken the dependence of the mass accretion rate on the gas angular momentum when the viscosity parameter {\alpha} is small. The intricate dependence of the mass inflow rate at the outer boundary and the mass accretion rate into the black hole on gas angular momentum will have interesting implications for the growth of black holes and their energy output.
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https://arxiv.org/abs/2601.06397
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8822994adeb0db9a923a3c4f2996bef0e08b600e616b44c549bc4c718032844f
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2026-01-13T00:00:00-05:00
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Radio Signatures of Cosmic-Ray Particle Showers in Deep In-Ice Antennas
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arXiv:2601.06409v1 Announce Type: new Abstract: To detect ultra-high-energy neutrinos, experiments such as ARA and RNO-G target the radio emission induced by these particles as they cascade in the ice, using deep in-ice antennas at the South Pole or in Greenland. In this context, it is essential to first characterize the in-ice radio signature from cosmic-ray-induced particle showers, which constitute a primary background for neutrino detection, and represent the fist in-situ detection of in-ice particle cascades with radio antennas. This characterization will help validate the detection principle and assist in calibration. To achieve this goal, we used FAERIE, the "Framework for the simulation of Air shower Emission of Radio for in-Ice Experiments", that combines CoREAS and GEANT4 to simulate the radio emission of cosmic ray showers deep in the ice. Using this tool, we analyze in-ice radio signatures of cosmic-ray showers, including polarization, timing, and radiation energy, as well as their dependence on shower parameters. These insights will facilitate the first cosmic-ray detections and improve cosmic-ray/neutrino discrimination.
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https://arxiv.org/abs/2601.06409
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505dd8d3c16ccaa4d811309859966b270b30d12a39994ff278fa3d4567f50c90
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2026-01-13T00:00:00-05:00
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In-ice Radio Signatures of Cosmic Ray Particle Cascades
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arXiv:2601.06417v1 Announce Type: new Abstract: To detect ultra-high-energy neutrinos, experiments such as the Askaryan Radio Array and the Radio Neutrino Observatory in Greenland target the radio emission induced by these particles as they cascade in the ice, using deep in-ice antennas at the South Pole or in Greenland. A crucial step toward this goal is the characterization of the in-ice radio emission from cosmic-ray-induced particle showers. These showers form a primary background for neutrino searches, but can also be used to validate the detection principle and provide calibration signals for in-ice radio detectors. In this work, we use the Monte-Carlo framework FAERIE to perform the first characterization of cosmic ray signals with simulations that incorporate both their in-air and in-ice emissions. We investigate cosmic ray signatures such as their radiation energy, timing, polarization and frequency spectrum and quantify how they depend on shower properties. These results provide key guidelines for cosmic-ray identification and cosmic-ray neutrino discrimination in future in-ice radio experiments.
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https://arxiv.org/abs/2601.06417
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f0bdc3734fd5bf1423fccaf3c0dc49a73803fea0294ff5629be50f28f7d5a616
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2026-01-13T00:00:00-05:00
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Radio Morphing: Fast computation of inclined air shower radio emission
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arXiv:2601.06418v1 Announce Type: new Abstract: The preparation of next-generation large-scale radio experiments requires running a fast and efficient number of simulations to explore multiple detector configurations over vast areas and develop novel methods for the reconstruction of air shower parameters. While Monte Carlo simulations are accurate and reliable tools, they are too computationally expensive to explore the full parameter space of these new detectors within a reasonable timescale. We introduce a new version of Radio Morphing, a semi-analytical tool designed to simulate the radio emission of any cosmic-ray induced air shower with zenith angle $\theta>60^{\circ}$, at any desired antenna position, from the simulation data of a few reference showers at given positions. We present the latest performances of Radio Morphing which now provides simulation of air shower radio signals with average relative differences on the peak amplitude below $17\%$ on raw traces, below $15\%$ with a $3\sigma$ trigger threshold, below $13\%$ in the $[50-200]\,\rm MHz$ band, and even below $\sim 10\%$ in the $[30-80]\,\rm MHz$ band. These results are combined with a computation time reduced by more than four orders of magnitude, compared to standard Monte Carlo simulations.
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https://arxiv.org/abs/2601.06418
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d653b69ac8d9c7943d11c57b8c2bb58b27f70ad02252db1d85d41af2c6681f71
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2026-01-13T00:00:00-05:00
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Simulations of Electron Beam Interactions in Brown Dwarf Atmospheres
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arXiv:2601.06420v1 Announce Type: new Abstract: Over two decades ago, the first detection of electron cyclotron maser instability (ECMI) radio emission from a brown dwarf confirmed the presence of aurorally precipitating electrons on these objects. This detection established that brown dwarfs can exhibit magnetic activity that is planetary and auroral, rather than stellar in nature. This discovery motivated ongoing observational searches for the corresponding optical, ultraviolet (UV), and infrared (IR) auroral emission expected based on solar system analogs. The continuing nondetection of such auroral emission indicates important differences exist between auroral processes on brown dwarfs and solar system planets. In this work, we implement a Monte Carlo simulation of monoenergetic electron beams interacting with brown dwarf atmospheres, as a step towards understanding the physics of brown dwarf auroral emission. We detail the algorithm and underlying assumptions, and validate against previously published Jovian results (Hiraki et al. 2008). Our results agree well with literature, with some discrepancy from our updated interaction cross sections. We demonstrate the applicability of our simulation across the range of surface gravities and effective temperatures of radio-emitting brown dwarfs. We present an analytic parameterization of interaction rates based on our finding that atmospheric column density governs the interaction profiles. We apply this parameterization to calculate the total volumetric interaction rates and energy deposition rate for representative electron beam energy spectra enabling future predictions for spectra of aurorally emitting brown dwarfs. Simulations of high energy electron interactions with substellar hydrogen-dominated atmospheres will guide observational searches for multi-wavelength auroral features beyond the solar system.
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https://arxiv.org/abs/2601.06420
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b98c0031c431e91bf1a6a09f93c0e44658e28853c9ab4a59e1ded41ed7c0db7f
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2026-01-13T00:00:00-05:00
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Brahe: A Modern Astrodynamics Library for Research and Engineering Applications
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arXiv:2601.06452v1 Announce Type: new Abstract: Brahe is a modern satellite dynamics library for research and engineering applications. The representation and prediction of satellite motion is the fundamental problem of astrodynamics. Current research and applications in space situational awareness, satellite task planning, and space mission operations require accurate and efficient numerical tools to perform coordinate transformations, model perturbations, and propagate orbits. While the core algorithms for predicting and modeling satellite motion have been known for decades, there is a lack of modern, open-source software that implements these algorithms in a way that is accessible to researchers and engineers. brahe is designed to address these challenges by providing a modern, open-source astrodynamics library that is quick-to-deploy, composable, extensible, and easy-to-learn.
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https://arxiv.org/abs/2601.06452
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cf0b9042c4fb9fdf9b3de57ca221bbbdd3bf75d087fbdf0a0fecdffaab11b4e1
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2026-01-13T00:00:00-05:00
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Ruling Out Compact Jets as the Dominant Source of Radio Emission in Radio-quiet, High Eddington-ratio Active Galactic Nuclei
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arXiv:2601.06480v1 Announce Type: new Abstract: The origin of core radio emission in radio-quiet active galactic nuclei (AGNs) is still actively debated. General relativistic magnetohydrodynamics simulations often predict the launching of moderately large-scale jets from super-Eddington accretion flows, but this prediction seems at odds with observations indicating most high/super-Eddington AGNs appear radio quiet. Here, we use the ratio of radio to X-ray luminosities as a multiwavelength diagnostic to probe the origin of radio emission in a sample of 69 radio-quiet, high/super-Eddington AGNs with black-hole masses $M_{\rm BH} \sim 10^{5}-10^{9}~M_\odot$. With this wide dynamic range in $M_{\rm BH}$, we adapt existing formalisms for how jetted radio emission and accretion-powered X-ray emission scale with black hole mass into the super-Eddington regime. We find that the radio/X-ray luminosity ratios observed across this $M_{\rm BH}$ range are inconsistent with a jet-dominated model for radio emission. We discuss how our results may instead be consistent with a corona-dominated radio emission origin with a contribution from outflows at higher accretion rates.
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https://arxiv.org/abs/2601.06480
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22a51e802c080ebd5d037c427eb7ba2195a077121f1350a3af182a2d2124b07a
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2026-01-13T00:00:00-05:00
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High-order expansions of multi-revolution elliptic Halo orbits in the elliptic restricted three-body problem
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arXiv:2601.06563v1 Announce Type: new Abstract: Multi-revolution elliptic Halo (ME-Halo) orbits are a special class of symmetric and periodic solutions within the framework of the elliptic restricted three-body problem (ERTBP). During a single period, an M:N ME-Halo orbit completes $M$ revolutions around a libration point and the primaries revolve N times around each other. Owing to the repeated configurations, ME-Halo orbits hold great promise as nominal trajectories for space mission design. However, a major challenge associated with ME-Halo orbits lies in their mathematical description. To this end, we propose a novel method to derive high-order analytical expansions of ME-Halo orbits in the ERTBP by introducing two correction terms into the equations of motion in the y- and z-directions. Specifically, both the coordinate variables and correction terms are expanded as power series in terms of the primary eccentricity, the in-plane amplitude, and the out-of-plane amplitude. High-order approximations are constructed using a perturbation method, and their accuracy is validated through numerical analysis. Due to the inherent symmetry, ME-Halo orbits can be classified into four distinct families: southern/northern and periapsis/apoapsis groups. The analytical approximations developed in this study not only provide high-accuracy initial guesses for the numerical computation of ME-Halo orbits, but also offer new insights into the dynamical environment near collinear libration points in the ERTBP, thereby advancing practical applications in mission design.
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https://arxiv.org/abs/2601.06563
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0482cadff7d60edaecbe3c1654e0b9b3b7951018ea8b9b6d70bd7fb3f16da5bd
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2026-01-13T00:00:00-05:00
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A binary merger product as the direct progenitor of a Type II-P supernova
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arXiv:2601.06577v1 Announce Type: new Abstract: Type II-P supernovae (SNe II-P) are the most common class of core-collapse SNe in the local Universe and play critical roles in many aspects of astrophysics. Since decades ago theorists have predicted that SNe II-P may originate not only from single stars but also from interacting binaries. While ~20 SNII-P progenitors have been directly detected on pre-explosion images, observational evidence still remains scarce for this speculated binary progenitor channel. In this work, we report the discovery of a red supergiant progenitor for the Type II-P SN 2018gj. While the progenitor resembles those of other SNe II-P in terms of effective temperature and luminosity, it is located in a very old environment and SN 2018gj has an abnormally short plateau in the light curve. With state-of-the-art binary evolution simulations, we find these characteristics can only be explained if the progenitor of SN 2018gj is the merger product of a close binary system, which developed a different interior structure and evolved over a longer timescale compared with single-star evolution. This work provides the first compelling evidence for the long-sought binary progenitor channel toward SNe II-P, and our methodology serves as an innovative and pragmatic tool to motivate further investigations into this previously hidden population of SNe II-P from binaries.
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https://arxiv.org/abs/2601.06577
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04c2a3e38db3b2f1ae0eb9fbc98ca08efeae0256dbda2fef30127c027a3aeb44
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2026-01-13T00:00:00-05:00
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AstroSat UV Deep Field IV. An Extended UV disk around a massive spiral galaxy at z=0.67
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arXiv:2601.06581v1 Announce Type: new Abstract: Extended ultraviolet (XUV) emission in nearby disk galaxies supports the inside-out growth scenario through low-efficiency star formation in their outer regions. However, such detections have largely been limited to the local Universe (z ~ 0) due to the need for deep, high-resolution UV imaging. We report the detection of a clumpy XUV disk in a massive, isolated spiral galaxy $(log(M_*/M_\odot) \approx 11.04)$ at z=0.67, observed with AstroSat/UVIT. The intrinsic rest frame FUV surface brightness profile, corrected for the instrument PSF, shows a more extended disk than its optical and IR counterparts. The XUV disk reaches nearly twice the optical radius and includes a large UV-bright low surface brightness (LSB) region $(S_{LSB}/S_{K80}\approx9.3, \mu_{FUV}-\mu_K\approx 1)$, consistent with the Type II XUV definition. Additionally, the detection of UV clumps without optical counterparts supports a Type I classification, suggesting gravitational instabilities and recent star formation. These features point to recent cold gas accretion onto the outer disk. From the asymmetric light profile, we estimate a gas accretion rate of $\sim 11 M_\odot$ $yr^{-1}$, providing evidence of active disk growth at intermediate redshift.
