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type ia supernovae (sne ia) play a prominent role in understanding the evolution of the universe. they are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs (co wds) in binaries, although the mass donors of the accreting wds are still not well determined. in this article, i review recent studies on mass-accreting wds, including h- and he-accreting wds. i also review currently most studied progenitor models of sne ia, i.e., the single-degenerate model (including the wd+ms channel, the wd+rg channel and the wd+he star channel), the double-degenerate model (including the violent merger scenario) and the sub-chandrasekhar mass model. recent progress on these progenitor models is discussed, including the initial parameter space for producing sne ia, the binary evolutionary paths to sne ia, the progenitor candidates for sne ia, the possible surviving companion stars of sne ia, some observational constraints, etc. some other potential progenitor models of sne ia are also summarized, including the hybrid cone wd model, the core-degenerate model, the double wd collision model, the spin-up/spin-down model and the model of wds near black holes. to date, it seems that two or more progenitor models are needed to explain the observed diversity among sne ia. | mass-accreting white dwarfs and type ia supernovae |
we present results from simulations of core-collapse supernovae in flash using a newly implemented multidimensional neutrino transport scheme and a newly implemented general relativistic (gr) treatment of gravity. we use a two-moment method with an analytic closure (so-called m1 transport) for the neutrino transport. this transport is multienergy, multispecies, velocity dependent, and truly multidimensional, i.e., we do not assume the commonly used “ray-by-ray” approximation. our gr gravity is implemented in our newtonian hydrodynamics simulations via an effective relativistic potential that closely reproduces the gr structure of neutron stars and has been shown to match gr simulations of core collapse quite well. in axisymmetry, we simulate core-collapse supernovae with four different progenitor models in both newtonian and gr gravity. we find that the more compact proto-neutron star structure realized in simulations with gr gravity gives higher neutrino luminosities and higher neutrino energies. these differences in turn give higher neutrino heating rates (upward of ∼20%-30% over the corresponding newtonian gravity simulations) that increase the efficacy of the neutrino mechanism. three of the four models successfully explode in the simulations assuming grep gravity. in our newtonian gravity simulations, two of the four models explode, but at times much later than observed in our gr gravity simulations. our results, in both newtonian and gr gravity, compare well with several other studies in the literature. these results conclusively show that the approximation of newtonian gravity for simulating the core-collapse supernova central engine is not acceptable. we also simulate four additional models in gr gravity to highlight the growing disparity between parameterized 1d models of core-collapse supernovae and the