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https://arxiv.org/abs/2601.06581
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11d39fad7991f8ae5126c3e5323e8b35e9e919d555c904e94b6f56e6e7b31244
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2026-01-13T00:00:00-05:00
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Constraining Inflation Models with Spinning Voids
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arXiv:2601.06589v1 Announce Type: new Abstract: We present a powerful new diagnostics by which the running of scalar spectral index of primordial density fluctuations can be tightly and independently constrained. This new diagnostics utilizes coherent rotation of void galaxies, which can be observed as redshift asymmetry in opposite sides dichotomized by the projected spin axes of hosting voids. Comparing the numerical results from the AbacusSummit of cosmological simulations, we derive a non-parametric model for the redshift asymmetry distribution of void galaxies, which turns out to be almost universally valid for a very broad range of cosmologies including dynamic dark energy models with time-dependent equation of states as well as the $\Lambda$CDM models with various initial conditions. We discover that the universality of this model breaks down only if the running of scalar spectral index deviates from zero, detecting a consistent trend that a more positive (negative) running yields a lower (higher) redshift asymmetry of voids than the model predictions. Given that non-standard inflations usually predict non-zero runnings of the spectral index and that the redshift asymmetry distribution of voids is a readily observable quantity, we conclude that this new diagnostics will pave another path toward understanding the true mechanism of inflation.
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https://arxiv.org/abs/2601.06589
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132ec50ed3e44b5f29f924763b93cb425a9ebd9a0f7e511100f1e61629e97f49
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2026-01-13T00:00:00-05:00
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Impact of a negative cosmological constant on the reconstruction of dark energy in light of DESI BAO data
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arXiv:2601.06656v1 Announce Type: new Abstract: An anti-de Sitter vacuum, corresponding to a negative cosmological constant (NCC), might coexist with one evolving positive dark energy component at low redshift and is hinted by the latest DESI observations. In this paper, we use two methods, \textit{redshift-binned} and \textit{Gaussian Process-based} reconstructions to investigate the effect of a NCC on the equation of state (EOS) $w(z)$ of evolving dark energy (DE) component. We find that a NCC is slightly preferred in both the two reconstructions by up to $\simeq1\sigma$. Although the degeneracy between the EOS of evolving DE component and NCC weakens the constraint on the reconstructed $w(z)$, this degeneracy leads to the phantom divide $w=-1$ more consistent with the 1$\sigma$ posterior of $w(z)$.
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https://arxiv.org/abs/2601.06656
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b4aed8ee477198e49178ca76b586b5514ef6eea789ad6e371f6e2d22c4c6528a
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2026-01-13T00:00:00-05:00
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Evaluating the efficacy of a data cube treatment procedure for kinematic analyses: application to NGC 3115 and NGC 4699
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arXiv:2601.06718v1 Announce Type: new Abstract: Data cubes have been increasingly used in astronomy. These data sets, however, are usually affected by instrumental effects and high-frequency noise. In this work, we evaluate the efficacy of a data cube treatment methodology, previously proposed by our research group, for analyses focused on the stellar and gas kinematics. To do that, we used data cubes of the central regions of the galaxies NGC 3115 and NGC 4699, obtained with the Integral Field Unit of the Gemini Multi-Object Spectrograph. For each galaxy, we analysed three data cubes: non-treated, filtered (with the Butterworth spatial filtering) and filtered and deconvolved (with the Richardson-Lucy deconvolution). For each data cube, we performed a dynamical modelling, using Jeans Anisotropic Models, to obtain, among other parameters, the masses of the central supermassive black holes. Both for NGC 3115 and NGC 4699, the values of the parameters provided by the dynamical modelling from the non-treated, filtered and filtered and deconvolved data cubes were compatible, at the 1-$\sigma$ level. However, the use of the Butterworth spatial filtering decreased the uncertainty of the parameters. The additional use of the Richardson-Lucy deconvolution decreased even more the uncertainty of the parameters. The complete data treatment procedure resulted in decreases of 41% and 45% in the uncertainties of the supermassive black hole masses in NGC 3115 and NGC 4699, respectively. These results indicate that our treatment procedure not only does not compromise analyses of data cubes focused on the stellar or gas kinematics, but actually improves the quality of the results.
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https://arxiv.org/abs/2601.06718
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9cd4d7f4a5f8d63fd97f38e5de09ba8201920f1aef2ac312a81e4eb9e2f1f447
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2026-01-13T00:00:00-05:00
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SPHEREx Re-Observation of Interstellar Object 3I/ATLAS in December 2025: Detection of Increased Post-Perihelion Activity, Refractory Coma Dust, and New Coma Gas Species
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arXiv:2601.06759v1 Announce Type: new Abstract: In December-2025, the NASA SPHEREx spacecraft re-observed ISO 3I/ATLAS post-perihelion, finding a much more active object compared to August-2025 SPHEREx pre-perihelion observations, with marked evidence for development into an cometary body fully sublimating all its ices. The new imaging spectrophotometry is dominated by spatially resolved features due to dust scattered-light and thermal emission plus gas-emissions from CN (0.93 um), H2O (2.7 um), organic C-H (3.2 to 3.6 um), CO2 (4.25 to 4.27 um), and CO (4.6 to 4.8 um). The CO2 gas-coma continues to be extended out to a 3 arcmin radius. The continuum spectral signature of H2O-ice absorption has mostly disappeared, replaced by scattered-light plus thermal-emission from organo-silicaceous dust grains while the H2O gas-emission is 20 times brighter. All but the organics-gas comae are circularly symmetric, while a weak pear-shaped solar-pointing dust tail consistent with large dust grains is now present. The new appearance of CN and C-H features suggests that these species are contained either in H2O phases or were trapped under them.
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https://arxiv.org/abs/2601.06759
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b930280082ae0c374d2f839743c9b217a14b944cd4f187191664fbaf33337df4
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2026-01-13T00:00:00-05:00
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Joint Optical-HI mock catalogs and prospects for upcoming HI surveys
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arXiv:2601.06815v1 Announce Type: new Abstract: Atomic hydrogen (HI) regulates star formation as cold gas fuels star formation. It represents a key phase of matter in the baryon cycle involving accretion, feedback, outflows, and gas recycling. Redshifted $21$ cm line emission originating from galaxies serves as a key tracer for investigating HI gas and its dynamics in the interstellar medium (ISM) and circumgalactic medium (CGM), and enables the study of galaxy evolution. Nonetheless, direct detections of HI are currently limited to $z \leq 0.4$ due to the inherently weak $21$ cm emission line. Ongoing and upcoming large radio surveys aim to detect $21$ cm emission from galaxies up to $z \gtrsim 1$ with unprecedented sensitivity. In current work, we present a novel approach for creating optical-HI joint mock catalogs for upcoming SKA precursor surveys: MIGHTEE-HI and LADUMA with MeerKAT and WALLABY with ASKAP. Incorporation of optical properties along with HI in our mock catalogs makes these a powerful tool for making predictions for upcoming surveys and provides a benchmark for exploring the HI science (e.g., conditional HIMF and optical-to-HI scaling relations) expected from these surveys. As a case study, we show the use of the joint catalogs for predicting the expected outcome of stacking detection for average HI mass in galaxies that are below the threshold for direct detection. We show that combining stacking observations with the number of direct detections puts a strong constraint on the HI mass function, especially in the regime where the number of direct detections is small, as often happens near the farther edge of HI surveys. This intermediate step may be used to set priors for the full determination of the HI mass function.
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https://arxiv.org/abs/2601.06815
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cf992a8dcc186e569cb297a0185926c42cdbfd827a68437fa1250609d073a9db
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2026-01-13T00:00:00-05:00
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Computing Natural Magnitudes in the Photometric Systems of Astronomical Plates using Gaia DR3 SEDs
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arXiv:2601.06859v1 Announce Type: new Abstract: Context. Accurate photometric calibration of astronomical photographic plates remains a fundamental challenge in astronomy, especially when bridging historical photographic data with modern observations due to the mismatch of spectral sensitivities of photographic plates and passbands of modern calibration catalogs. Aims. We intend to derive consistent natural magnitudes for celestial sources within the intrinsic photometric systems of astronomical photographic plates by using Gaia Data Release 3 (DR3) blue photometer (BP) and red photometer (RP) low-resolution spectral data and to show its superiority to former methods. Methods. We compiled spectral characteristic data for emulsions and filters applied in photometric observations using glass plates. The collected color sensitivities, modified by atmospheric reddening depending on the air mass, are then used to compute accurate natural magnitudes and fluxes of objects in the photographic plates through synthetic photometry, utilizing a catalog of Gaia spectral energy distributions (SEDs) over the wavelength range 330 nm to 1050 nm (XP spectra). This process uses GaiaXPy, a Python library designed to handle Gaia DR3 spectral data. These natural magnitudes are then compared with results from the color term method used to compile the data in existing photoplate archives. Results. Comparing the synthetic magnitudes with those existing in the Archives of Photographic PLates for Astronomical USE (APPLAUSE), we were able to reveal systematic errors of the existing data in the range of +/-0.3 mag and higher. In addition, the presented method allows for an accommodation of stars with similar color index but of different luminosity classes as well as an effective correction of atmospheric reddening at higher air masses, approximately 0.2 mag.
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https://arxiv.org/abs/2601.06859
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6610912156de4c12da0885ef4dfced8a783ad26f731361077a724820797d14a8
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2026-01-13T00:00:00-05:00
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Turbulent Properties of Interplanetary Coronal Mass Ejections Observed by Solar Orbiter in the Inner Heliosphere
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arXiv:2601.06904v1 Announce Type: new Abstract: We investigate the turbulent properties of 12 interplanetary coronal mass ejections (ICMEs) observed by Solar Orbiter between 0.29 and 1.0 AU. We analyze fluctuation power, spectral indices, break scales, and correlations between magnetic and velocity fluctuations (v-b) to quantify differences between ICME substructures (sheath and magnetic ejecta (ME)) and the surrounding solar wind. The ICME sheath is consistently the most turbulent region at all distances. In the solar wind, Alfv\'enicity influences inertial-range scaling, resulting in either single power laws near f^-3/2 or f^-5/3, or a coexistence of both, whereas ICME substructures consistently exhibit Kolmogorov-like f^-5/3 spectra. Alfv\'enicity is reduced within ICMEs, particularly in the ejecta, indicating more balanced Alfv\'enic fluctuations than in the solar wind. Spectral breaks shift to higher frequencies in ICME regions, with average break frequencies of 0.53 +/- 0.35 Hz (solar wind), 1.87 +/- 1.46 Hz (sheath), and 1.46 +/- 1.28 Hz (ME), reflecting differences in underlying microphysical scales. Our findings highlight distinct turbulence regimes in ICMEs compared to the solar wind and support the use of fluctuation power, spectral breaks, and v-b correlations as effective diagnostics for identifying ICME boundaries.
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https://arxiv.org/abs/2601.06904
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1440983b5565c8c57934cf72fcace42ab223d00cc5743376a2215f65920b3cf4
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2026-01-13T00:00:00-05:00
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The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies-VIII. A Census of Long-Period Variable Stars across the Andromeda Dwarf Satellite System
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arXiv:2601.06924v1 Announce Type: new Abstract: We present a comprehensive catalog, in the Sloan $i$ and Harris $V$ filters, of long-period variable (LPV) stars in the spheroidal dwarf satellites of the Andromeda galaxy, based on a dedicated survey for variable stars in Local Group dwarf systems. Using photometric time-series data obtained with the Wide Field Camera (WFC) on the 2.5 m Isaac Newton Telescope (INT), we identify approximately 2800 LPV candidates across 17 Andromeda satellites, spanning a broad range in luminosity and variability amplitude. This study is accompanied by a public data release that includes two comprehensive catalogs, a catalog of the complete stellar populations for each galaxy and a separate catalog listing all identified LPV candidates. Both are available through CDS/VizieR and provide a valuable resource for investigating quenching timescales, stellar mass distributions, and the effects of mass-loss and dust production in dwarf galaxies. We derive updated structural parameters, including newly measured half-light radii, and determine distance moduli using the Tip of the Red Giant Branch (TRGB) method with Sobel-filter edge detection, yielding values between $23.38\pm0.06$ and $25.35\pm0.06$ mag.
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https://arxiv.org/abs/2601.06924
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275e8028329bd23b3fcd69d46e97d89425f7896c56ef2b32c6aed37e79c0f879
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2026-01-13T00:00:00-05:00
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Nitrogen abundances in star-forming galaxies 2.2 Gyr after the Big Bang are not elevated
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arXiv:2601.06968v1 Announce Type: new Abstract: Using deep medium-resolution JWST rest-optical spectra of a sample of typical star-forming galaxies (Lyman break galaxies and Lyman-$\alpha$ emitters) from the LyC22 survey at $z \sim 3$, we determined the nebular abundances of N, O, and Ne relative to H for a subsample of 25 objects with the direct method, based on auroral [OIII]4363 line detections. Our measurements increases the number of accurate N/O determinations at $z \sim 2-4$ using a homogeneous approach. We found a mean value of $\log({\rm N/O})=-1.29^{+0.25}_{-0.21} $ over a metallicity range 12+log(O/H)=7.5 to 8.44. The observed N/O ratio and scatter are indistinguishable from that observed in low-z galaxies and HII regions over the same metallicity range, showing thus no redshift evolution of N/O for typical galaxies over a significant fraction of cosmic time. We also show that typical $z \sim 3$ galaxies show a similar offset in the BPT diagram as galaxies from the low-z Lyman Continuum Survey (LzLCS), when compared to the average of SDSS galaxies, and show that this offset is not due to enhanced nitrogen abundances. Our results establish a basis for future studies of the evolution of N and O at higher redshifts.
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https://arxiv.org/abs/2601.06968
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b27fe46783c4295d41a4894e45f406371548e199dd33826d6444e270f5640479
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2026-01-13T00:00:00-05:00
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Rings around irregular bodies. II. Numerical simulations of the 1/3 spin-orbit resonance confinement and applications to Chariklo
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arXiv:2601.06975v1 Announce Type: new Abstract: Rings have been found around Chariklo, Haumea and Quaoar, three small objects of the Solar System. All these rings are observed near the second-order spin-orbit resonances (SORs) 1/3 or 5/7 with the central body, suggesting an active confinement mechanism by these resonances. Our goal is to understand how collisional rings can be confined near second-order SORs in spite of the fact that they force self-intersecting streamlines.We use full 3D numerical simulations that treat rings of inelastically colliding particles orbiting non-axisymmetric central bodies, characterized by a dimensionless mass anomaly parameter mu. While most of our simulations ignore self-gravity, a few runs include gravitational interactions between particles, providing preliminary results on the effect of self-gravity on the ring confinement. The 1/3 SOR can confine ring material, by transferring the forced resonant mode into free Lindblad modes. We derive a criterion ensuring that the 1/3 SOR counteracts viscous spreading. Assuming meter-sized ring particles, and tau~1, this requires a threshold value mu > 1e-3 in Chariklo's case. The confinement is not permanent as a slow outward leakage of particles is observed in our simulations. This leakage can be halted by an outside moonlet with a mass of ~1e-7 - 1e-6 relative to Chariklo, corresponding to subkilometer-sized objects. With self-gravity, the ring viscosity nu increases by a factor of few in low-tau rings due to gravitational encounters. For large tau, self-gravity wakes enhance nu by a factor of ~100 compared to a non-gravitating ring, requiring ~10-fold larger mu since the threshold value increases proportional to square-root of nu.
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https://arxiv.org/abs/2601.06975
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6f2ae1ed0edc4fbf5e066a8ec96bb4d5c7b8594933b8e911c6dc5c97d464d89a
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2026-01-13T00:00:00-05:00
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Magnetic winds in resistive compact binary discs
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arXiv:2601.06994v1 Announce Type: new Abstract: Dwarf Novae and low-mass X-ray binaries are eruptive binary systems comprised of a Roche-lobe overflowing solar-type star and an accreting compact object. Their recurrence time can be explained by a low-accreting phase, the quiescence, during which the angular momentum transport parameter is inferred to be $\alpha \approx 0.01$ by the Disc Instability Model. Non-magnetics mechanisms, such as spiral wave transport, only achieve angular momentum transport an order of magnitude too low, at best, because these discs are so thin in quiescence. During this phase, the Magneto-rotational Instability is known to be suppressed by the increased resistivity of the weakly ionised plasma. Studying these thin magnetised discs is a numerical challenge because of the wide range of scales to be resolved. Thanks to the new GPU-accelerated code Idefix, we produce global 3D MHD simulations of a very thin disc $(H/R = 0.01)$ for the first time. We explore the possibility that an MHD wind arises and increases accretion in low magnetic Reynolds number $(\mathrm{Rm}\approx100)$ and realistic plasma parameter ($\beta \approx 1000$) regimes. We observe that the MRI is only quenched in the resistive disc bulk but survives in the disc atmosphere. This drives strong accretion and wind launching. We quantify the efficiency of the resulting wind and measure its global effect on the disc. We explore the effect of the initial disc magnetisation and compare the accretion/ejection regime with and without resistivity.
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https://arxiv.org/abs/2601.06994
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6ee9beb984e6bdf8f8e0ef2f4325c87fed97353c2af3f60185ee7337485ff042
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2026-01-13T00:00:00-05:00
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The Structure of Poloidal Fields Embedded in Thin Disks
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arXiv:2601.07031v1 Announce Type: new Abstract: Many accreting systems are modeled as geometrically thin disks. Simulations of accretion disks cannot be extended to this regime, although local models can address the behavior of narrow annuli. A global model needs to account for the interactions between a large-scale poloidal field, accreted from the environment, and the disk. The disk magnetosphere can be modeled subject to the boundary conditions imposed by the disk. These depend on the structure of the magnetic field as it crosses the disk and the degree to which the disk can support a bend in the field lines. Building on earlier work we derive a set of equations describing a stationary disk with an embedded poloidal field. We derive a modified induction equation that incorporates tensorial turbulent diffusivities and a helicity-regulated $\alpha$-effect. We quantify how helicity conservation introduces a nonlinear backreaction on the large-scale dynamo, dynamically coupling turbulent diffusion and $\alpha$-quenching. We discuss the challenges encountered in finding a unique solution under stationary flows $E_\phi =0$, which balances the inflow of $B_z$ due to accretion, the outflow due to radial diffusion of $B_z$, and the vertical movement of $B_r$ due to turbulent diffusion and buoyancy. The vertical profiles of both the azimuthal diffusion coefficient $D_{ijk}$ and the helicity-driven $\alpha_{ij}$ demonstrate that changes in the radial gradient can restructure the magnetic field geometry. The ability of disks to sustain large bending angles in the poloidal field implies that angular momentum flux through the magnetosphere can dominate over internal transport even for weak fields. Competing factors can result in non-unique solutions, necessitating extra constraints and diagnostics that highlight the role of isotropic turbulence and helicity regulation in magnetized disk environments.
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https://arxiv.org/abs/2601.07031
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6f4d61c58a8682ee35663e0f29067106d8af136e0f0a12d025b2c4b1455c871b
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2026-01-13T00:00:00-05:00
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A New Consistency Test for the $\Lambda$CDM Model using Radial and Transverse BAO Measurements
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arXiv:2601.07075v1 Announce Type: new Abstract: We present a calibration-free consistency test of spatially flat $\Lambda$CDM based on baryon acoustic oscillation (BAO) distance measurements. The method forms ratios of BAO distances -- the Hubble distance $\DH(z)$, the comoving angular diameter distance $\DM(z)$, and the volume-averaged distance $\DV(z)$ -- so that the sound horizon scale cancels, and then maps each observed ratio to an effective flat-$\Lambda$CDM matter density parameter, $\OmL$, defined as the value of $\Omega_{\rm M}$ that reproduces the measured ratio within $\Lambda$CDM. Flat $\Lambda$CDM predicts that $\OmL$ should be independent of redshift and of the particular ratio used. For ratios involving the integrated distances $\DM$ and $\DV$, we associate them with well-defined effective line-of-sight redshift intervals using a redshift-matching strategy based on the integral mean value theorem. We apply the test to BAO measurements from the Dark Energy Spectroscopic Instrument (DESI) Data Release~1 and Data Release~2, propagating the full published BAO covariance matrices into all derived ratios and $\OmL$ constraints. Within current uncertainties, the inferred $\OmL$ values are broadly consistent with a redshift-independent constant, providing an internal consistency check of flat $\Lambda$CDM that can be strengthened straightforwardly as BAO measurements improve.
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https://arxiv.org/abs/2601.07075
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dfd790428568f628c459fb68125b9259057f05ffa0fbcc37a4e9aaf6b5ccd681
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2026-01-13T00:00:00-05:00
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Magma Ocean Waves and Thermal Variability on Lava Worlds
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arXiv:2601.07080v1 Announce Type: new Abstract: Lava worlds are rocky planets with dayside skins made molten by stellar irradiation. Tidal heating on these shortest-period planets is more than skin deep. We show how orbital eccentricities of just a few percent (within current observed bounds and maintained secularly by exterior companions) can create deep magma oceans. ``Lava tidal waves'' slosh across these oceans; we compute the multi-modal response of the ocean to tidal forcing, subject to a coastline at the day-night terminator and a parameterized viscous drag. Wave interference produces a dayside heat map that is spatially irregular and highly time-variable; hotspots can wander both east and west of the substellar point, and thermal light curves can vary and spike aperiodically, from orbit to orbit and within an orbit. Heat deposited by tides is removed in steady state by a combination of fluid, mushy, and solid-state convection in the mantle. For Earth-sized planets with sub-day periods, the entire mantle may be tidally liquified.
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https://arxiv.org/abs/2601.07080
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81dd55220d506c514e0d6f798c9377d8054db8285109beebfb19a5e8b78430e3
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2026-01-13T00:00:00-05:00
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On the 3D time evolution of the dust size distribution in protostellar envelopes
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arXiv:2601.07088v1 Announce Type: new Abstract: Dust plays a fundamental role during protostellar collapse, disk and planet formation. Recent observations suggest that efficient dust growth may begin early, in the protostellar envelopes, potentially even before the formation of the disk. Three-dimensional models of protostellar evolution, addressing multi-size dust growth, gas and dust dynamics and magnetohydrodynamics, are required to characterize the dust evolution in the embedded stages of star formation. We aim to establish a new framework for dust evolution models, following in 3D the dust size distribution both in time and space, in MHD models describing the formation and evolution of star-disk systems, at low numerical cost. We present our work coupling the COALA dust evolution module into the code RAMSES, performing the first 3D MHD simulation of protostellar collapse including simultaneously polydisperse dust growth modeled by the Smoluchowski equation as well as dust dynamics in the terminal velocity approximation. Ice-coated micron-sized grains can rapidly grow in the envelope and survive by not entering the fragmentation regime. The evolution of the dust size distribution is highly anisotropic due to the turbulent nature of the collapse and the development of favorable locations such as outflow cavity walls, which enhance locally the dust-to-gas ratio. We analyzed the first 3D non-ideal MHD simulations that self-consistently account for the dust dynamics and growth during the protostellar stage. Very early in the lifetime of a young embedded protostar, micron-sized grains can grow, and locally the dust size distribution deviates significantly from the MRN initial shape. This new numerical method opens the perspective to treat simultaneously gas/dust dynamics and dust growth in 3D simulations at a low numerical cost for several astrophysical environments.
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https://arxiv.org/abs/2601.07088
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54300e4626e3ce9805ce0a0a1fb01f48ad25371213b96d78771c5612e319049b
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2026-01-13T00:00:00-05:00
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More power on large scales
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arXiv:2601.07106v1 Announce Type: new Abstract: The high value of the cosmic microwave dipole may be telling us that dark matter is macroscopic rather than a fundamental particle. The possible presence of a significant dark matter component in the form of primordial black holes suggests that dark halo formation simulations should be commenced well before redshift z = 100. Unlike standard CDM candidates, PBHs behave as dense, non-relativistic matter from their inception in the radiation-dominated era. This allows them to seed gravitational potential wells and begin clustering earlier. We find that starting N-body simulations at redshifts even before matter-radiation equality yield galaxy bulk flow velocities that are systematically larger than those predicted by standard LCDM models. The early, high-mass concentrations established by PBHs lead to a more rapid and efficient gravitational acceleration of surrounding baryonic and dark matter, generating larger peculiar velocities that remain coherent over scales of hundreds of Mpc. Furthermore, a sub- population of PBHs in the 10^-20 to 10^-17 solar mass range would lose a non-negligible fraction of their mass via Hawking radiation over cosmological timescales. This evaporation process converts matter into radiation, so a time-varying matter density parameter, Omega_m', is introduced, which behaves like a boosted radiation term in the Friedmann equation. This dynamic term acts to reduce the Hubble tension. A higher effective Omega_r in the early universe reduces the sound horizon at the epoch of recombination. PBH mass loss also influences fits to the equation of state parameter, w, at low redshift. The naive N-body modelling presented here suggests investigation with tried and tested cosmology codes should be carried out, by introducing mass losing PBHs and starting the evolution as early as practicable.
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https://arxiv.org/abs/2601.07106
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aeff60c63944b4791adf692c2249847f8a6fab1cdbf0fcdcea145dcdbc649088
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2026-01-13T00:00:00-05:00
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The Hierarchical Structure of the Open Cluster NGC 752
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arXiv:2601.07127v1 Announce Type: new Abstract: The structure of open clusters provides key insights into their evolution and the dynamics of the Milky Way. Using Gaia DR3 data, we applied a hierarchical clustering algorithm to the open cluster NGC 752 based on the kinematical information and identified four substructures corresponding to different stages of disintegration. The cluster exhibits a pronounced signature of mass segregation. Its outer members show a clear expansion trend with a velocities of 0.25 $\rm{km~s^{-1}}$ in the plane of the sky. In addition, the system shows a projected rotational pattern with an angular velocity of approximately 0.03 $\rm{rad~Myr^{-1}}$. We also identified a correlation between the escape times of disturbed members and the epochs at which the cluster crossed the Galactic disk, highlighting the role of Galactic tidal forces in accelerating cluster dissolution. We conclude that hierarchical clustering based on projection bounding energy is effective for studying the internal structure of star clusters, but it has limitations when dealing with unconstrained structures such as tidal tails.
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https://arxiv.org/abs/2601.07127
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5bf282f39253b28b15ac339b402bbc6dae0db67ab3d070b9f094def6abcedd24
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2026-01-13T00:00:00-05:00
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Slow White Dwarf Mergers as a New Galactic Source of Trans-Iron Elements
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arXiv:2601.07151v1 Announce Type: new Abstract: The astrophysical origins of the heaviest stable elements that we observe today in the Solar System are still not fully understood. Recent studies have demonstrated that H-accreting white dwarfs (WDs) in a binary sys- tem exploding as type Ia supernovae could be an efficient p-process source beyond iron. However, both observational evidence and stellar models challenge the required frequency of these events. In this work, we calculate the evolution and nucleosynthesis in slowly merging carbon-oxygen WDs. As our models approach the Chandrasekhar mass during the merger phase, the 22Ne(a,n)25Mg neutron source reaction is activated in the external layers of the primary WD, where the carbon-rich material accreted from the secondary WD is burned via the 12C+12C reaction, which provides the necessary {\alpha}-particles via the 12C(12C,{\alpha})20Ne channel. The resulting neutron capture abundance distribution closely resembles a weak s-process one and peaks at Zr, which is overpro- duced by a factor of 30 compared to solar. The mass of the most external layers enriched in first-peak s-process elements crucially depends on the 12C+12C re- action rate, ranging between 0.05 Msun and ~0.1 Msun. These results indicate that slow white dwarf mergers can efficiently produce the lightest p-process iso- topes (such as 74Se, 78Kr, 84Sr, 92Mo and 94Mo) via {\gamma}-induced reactions if they explode via a delayed detonation mechanism, or eject the unburned external layers highly enriched in first peak s-process elements in the case of a pure deflagration. In both cases, we propose for the first time that slow WD mergers in binary systems may be a new relevant source for elements heavier than iron.
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https://arxiv.org/abs/2601.07151
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476bf1ddf94085858943b86109a4041f7caa1ace71912751029e76aafa3ae80f
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2026-01-13T00:00:00-05:00
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Limit cycles and the climate history of Mars
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arXiv:2601.07159v1 Announce Type: new Abstract: Evidence for fluvial features and standing liquid water indicate that Mars was a warmer and wetter place in its past; however, climate models have historically been unable to produce conditions to yield a warm early Mars under the faint young sun. Some models invoke thick greenhouse atmospheres to produce continuously warm conditions, but others have argued that available geologic evidence is more consistent with short-duration and transient warming events on an otherwise cold Mars. One possibility of harmonizing these perspectives is that early Mars experienced climate limit cycles that caused the climate to oscillate between short periods of warmth and prolonged periods of glaciation, due to modulation of greenhouse warming by the carbonate-silicate cycle. This study suggests that episodic limit cycling during the Noachian and Hesperian periods provides a hypothetical explanation for the timing and formation of fluvial features on Mars. A schematic time-forward trajectory of the full history of Mars is calculated using an energy balance climate model, which includes an active carbonate-silicate cycle, instellation changes due to the sun's main sequence evolution, variations in the obliquity of Mars, and supplemental warming from additional greenhouse gases beyond carbon dioxide alone. These calculations demonstrate the viability of a climate history for Mars involving episodic limit cycling to enable the formation of the valley networks at 4.1-3.5 Ga and delta features at 3.3-3.0 Ga, interspersed with cold stable climates and ending in the late Amazonian in a carbon dioxide condensation regime. This schematic climate trajectory provide a plausible narrative that remains consistent with available geologic data, and further exploration of warming mechanisms for the climate of Mars should consider the possibility of episodic transient events driven by carbonate-silicate limit cycling.
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https://arxiv.org/abs/2601.07159
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02cb16513197e12d14b4fda00354d87fc60053660e1fbc1ce9b6e901c864a59d
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2026-01-13T00:00:00-05:00
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First Submillimeter Lights from Dome A: Tracing the Carbon Cycle in the Feedback of Massive Stars
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arXiv:2601.07162v1 Announce Type: new Abstract: The cycling of carbon between its ionized, atomic, and molecular phases shapes the chemical compositions and physical conditions of the interstellar medium (ISM). However, ground-based studies of the full carbon cycle have been limited by atmospheric absorption. Dome~A, the most promising site for submillimeter astronomy, has long resisted successful submillimeter astronomical observations. Using the 60~cm Antarctic Terahertz Explorer, we present the first successful CO ($4-3$) and [CI] ($^3P_1 - ^3P_0$) mapping observations of two archetypal triggered massive star-formation regions at Dome~A. These data, together with archival [CII], provide the first complete characterization of all three carbon phases in these environments. We find elevated C$^{0}$/CO abundance ratios in high-extinction regions, plausibly driven by deep penetration of intense radiation fields from massive stars into a clumpy ISM. These findings mark a major milestone for submillimeter astronomy at Dome~A and offer valuable insights into the impact of massive star feedback on the surrounding ISM.
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https://arxiv.org/abs/2601.07162
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9ee54e394e24cf2942b37593707b2b52587e6205b3a95e4944e91f707c582aac
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2026-01-13T00:00:00-05:00
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A Study Revealing Physical Attributes of Supernova Remnant in G321.3-3.9
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arXiv:2601.07170v1 Announce Type: new Abstract: We present a radio analysis of the recently identified supernova remnant G321.3-3.9 using archival multi-wavelength data spanning 88-2304 MHz. The source exhibits an elliptical shell-like morphology (1.3 deg x 1.7 deg) and a relatively flat non-thermal spectral index of alpha = -0.40 +/- 0.03. The distance is estimated using both the Sigma-D relation (1.6-2.9 kpc) and tentative associations with HI structures, the latter suggesting a near-side solution of 2.5-3.3 kpc, though the physical connection remains uncertain.
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https://arxiv.org/abs/2601.07170
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559ba6c97ad1931c116316c268d2d3310f83f7b1f6e2e6212311627896faa331
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2026-01-13T00:00:00-05:00
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Does the radio-active phase of XTE~J1810$-$197 recur following the same evolutionary pattern?
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arXiv:2601.07173v1 Announce Type: new Abstract: Magnetars are the most strongly magnetized compact objects known in the Universe and are regarded as one of the primary engines powering a variety of enigmatic, high-energy transients. However, our understanding of magnetars remains highly limited, constrained by observational sample size and radiative variability. XTE~J1810$-$197, which re-entered a radio-active phase in 2018, is one of only six known radio-pulsating magnetars. Leveraging the distinctive capability for simultaneous dual-frequency observations, we utilized the Shanghai Tianma Radio Telescope (TMRT) to monitor this magnetar continuously at both 2.25 and 8.60~GHz, capturing its entire evolution from radio activation to quenching. This enabled precise characterization of the evolution in its integrated profile, spin frequency, flux density, and spectral index ($\alpha$, defined by $S \propto f^{\alpha}$). The first time derivative of its spin frequency $\dot{\nu}$ passed through four distinct phases -- rapid decrease, violent oscillation, steady decline, and stable recovery -- before returning to its pre-outburst value concomitant with the cessation of radio emission. Remarkably, both the amplitudes and the characteristic time-scales of these $\dot{\nu}$ variations match those observed during the previous outburst that began in 2003, providing the first demonstration that post-outburst rotational evolution and radiative behavior in a magnetar are repeatable. A twisted-magnetosphere model can qualitatively account for this repeatability as well as for the progressive narrowing and abrupt disappearance of the radio pulse radiation, thereby receiving strong observational support.
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https://arxiv.org/abs/2601.07173
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a4f8c63fd9b03e4dd9fca36c3e2d338729fb695145751fb147a35c9c3dcd9b23
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2026-01-13T00:00:00-05:00
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The stellar initial mass function of nearby young moving groups
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arXiv:2601.07184v1 Announce Type: new Abstract: The solar neighbourhood is populated by nearby, young moving groups (NYMGs) of stars that are candidates to be remnants of individual stellar clusters and associations, currently dispersing in the galactic disc. To derive the initial mass function (IMF) of a large sample of NYMGs, we developed and applied an algorithm that uses photometry and astrometry from Gaia DR3 to detect NYMGs in a kinematic space. We inferred individual masses from the photometry of both the detected and the previously known candidates. We estimated the IMFs for 33 groups, 30 of them for the first time, in an average mass range $0.1M_\odot1~M_\odot$. We detected 4166 source candidate members of 44 known groups, including 2545 new candidates. We recovered 44-54\% of the literature candidates and estimated a contamination rate from old field stars of 16-24\%. The candidates of the detected groups distribute along young isochrones, which suggests that they are potential members of NYMGs. Parameterizations of both the average of the 33 IMFs based on our detections ($m_c=0.25\pm0.17~M_{\odot}$, $\sigma_c=0.45\pm0.17$, and $\alpha=-2.26\pm0.09$) and the one based on the known candidates from the literature ($m_c=0.22\pm0.14~M_{\odot}$, $\sigma_c=0.45\pm0.17$, and $\alpha=-2.45\pm0.06$) are in agreement with the IMF parameterization of the solar neighbourhood and young stellar associations. Our parameterization of the average IMF together with the distribution of the detected group members along young isochrones provide strong evidence suggesting that the NYMGs are remnants of individual stellar associations and clusters and that there are no systematic biases in our detection and in the literature in the range $0.1M_{\odot}<10$.
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https://arxiv.org/abs/2601.07184
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7ba2c30af3464e3feaa192c5dbba2f2bd5234093d3b284d8b3951ad888252a33
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2026-01-13T00:00:00-05:00
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Broad line regions behind haze: Intrinsic shape of Br$\gamma$ line and its origin in a type-1 Seyfert galaxy
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arXiv:2601.07211v1 Announce Type: new Abstract: The broad-line region (BLR) of active galactic nuclei (AGN) is an essential component, yet its small size keeps its origin, structure, and kinematics uncertain. Infrared interferometry with VLTI/GRAVITY is now resolving BLR-scale emission, with data for NGC 3783 consistent with a rotating, geometrically thick configuration. However, the processes shaping the spectra remain poorly constrained, and the cloud models are tuned phenomenologically rather than derived from first-principles predictions. We address this by coupling three-dimensional radiation-hydrodynamic (RHD) simulations of gas around a supermassive black hole with radiative-transfer calculations using Cloudy, comparing the results to the SINFONI Br$\gamma$ profile of NGC 3783. We find that Br$\gamma$ arises from ionized gas in the surface of the rotating thin disk, with electron temperatures of approximately $T_e \approx 10^4$ K and number densities of $n_e \approx 10^8-10^{11}$ cm$^{-3}$. However, the intrinsic line profile produced by the RHD kinematics is narrower than observed and displays substructure. An approximate treatment of the electron scattering suggests that scattering in surrounding diffuse ionized gas significantly broadens and smooths the intrinsic Br$\gamma$ profile, making it consistent with the observed profile. This scattering medium has an electron temperature of $10^4 - 10^5$ K, and a number density of $n \lesssim 10^8$ cm$^{-3}$. Although a best-fit viewing angle of $\approx 15$ deg is suggested, the scattered line is notably less sensitive to inclination than the intrinsic line. The observed BLR profiles may be understood as the intrinsic emission viewed through an electron-scattering haze, such that some spectral detail is plausibly redistributed rather than seen directly.
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https://arxiv.org/abs/2601.07211
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8e1f1bc86132eee5b185a7f1c505516483cb6f1d8858a72bfa44377c7eff6cd7
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2026-01-13T00:00:00-05:00
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The magnetic helicity driven solar-type dynamo
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arXiv:2601.07244v1 Announce Type: new Abstract: (1)The previous theoretical studies showed that in the presence of the small-scale dynamo the large-scale vorticity can produce the the divergent-type helicity flux breaking the equatorial reflection symmetry of the magnetic fluctuations in the stellar convection zone. This effect was called the new Visniac flux (hereafter the NV flux). Similarly to the $\alpha$ effect, the NV flux is able to maintain the large-scale turbulent dynamo. 2) Methods:Using the mean-field dynamo model we study the effect of the NV flux on the solar type dynamos. We found that the NV flux results to a increase of the dynamo efficiency for the turbulent generation of the large-scale poloidal magnetic field of the Sun. The dynamic effect of the NV flux on the magnetic field evolution results into concentrating the dynamo waves toward the equator. Using the numerical simulations of the mean-field dynamo model we compare the helicity production rates by the turbulent dynamo effects, like the $\alpha$ effect and the NV flux. We found that the new dynamo source can produce the large-scale dynamo even if the kinetic $\alpha$ effect is zero.3) Conclusions:The new findings suggest the crucial role of the large-scale vorticity and fluctuating magnetic field in the large-scale dynamo inside the stellar convection zones.
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https://arxiv.org/abs/2601.07244
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906e4b94d7a1b31da4a033c056566ca1279e647042118e641f00e1081fcb664b
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2026-01-13T00:00:00-05:00
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What can be learnt from UHECR anisotropies observations Paper III: Update with new data and Galactic magnetic fields models
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arXiv:2601.07259v1 Announce Type: new Abstract: Context. At large angular scales, the Pierre Auger Observatory has reported a significant dipole modulation in right ascension, while at intermediate angular scales, localized flux excesses have been identified by both the Auger and Telescope Array collaborations. These observations were investigated in the first two papers of this series. Aims. We examine the implications of these anisotropy measurements and assess to what extent they can be used to constrain the origin of UHECRs and the astrophysical or physical parameters of viable source scenarios. Methods. As in the first two papers of this series, we generate realistic UHECR sky maps for a wide range of astrophysical models consistent with current spectral and composition constraints, assuming that UHECR sources trace the distribution of galaxies in the Universe. We update our previous studies by incorporating the most recent models of the Galactic magnetic field and apply the same large- and intermediate-scale anisotropy analyses as those used by the Auger Collaboration to simulated datasets with current experimental exposure. Results. The main novelty of this third paper is the improved compatibility between simulations and data, in particular regarding the reconstructed dipole direction, when using several of the recently proposed Galactic magnetic field models. Despite this progress, our main conclusions remain unchanged: although the observed anisotropies are compatible with an extragalactic origin of UHECRs, present data and magnetic-field uncertainties do not allow strong constraints to be placed on the nature, spatial distribution, or density of UHECR sources. Conclusions. Further progress in the interpretation of UHECR anisotropies will require improved constraints on cosmic magnetic fields, advances in source modeling, and significantly larger experimental exposures
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https://arxiv.org/abs/2601.07259
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02cb3d388b5d0bcccd7f707dd1b203b863b071800a58a4514c77c3ebf1983ffc
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2026-01-13T00:00:00-05:00
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Photometric Redshift Estimation Using Scaled Ensemble Learning
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arXiv:2601.07292v1 Announce Type: new Abstract: The development of the state-of-the-art telescopic systems capable of performing expansive sky surveys such as the Sloan Digital Sky Survey, Euclid, and the Rubin Observatory's Legacy Survey of Space and Time (LSST) has significantly advanced efforts to refine cosmological models. These advances offer deeper insight into persistent challenges in astrophysics and our understanding of the Universe's evolution. A critical component of this progress is the reliable estimation of photometric redshifts (Pz). To improve the precision and efficiency of such estimations, the application of machine learning (ML) techniques to large-scale astronomical datasets has become essential. This study presents a new ensemble-based ML framework aimed at predicting Pz for faint galaxies and higher redshift ranges, relying solely on optical (grizy) photometric data. The proposed architecture integrates several learning algorithms, including gradient boosting machine, extreme gradient boosting, k-nearest neighbors, and artificial neural networks, within a scaled ensemble structure. By using bagged input data, the ensemble approach delivers improved predictive performance compared to stand-alone models. The framework demonstrates consistent accuracy in estimating redshifts, maintaining strong performance up to z ~ 4. The model is validated using publicly available data from the Hyper Suprime-Cam Strategic Survey Program by the Subaru Telescope. Our results show marked improvements in the precision and reliability of Pz estimation. Furthermore, this approach closely adheres to-and in certain instances exceeds-the benchmarks specified in the LSST Science Requirements Document. Evaluation metrics include catastrophic outlier, bias, and rms.
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https://arxiv.org/abs/2601.07292
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835d5f36d3eca7267e1256f54d39b8034ab835e5be109e87fd27b7cbf6715538
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2026-01-13T00:00:00-05:00
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WISE/CatWISE Constraints on Dysonian Waste-Heat Technosignatures in Nearby Galaxies
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arXiv:2601.07297v1 Announce Type: new Abstract: We search for galaxy-scale (Dysonian) waste heat in the mid-infrared using WISE. Starting from the 2MASS Redshift Survey (2MRS), we cross-match to CatWISE2020 and AllWISE, apply standard MIR AGN/starburst vetoes (Stern, Assef R90, Jarrett), and treat W1 and W2 as stellar baselines and W3 and W4 as constraining bands. For each galaxy and for blackbody waste heat temperatures T=150-600 K, we convert W3/W4 photometry into conservative 3-sigma per-galaxy upper limits on the bolometric waste heat luminosity using the WISE bandpass (RSR) color correction. The resulting distributions have median caps of ~(5-9) x 10^8 L_sun across T=150-600 K. Aggregated at the population level, the one-sided 95% upper bound on the fraction of nearby galaxies that could host waste heat above a given threshold monotonically decreases with threshold and asymptotes to ~1/6500 at high thresholds (set by the sample size). Sensitivity transitions from W4 at T = 300K. Interpreted with the AGENT formalism, a fiducial Milky Way like stellar luminosity L_=3 x 10^10 L_sun implies typical per galaxy caps of alpha = L_wh/L_ = 21% of a Milky Way-like stellar luminosity into ~ 300K waste heat.
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https://arxiv.org/abs/2601.07297
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de76c402e2fdde3e51cc6fadfb5453078b276f4b03c22e872e2ae9ea8d89996b
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2026-01-13T00:00:00-05:00
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Emulator-Based Inference of Cosmological Subgrid Models
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arXiv:2601.07306v1 Announce Type: new Abstract: The formation of structure in the Universe at large scales is dominated by gravity, with baryonic physics becoming significant at $\sim{\rm Mpc}$ scales. To capture the impact of baryonic physics, cosmological simulations must model gas dynamics and a host of relevant astrophysical processes. A recent extension of the Hardware/Hybrid Accelerated Cosmology Code (HACC) couples its gravity solver with a modern smoothed particle hydrodynamics method. This extension incorporates sub-resolution models for chemical enrichment, black hole and star formation, AGN kinetic and thermal feedback, supernova-driven feedback, galactic winds, and metal-line cooling. We present an inference framework based on high-fidelity emulators to aid in model calibration against observational targets, e.g., the galaxy stellar mass function, radial gas density profiles, and the cluster gas fraction. The emulators are trained on simulation suites comprising 64 boxes with side-length $128\,h^{-1}$Mpc and 16 boxes with side-length $256\,h^{-1}$Mpc with $2\times 512^3$ and $2\times 1024^3$ particles, respectively. Our analysis reveals two distinct AGN kinetic feedback modes -- a low-feedback mode yielding strong agreement with the observed radial gas density profiles of massive X-ray clusters, and a high-feedback mode providing a better fit to cluster gas fraction data, but systematically underestimating gas densities in inner regions.
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https://arxiv.org/abs/2601.07306
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b899da64ac0a12856d6555cc3f82b8063bea1e739be4051e7214d5be725f0a44
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2026-01-13T00:00:00-05:00
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Multi-wavelength properties of changing-state active galactic nuclei: I. the evolution of soft excess and X-ray continuum
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arXiv:2601.07337v1 Announce Type: new Abstract: Changing-state active galactic nuclei (CSAGNs) exhibit rapid variability, with mass accretion rates that can change by several orders of magnitude in a few years. This provides us with a unique opportunity to study the evolution of the inner accretion flow almost in real time. Here, we used over 1000 observations to study the broadband X-ray spectra of a sample of five CSAGNs, spanning three orders of magnitude in Eddington ratio ($\lambda_{\rm Edd}$), using phenomenological models to trace the evolution of key spectral components. We derive several fundamental parameters, such as the photon index, soft excess strength, reflection strength, and luminosities of the soft excess and primary continuum. We find that the soft excess and primary continuum emissions show a very strong positive correlation ($p \ll 10^{-10}$), suggesting a common physical origin. The soft excess strength does not show any dependency on the reflection parameter, suggesting that in these objects the soft excess is not dominated by a blurred ionized reflection process. On the other hand, the strength of the soft excess is found to be strongly positively correlated with the Eddington ratio ($p \ll 10^{-10}$), and we find that the soft excess vanishes below $\log \lambda_{\rm Edd} \sim -2.5$. Moreover, we find a clear `V'-shaped relation for $\Gamma-\lambda_{\rm Edd}$, with a break at $\log \lambda_{\rm Edd} = -2.47 \pm 0.09$. Our findings indicate a change in the geometry of the inner accretion flow at low Eddington ratios, and that the soft excess is primarily produced via warm Comptonization.
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https://arxiv.org/abs/2601.07337
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4fce30814deb78a7380b3d699e058330f70b002174dbe7a5147fcb6daeff98e4
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2026-01-13T00:00:00-05:00
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New $H(z)$ measurement at Redshift = 0.12 with DESI Data Release 1
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arXiv:2601.07345v1 Announce Type: new Abstract: The Hubble parameter ($H(z)$) is a function of the redshift and a reliable measurement is very important to understand the expansion history of the Universe. In this work, we perform full-spectrum fitting using BAGPIPES on more than four thousand massive, passively evolving galaxies released by the DESI collaboration to estimate their cosmological-independent stellar ages and star-formation histories, and derive a new measurement of $H(z=0.12)=71.33 \pm 4.20~{\rm km~s^{-1}~Mpc^{-1}}$, which is well consistent with those derived in other ways.
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https://arxiv.org/abs/2601.07345
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a6a8fbfc543a9d0f9c02da529974a15b98c97442b52e5ba6de7f11917d2cac63
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2026-01-13T00:00:00-05:00
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Direct detection of the non-thermal X-ray emission from the Arches star cluster
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arXiv:2601.07357v1 Announce Type: new Abstract: The compact stellar clusters have emerged as particularly promising candidates for cosmic rays (CR) accelerators. The star clusters, recently observed in gamma-rays, are also known sources of non-thermal X-ray emission, which is due to synchrotron or inverse-Compton scattering of relativistic electrons. Thus, the search for the non-thermal X-ray emission from stellar clusters is of particular interest. Until recent time the X-ray emission of the Arches star cluster in the Galactic Center was mixed with non-thermal emission of the surrounding molecular cloud, associated with reflection of hard X-ray irradiation. This reflected emission has been observed to fade, giving us a chance to characterize intrinsic non-thermal emission of the Arches cluster. In this work we demonstrate that Fe K_alpha line emission at 6.4 keV, attributed to the reflected non-thermal emission of the molecular cloud in 2000-2010, is not detected in deep observations with XMM-Newton in 2020 and Chandra in 2022, leaving stellar cluster well isolated. We showed that the Arches non-thermal emission is localized in the cluster's core and characterized by a relatively weak, hard (Gamma~1.5) power-law spectral continuum with 2-10 keV flux of ~10E-13 ergs/s/cm^2.
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https://arxiv.org/abs/2601.07357
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cba0c47d2b892dfb83f220964b5f03d39310237606b077899e074a520abae2cb
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2026-01-13T00:00:00-05:00
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Strong Evidence for Dark Sector Interactions
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arXiv:2601.07361v1 Announce Type: new Abstract: Recent DESI baryon acoustic oscillation data reveal deviations from $\Lambda$CDM cosmology, conventionally attributed to dynamical dark energy (DE). We demonstrate that these deviations are equally, if not better, explained by interactions between dark matter and dark energy (IDE), without requiring a time-varying DE equation of state. Using a unified framework, we analyze two IDE models--coupled quintessence and coupled fluid--against the latest CMB (Planck, ACT, SPT), DESI BAO, and SN (including DES-Dovekie recalibrated) data. Both IDE scenarios show robust evidence for non-vanishing interactions at the 3-5$\sigma$ level, with marginalized constraints significantly deviating from the $\Lambda$CDM limit. This preference persists even under DES-Dovekie SN recalibration, which weakens dynamical DE evidence. Crucially, for the same number of free parameters, IDE models provide fits to low- and high-redshift data that match or exceed the performance of the CPL dynamical DE parametrization. Our results establish IDE as a physically motivated alternative to dynamical DE, highlighting the necessity of future cosmological perturbation measurements (e.g., weak lensing, galaxy clustering) to distinguish between these paradigms.
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https://arxiv.org/abs/2601.07361
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cfa5a86fedfd5750db6a810e0d2a02d502462ad091b8012fc5a506d6a7e693d6
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2026-01-13T00:00:00-05:00
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Expanding the C$_3$H$_6$O$_2$ Isomeric Interstellar Inventory: Discovery of Lactaldehyde and Methoxyacetaldehyde in G+0.693-0.027
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arXiv:2601.07365v1 Announce Type: new Abstract: The tentative detection of 3-hydroxypropanal (HO(CH$_2$)$_2$C(O)H) toward the Galactic center molecular cloud G+0.693-0.027 prompts a systematic survey in this source aimed at detecting all C$_3$H$_6$O$_2$ isomers with available spectroscopy. We use an ultra-deep broadband spectral survey of G+0.693-0.027, carried out with the Yebes 40 m and IRAM 30 m telescopes, to conduct the astronomical search. We report the first interstellar detection of lactaldehyde (CH$_3$CH(OH)C(O)H) and methoxyacetaldehyde (CH$_3$OCH$_2$C(O)H), together with the second detections (i.e., confirmation) of methyl acetate (CH$_3$C(O)OCH$_3$) and hydroxyacetone (CH$_3$C(O)CH$_2$OH), and new detections in this source of both $anti$- and $gauche$- conformers of ethyl formate (CH$_3$CH$_2$OC(O)H), the latter tentatively. In contrast, neither propionic acid, CH$_3$CH$_2$C(O)OH, nor glycidol, c-CH$_2$OCHCH$_2$OH (i.e., the most and the least stable species within the C$_3$H$_6$O$_2$ family, respectively) were detected, and we provide upper limits on their fractional abundances of $\leq$1.5 $\times$ 10$^{-10}$ and $\leq$3.7 $\times$ 10$^{-11}$. Interestingly, all C$_3$H$_6$O$_2$ isomers can be synthesized through radical-radical reactions on the surface of dust grains, ultimately tracing back to CO as the parent molecule. We suggest that formation of the detected isomers is mainly driven by successive hydrogenation of CO, producing CH$_3$OH and CH$_3$CH$_2$OH as the primary parent species. Conversely, propionic acid is thought to originate from the oxygenation of CO via the HOCO intermediate, which help us rationalize its non-detection. Overall, our findings notably expand the known chemical inventory of the interstellar medium and provide direct observational evidence that increasingly complex chemistry involving O-bearing species occurs in space.
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https://arxiv.org/abs/2601.07365
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8d459661350a664c61abc53910f5451b4a6125264a3f628bd4628c8699b1353c
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2026-01-13T00:00:00-05:00
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Possible evidence for a pair-instability supernova nature of ultra-early JWST sources
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arXiv:2601.07374v1 Announce Type: new Abstract: Recent JWST observations have revealed a population of unexpectedly bright sources at ultra-high redshift ($z > 15$), challenging current models of early galaxy formation. One extreme example is 'Capotauro', an F356W-dropout identified in the CEERS survey and initially interpreted as a luminous galaxy at $z\sim30$, but subsequently found to be variable over an $\sim 800$ day baseline. Motivated by this variability, we explore the alternative hypothesis that Capotauro is a pair-instability supernova (PISN) originating from a massive ($250-260\,M_\odot$), metal-free star. Using state-of-the-art PISN light curves, spectral energy distributions, and synthetic spectra, we show that a PISN at $z\simeq 15$ can plausibly reproduce the observed brightness, temporal evolution, photometry, and NIRSpec spectrum. We compare this scenario with alternative interpretations, including a local Y0 brown dwarf, and discuss observational tests to discriminate among them. If confirmed, this event would provide a rare window onto Population III stars, and highlights the importance of transient contamination in ultra-high redshift galaxy samples.
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https://arxiv.org/abs/2601.07374
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2707ae460b3ab3cbdb8890cec816e5ffc5c65f944f7687b9101ad06833f20e8c
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2026-01-13T00:00:00-05:00
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Temporal variability of polarization in blazars
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arXiv:2601.07387v1 Announce Type: new Abstract: We investigate the temporal variability of polarization of synchrotron radiation from blazar jets. Multiwavelength observations revealed high-amplitude rotations of the electric vector position angle (EVPA), both in the optical and in the X-rays. More often, the polarization degree and the EVPA show a seemingly erratic variability. To interpret these observations, we present a geometric and deterministic model in which off-axis, compact emitting features (i.e.,~blobs) propagate along the jet with the local velocity of the flow. The dynamics of the blobs is determined by the jet electromagnetic fields, which are calculated self-consistently using an analytical model of magnetically dominated outflows. The jet is axisymmetric, and its electromagnetic fields do not have a turbulent component. We show that the observed polarization is sensitive to the initial spatial configurations of the blobs. For the same jet structure, we observe several remarkably complex polarization patterns, including large EVPA rotations of $180^{\circ}$ or more in both directions and more erratic fluctuations. Simultaneous high-amplitude variations of the polarization degree and the EVPA can coincide with peaks of the observed luminosity. However, seemingly uncorrelated variations are also possible. We discuss the feasibility of constraining the particle acceleration mechanism from multifrequency polarimetric observations.
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https://arxiv.org/abs/2601.07387
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b2764920db11742af75494cd1acc6488564518470b88077a8d93d592ef34287d
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2026-01-13T00:00:00-05:00
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Asymmetric distribution of Fe-peak elements in Cassiopeia A revealed by XRISM
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arXiv:2601.07394v1 Announce Type: new Abstract: The elemental abundances of the Fe-peak elements (such as Cr, Mn, Fe and Ni) and Ti are important for understanding the environment of explosive nuclear burning for the core-collapse supernovae (CC SNe). In particular, the supernova remnant Cassiopeia A, which is well known for its asymmetric structure, contains three ``Fe-rich blobs,'' and the composition of the Fe-peak elements within these structures could be related to the asymmetry of the supernova explosion. We report a highly asymmetric distribution of the Fe-peak elements in Cassiopeia A as revealed by XRISM observations. We found that the southeastern Fe-rich region has a significant Mn emission above the 4$\sigma$ confidence level, while the northwestern Fe-rich region has no clear signature. In addition to the significant difference in Mn abundance across these regions, our observations show that the Ti/Fe, Mn/Cr, and Ni/Fe ratios vary from region to region. The observed asymmetric distribution of Fe-peak elements could be produced by (1) the mixing of materials from different burning layers of the supernova, (2) the asymmetric distribution of the electron fraction in the progenitor star and/or (3) the local dependence of the neutrino irradiation in the supernova innermost region. Future spatially resolved spectroscopy of Cassiopeia A using X-ray microcalorimeters will enable more detailed measurements of the distribution and composition of these elements, providing a unique tool for testing asymmetric supernova physics.
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https://arxiv.org/abs/2601.07394
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2f48b1787bc038599d3b5fd922baa5a32eb438a425448a8094b6b6d3672fb00f
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2026-01-13T00:00:00-05:00
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The converging gas flow around the infrared dark cloud G28.3
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arXiv:2601.07407v1 Announce Type: new Abstract: Aims: The G28.37+0.07 star-forming region is a prototypical infrared dark cloud (IRDC) located at the interface of a converging gas flow. This study characterizes the properties of this dynamic gas flow. Methods: Combining data from the Northern Extended Millimeter Array (NOEMA) with single-dish data from the IRAM30m observatory, we mapped large spatial scales (~81pc^2) at high angular resolution (7.0''x2.6'' corresponding ~2.3x10^4au or ~0.1pc) down to core scales. The spectral setup in the 3mm band covers many spectral lines as well as the continuum emission. Results: The data reveal the proposed west-east converging gas flow in all observed dense gas tracers. We estimate a mass-flow rate along that flow around 10^-3M_sun/yr. Comparing these west-east flow rates to infall rates toward sources along the line of sight, the gas flow rates are roughly a factor of 25 greater than than those along the line of sight. This confirms the dominance of longitudinal motions along the converging gas flow in G28.37. For comparison, in the main north-south IRDC formed by the west-east converging gas flow, infall rates along the line of sight are about an order of magnitude greater than those along the west-east flow. In addition to the kinematic analysis, a comparison of CH_3CN-derived gas temperatures with Herschel-derived dust temperatures typically show higher gas temperatures toward high-density sources. We discuss whether mechanical heating from the conversion of the flow's kinetic energy into thermal energy may explain some of the observed temperature differences. Conclusions: The differences between flow rates along the converging flow, perpendicular to it, and toward the sources at the IRDC center indicate that at the interfaces of converging gas flows - where most of the active star formation takes place - originally more directed gas flows can convert into multidirectional infall motions.
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https://arxiv.org/abs/2601.07407
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b30c34e11013e53cfaea8c315454cc3ff6f6b8078aefe4918d7ae75f597776a7
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2026-01-13T00:00:00-05:00
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Characterization of two new transiting sub-Neptunes and a terrestrial planet around M-dwarf hosts
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arXiv:2601.07414v1 Announce Type: new Abstract: We report the confirmation of three transiting exoplanets orbiting TOI-1243 (LSPM~J0902+7138), TOI-4529 (G~2--21), and TOI-5388 (Wolf~346) that were initially detected by TESS through ground-based photometry and radial velocity follow-up measurements with CARMENES. The planets present short orbital periods of $4.65$, $5.88$, and $2.59$ days, and they orbit early-M dwarfs (M2.0V, M1.5V, and M3.0V, respectively). We were able to precisely determine the radius of all three planets with a precision of $< 7\, \%$, the mass of TOI-1243 b with a precision of $19\, \%$, and upper mass limits for TOI-4529 b and TOI-5388 b. The radius of TOI-1243 b is $2.33\pm0.12\, {R_{\oplus}}$, its mass is $7.7 \pm 1.5\,{M_{\oplus}}$, and the mean density is $0.61 \pm 0.15 \, {\rho_\oplus}$. The radius of TOI-4529 b is $1.77 ^{+0.09}_{-0.08} \, {R_{\oplus}}$, the $3 {\sigma}$ upper mass limit is $4.9 \, {M_{\oplus}}$, and the $3 {\sigma}$ upper density limit is $0.88\, {\rho_\oplus}$. The third planet, TOI-5388 b, is Earth-sized with a radius of $0.99 ^{+0.07}_{-0.06} \, {R_{\oplus}}$, a $3 {\sigma}$ upper mass limit of $2.2 \, {M_{\oplus}}$, and a $3 {\sigma}$ upper density limit of $2.2\, {\rho_\oplus}$. While TOI-5388 b is most probably rocky, given its Earth-like radius, TOI-1243 b and TOI-4529 b are located in a highly degenerate region in the mass-radius space. TOI-4529 b appears to lean toward a water-world composition. TOI-1243 b has enough mass to host a significant H-He envelope, although a water-world and pure rocky compositions are also consistent with the data. Our analysis indicates that future atmospheric observations using JWST can aid in determining their real composition. The sample of small planets around M dwarfs is widely used to understand planet formation and composition theories, and our study adds three planets to this sample.
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https://arxiv.org/abs/2601.07414
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879299ec09f4ee4cca599feb98a223c4978aa48c0c1e2b53d3c4d95a7c32975c
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2026-01-13T00:00:00-05:00
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A free-fall-based switching criterion for P^3 T N-body methods in collisional stellar systems
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arXiv:2601.07425v1 Announce Type: new Abstract: The P$^3$T scheme is a hybrid method for simulating gravitational $N$-body systems. It combines a fast particle-tree (PT) algorithm for long-range forces with a high-accuracy particle-particle (PP, direct $N$-body) solver for short-range interactions. Preserving both PT efficiency and PP accuracy requires a robust PT-PP switching criterion. We introduce a simple free-fall-based switching criterion for general stellar systems, alongside the commonly used velocity-dispersion-based ($\sigma$-based) criterion. Using the \textsc{petar} code with the P$^3$T scheme and slow-down algorithmic regularization for binaries and higher-order multiples, we perform extensive simulations of star clusters to evaluate how each criterion affects energy conservation and binary evolution. For systems in virial equilibrium, we find that the free-fall-based criterion is generally more accurate for low-$\sigma$ or loose clusters containing binaries, whereas the $\sigma$-based criterion is better suited for high-$\sigma$ systems. Under subvirial or fractal initial conditions, both criteria struggle to maintain high energy conservation; however, the free-fall-based criterion improves as the tree timestep is reduced, whereas the $\sigma$-based degrades due to its low-accuracy treatment of two-body encounters.
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https://arxiv.org/abs/2601.07425
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c0810cce5939444850cd57fd3e81afad419a448a158d61fcd0d95b8833de811d
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2026-01-13T00:00:00-05:00
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A Study of Two Type IIb Supernovae: SNe 2008aq and 2019gaf
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arXiv:2601.07450v1 Announce Type: new Abstract: We present photometric and spectroscopic studies of two core-collapse supernovae (SNe) 2008aq and 2019gaf in the optical wavelengths. Light curve and spectral sequence of both the SNe are similar to those of other Type IIb SNe. The pre-maximum spectrum of SN~2008aq showed prominent H $\alpha$ lines, the He lines started appearing in the near maximum spectrum. The near maximum spectrum of SN~2019gaf shows shallow H$\alpha$ absorption and He lines with almost similar strength. Both the SNe show transition from hydrogen-dominated spectra to helium-dominated spectra within a month after maximum brightness. The velocity evolution of SN~2008aq matches well with those of other well-studied Type IIb SNe, while SN~2019gaf shows higher velocities. Close to maximum light, the H $\alpha$ and He I line velocities of SN~2019gaf are $\sim$ 2000 km sec$^{-1}$ and $\sim$ 4000 km sec$^{-1}$ higher than other well-studied Type IIb SNe. Semi-analytical modeling indicates SN~2019gaf to be a more energetic explosion with a smaller ejecta mass than SN~2008aq. The zero-age main-sequence (ZAMS) mass of the progenitor estimated using the nebular spectra of SN~2008aq ranges between 13 to 20 M$_\odot$, while for SN~2019gaf, the inferred ZAMS mass is between 13 to 25 M$_\odot$. The [O I] to [Ca II] lines flux ratio favors a less massive progenitor star in a binary system for both the SNe.
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https://arxiv.org/abs/2601.07450
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fc7bd642aad0e5f02d4904a4103157f2cc324e3b9fd3d649f78cd64b7430920b
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2026-01-13T00:00:00-05:00
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Exoplanet transit search at the detection limit: detection and false alarm vetting pipeline
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arXiv:2601.07465v1 Announce Type: new Abstract: One of the primary mission goals of the Kepler space telescope was to detect Earth-like terrestrial planets in the habitable zone around Sun-like stars. These planets are at the detection limit, where the Kepler detection and vetting pipeline produced unreliable planet candidates. We present a novel pipeline that improves the removal of localized defects prior to the planet search, improves vetting at the level of individual transits and introduces a Bayes factor test statistic and an algorithm for extracting multiple candidates from a single detection run. We show with injections in the Kepler data that the introduced novelties improve pipeline's completeness at a fixed false alarm rate. We apply the pipeline to the stars with previously identified planet candidates and show that our pipeline successfully recovers the previously confirmed candidates, but flags a considerable portion of unconfirmed candidates as likely false alarms, especially in the long period, low signal-to-noise ratio regime. In particular, several known Earth-like candidates in the habitable zone, such as KOI 8063.01, 8107.01 and 8242.01, are identified as false alarms, which could have a significant impact on the estimates of $\eta_{\oplus}$, i.e., the occurrence of Earth-like planets in the habitable zone.
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https://arxiv.org/abs/2601.07465
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ce8fb25a5c00b55e89ec98f3320460649849ba8603bf23311ad64bb7ea8a7bb5
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2026-01-13T00:00:00-05:00
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Instantaneous thermally-driven erosion can explain dearth of dark near-Sun asteroids
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arXiv:2601.07471v1 Announce Type: new Abstract: Recent models of the near-Earth asteroid population show that asteroids must be super-catastrophically destroyed when they evolve to orbits with perihelion passages well inside of Mercury's orbit. The heliocentric distances at which the disruptions typically occur are tens of solar radii, which is too far from the Sun for asteroids to be destroyed by sublimation and tidal disruption. The typical disruption distance also appears to be larger for darker asteroids. Here, by carrying out irradiance experiments in vacuum that replicate the conditions in the near-Sun environment, we show that CI meteorite simulants are destroyed within minutes when exposed to the level of solar irradiance encountered at heliocentric distances of up to about 0.2 au. Our results provide an explanation for the scarcity of dark, carbonaceous asteroids with perihelion distances less than 0.2 au, and for the observed mass-loss rate of the asteroid-like object 322P/SOHO~1 assuming its composition is similar to CI carbonaceous chondrites.
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https://arxiv.org/abs/2601.07471
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98f792d03e1dcf6c5a7a1aebdbf945cc74f336502da460ba65fab2e53e1b0083
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2026-01-13T00:00:00-05:00
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A Guided Unconditional Diffusion Model to Synthesize and Inpaint Radio Galaxies from FIRST, MGCLS and Radio Zoo
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arXiv:2601.07485v1 Announce Type: new Abstract: We present a masked guided approach for a denoising diffusion probabilistic model (DDPM) trained to generate and inpaint realistic radio galaxy images. We train the DDPM using the FIRST radio galaxy catalog, the Radio Galaxies Zoo and cutouts of the MGCLS catalog. We compared different statistical distributions to make sure that our unconditional approach produces morphologically realistic galaxies, offering a data-driven method to supplement existing radio datasets and support the development of machine learning applications in radio astronomy.
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https://arxiv.org/abs/2601.07485
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26ff40e2d416a5b2a959933bd8553d13ed0341f5306ae8b1fc3d7dee26da5de8
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2026-01-13T00:00:00-05:00
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Modified Gravity and the Origin of the Excess Radio Galaxy Number-Count Dipole
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arXiv:2601.07487v1 Announce Type: new Abstract: Recent analyses of wide-area radio-galaxy surveys have reported a statistically significant excess in the cosmic number-count dipole, with an amplitude exceeding the purely kinematic expectation of the standard $\Lambda$CDM model by a factor of $\sim 3$--$4$, quoted at a significance level of up to $5.4\sigma$. While residual observational systematics and local-structure effects cannot be definitively excluded, this result motivates the exploration of alternative physical interpretations beyond the minimal $\Lambda$CDM framework. We investigate whether Scalar--Tensor--Vector Gravity (STVG-MOG) can provide a consistent explanation for an enhanced large-scale anisotropic dipole without violating existing constraints from early-universe cosmology, the cosmic microwave background (CMB) dipole, galaxy dynamics, weak lensing, or the observed late-time matter power spectrum. The radio number-count dipole probes ultra-large-scale, anisotropic structure and coherent gravitational response, rather than virialized dynamics or linear growth alone. In STVG-MOG, a scale- and time-dependent effective gravitational coupling preserves standard cosmological evolution at early times and on small to intermediate scales, while amplifying gravitational response on gigaparsec scales. This scale-selective enhancement can increase the large-scale structure contribution to the radio dipole without overproducing power on smaller scales. If the observed dipole excess reflects a physical cosmological signal rather than residual systematics, STVG-MOG offers a viable and testable alternative interpretation. It is demonstrated that the radio dipole anomaly provides a novel probe of gravitational physics on the largest observable scales.
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https://arxiv.org/abs/2601.07487
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26a1c79ac59a4d9ffc0a68141ba2a49739d1a7dbdfe4362d4d9bd9d0de8c5e48
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2026-01-13T00:00:00-05:00
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The combined X-ray and $\gamma$-ray modeling of millisecond pulsars PSR J0030+0451 in the dissipative magnetospheres
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arXiv:2601.07491v1 Announce Type: new Abstract: Modeling of the NICER X-ray light curves of millisecond pulsars PSR J0030+0451 provides a strong evidence for the existence of non-dipole magnetic fields. We study the X-ray and $\gamma$-ray emission of PSR J0030+0451 in the dissipative dipole plus off-centred quadrupole magnetospheres. The dissipative FF+AE dipole magnetospheres by combining force-free (FF) and Aristotelian electrodynamics (AE) are solved by a 3D pseudo-spectral method in the rotating coordinate system. We use the FF+AE dipole plus off-centred quadrupole fields with minimum free parameters to reproduce two hotspot configurations found by the NICER observations. The X-ray and $\gamma$-ray emission from PSR J0030+0451 are simultaneously computed by using a ray-tracing method and a particle trajectory method. The modelled X-ray and $\gamma$-ray emission is then directly compared with those of PSR J0030+0451 from the NICER and Fermi observations. Our results can well reproduce the observed trends of the NICER X-ray and Fermi $\gamma$-ray emission for PSR J0030+0451.
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https://arxiv.org/abs/2601.07491
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Academic Papers
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9017e3be1e1e0be91415ddd90d168836e6174089ef42a8762d560df739f9c11c
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2026-01-13T00:00:00-05:00
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High-resolution simulations of non-thermal emission from LS 5039
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arXiv:2601.07501v1 Announce Type: new Abstract: In a previous study, we investigated the relativistic wind dynamics in the LS 5039 system. In this work, we analyse energetic-particle transport within this modelling context, where we simulate the high-energy particle distribution and ensuing emission of non-thermal radiation. From these high-resolution simulations, we compute the non-thermal emission from this system and compare it to corresponding observations. We modelled the LS 5039 system assuming a wind-driven scenario. Our numerical model uses a joint simulation of the dynamical wind interaction together with the transport of energetic leptons from the shocked pulsar wind. We computed the non-thermal emission from this system in a post-processing step from the resulting distribution of energetic leptons. In this computation, we took into account the synchrotron and inverse Compton emission, relativistic beaming, and {\gamma}{\gamma}-absorption in the stellar radiation field. We investigated the dynamical variation of the energetic particle spectra on both orbital and on short timescales. Our model successfully reproduces many of the spectral features of LS 5039. We also find a better correspondence between our predicted orbital light curves and the corresponding observations in soft x-rays, low-energy, and high-energy gamma rays than in our previous modelling efforts. We find that our high-resolution and large-scale simulations can successfully capture the relevant parts of the wind-collision region that are related to particle acceleration and emission of non-thermal radiation. The quality of the fit strengthens the wind-driven assumption underlying our model. Desirable extensions for the future include a dynamical magnetic-field model for the synchrotron regime, a revision of our injection parameters, and a consideration of an additional hadronic component that could explain recent observations in the 100~TeV regime.
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https://arxiv.org/abs/2601.07501
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Academic Papers
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b414c54d472c8403effe66336ca109f8e46ada441da7cf3d312f0c428e4d7fae
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2026-01-13T00:00:00-05:00
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Revealing the diversity of Type IIn supernova progenitors through their environments
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arXiv:2601.07542v1 Announce Type: new Abstract: Type IIn supernovae (SNe IIn) are hydrogen-rich explosions embedded in dense circumstellar medium (CSM), which gives rise to their characteristic narrow hydrogen emission lines. The nature of their progenitors and pre-explosion mass loss remains, however, poorly understood. Using high-resolution Hubble Space Telescope (HST) imaging, we analyze the local stellar environments of a volume-limited sample (z < 0.02) of 31 SNe IIn. The environments of SNe IIn are found to be very diverse; the SN could reside within a star-forming region (Class 1), outside a star-forming region (Class 2), or in much older environments without any obvious signs of star formation (Class 3). The bright SNe IIn (Mpeak < -19.5 mag) predominantly occur in Class 1 environments, indicative of very massive progenitors, while the faint SNe IIn (Mpeak < -15.5 mag) are associated with Classes 2 and 3 environments, suggesting the least massive progenitors. Meanwhile, normal SNe IIn with -19.5 < Mpeak < -15.5 mag occur in all three types of environments, suggesting a diversity in their progenitor mass, lifetime, and evolutionary pathways. Moreover, the directly detected SN IIn progenitors are systematically brighter and/or bluer than the youngest stellar populations in their environments, suggesting that they were either in a non-quiescent state when observed or had experienced binary interactions. These results point to a significantly diverse origin for progenitors of SNe IIn, spanning a wide range of masses, evolutionary stages, and potential binary interaction histories.
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https://arxiv.org/abs/2601.07542
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Academic Papers
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88add4fb7feaedb197f33254a92259280c27aac4a503823d24d0d62c134b85dd
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2026-01-13T00:00:00-05:00
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CASCO: Cosmological and AStrophysical parameters from Cosmological simulations and Observations IV. Testing warm dark matter cosmologies with galaxy scaling relations: A joint simulation-observation study using DREAMS simulations
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arXiv:2601.07543v1 Announce Type: new Abstract: Small-scale discrepancies in the standard Lambda cold dark matter paradigm have motivated the exploration of alternative dark matter (DM) models, such as warm dark matter (WDM). We investigate the constraining power of galaxy scaling relations on cosmological, astrophysical, and WDM parameters through a joint analysis of hydrodynamic simulations and observational data. Our study is based on the DREAMS project and combines large-volume uniform-box simulations with high-resolution Milky Way zoom-in runs in a $\Lambda$WDM cosmology. To ensure consistency between the different simulation sets, we apply calibrations to account for resolution effects, allowing us to exploit the complementary strengths of the two suites. We compare simulated relations, including stellar size, DM mass and fraction within the stellar half-mass radius, and the total-to-stellar mass ratio, with two complementary galaxy samples: the SPARC catalog of nearby spirals and the LVDB catalog of dwarf galaxies in the Local Volume. Using a bootstrap-based fitting procedure, we show that key cosmological parameters ($\Omega_m$, $\sigma_8$) and supernova feedback strength can be recovered with good accuracy, particularly from the uniform-box simulations. While the WDM particle mass remains unconstrained, the zoom-in simulations reveal subtle WDM-induced trends at low stellar masses in both the DM mass and total-to-stellar mass ratio. We also find that the galaxy stellar mass function exhibits a measurable dependence on the WDM particle mass below log10(M_*/Msun) <~ 8, which appears separable from the impact of feedback, suggesting it as a promising complementary probe. Our results highlight the importance of combining multi-resolution simulations with diverse observational datasets to jointly constrain baryonic processes and DM properties.
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https://arxiv.org/abs/2601.07543
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Academic Papers
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ba6b5789f4c5f279846f6faa003f85ba207c76077d9e7e8e723e45b327cbfa09
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2026-01-13T00:00:00-05:00
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Isochrone Fitting of Galactic Globular Clusters -- VII. NGC\,1904 (M79), NGC\,4372, and revision of NGC\,288, NGC\,362, NGC\,5904 (M5), NGC\,6205 (M13), and NGC\,6218 (M12)
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arXiv:2601.07555v1 Announce Type: new Abstract: We estimate key parameters for the Galactic globular clusters NGC1904 and NGC4372 and update the parameters for NGC288, NGC362, NGC5904, NGC6205, and NGC6218, which were analysed in our previous papers. We fit various colour--magnitude diagrams (CMDs) of the clusters using isochrones from the DSED and BaSTI. The CMDs are constructed from data sets provided by the HST, Gaia, SMSS, a large compilation of Stetson, and other sources, using multiple filters for each cluster. Our cross-identification of almost all the data sets with those from Gaia or HST allows us to use their astrometry to precisely select cluster members in all the data sets. We obtain the following estimates, along with their total uncertainties, for NGC288, NGC362, NGC1904, NGC4372, NGC5904, NGC6205 and NGC6218, respectively: metallicities [Fe/H]$=-1.28$, $-1.26$, $-1.64$, $-2.28$, $-1.33$, $-1.56$, and $-1.27$ dex; ages $12.94$, $10.33$, $13.16$, $12.81$, $11.53$, $12.75$, and $13.03$ Gyr; distances $8.83$, $9.00$, $12.66$, $5.17$, $7.24$, $7.39$, and $4.92$ kpc; reddenings $E(B-V)=0.022$, $0.029$, $0.031$, $0.545$, $0.045$, $0.024$, and $0.210$ mag; extinctions $Av=0.09$, $0.09$, $0.11$, $1.58$, $0.13$, $0.09$, and $0.67$ mag; and extinction-to-reddening ratio $Rv=3.9$, $3.0$, $3.8$, $2.9$, $2.9$, $3.6$, and $3.2$. We confirm that the differences in horizontal branch morphology among the 16 Galactic globular clusters analysed in our studies can be explained by variations in their metallicity, age, mass-loss efficiency, and the loss of low-mass members during cluster evolution. Accordingly, most clusters indicate a relatively high mass-loss efficiency, consistent with the Reimers mass-loss law with $\eta>0.3$.
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https://arxiv.org/abs/2601.07555
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Academic Papers
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748244347a1a963367c9246194d0d0c0992ed03ec15892b725cbe17d321c2329
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2026-01-13T00:00:00-05:00
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Uniform models of neutron and quark (strange) stars in General Relativity
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arXiv:2601.07560v1 Announce Type: new Abstract: Models of neutron and strange stars are considered in the approximation of a uniform density distribution. A universal algebraic equation, valid for any equation of state, is used to find the approximate mass of a star of a given density without resorting to the integration of differential equations. Equations of state for neutron stars had been taken for degenerate neutron gas and for more realistic ones, used by Bethe, Malone, Johnson (1975). Models of homogeneous strange stars for the equation of state in the "quark bag model" have a simple analytical solution. The solutions presented in the paper for various equations of state differ from the exact solutions obtained by the numerical integration of differential equations by at most $ \sim 20 \%$. The formation of strange stars is examined as a function of the deconfinement boundary (DB), at which quarks become deconfined. Existing experimental data indicate that matter reaches very high densities in the vicinity of the DB. This imposes strong constraints on the maximum mass of strange stars and prohibits their formation at the final stages of stellar evolution, because the limiting mass of neutron stars is substantially higher and corresponds to considerably lower matter densities.
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https://arxiv.org/abs/2601.07560
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Academic Papers
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fabcdf40b9846434135877610c606be8da5398606d2c9cfcd5eb00dffc6dc09d
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2026-01-13T00:00:00-05:00
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Cosmic rays, gamma rays and neutrinos from discrete black hole X-ray binary ejecta
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arXiv:2601.07589v1 Announce Type: new Abstract: The origin of cosmic rays from outside the Solar system are unknown, as they are deflected by the interstellar magnetic field. Supernova remnants are the main candidate for cosmic rays up to PeV energies but due to lack of evidence, they cannot be concluded as the sources of the most energetic Galactic CRs. We investigate discrete ejecta produced in state transitions of black hole X-ray binary systems as a potential source of cosmic rays, motivated by recent $>100$ TeV $\gamma$-ray detections by LHAASO. Starting from MAXI J1820+070, we examine the multi-wavelength observations and find that efficient particle acceleration may take place (i.e. into a robust power-law), up to $\sim2\times 10^{16}\mu^{-1/2}$ eV, where $\mu$ is the ratio of particle energy to magnetic energy. From these calculations, we estimate the global contribution of ejecta to the entire Galactic spectrum to be $\sim1\%$, with the cosmic ray contribution rising to $\sim5\%$ at PeV energies, assuming roughly equal energy in non-thermal protons, non-thermal electrons and magnetic fields. In addition, we calculate associated $\gamma$-ray and neutrino spectra of the MAXI J1820+070 ejecta to investigate new detection methods with CTAO, which provide strong constraints on initial ejecta size of order $10^7$ Schwarzschild radii ($10^{-5}$ pc) assuming a period of adiabatic expansion.
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https://arxiv.org/abs/2601.07589
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Academic Papers
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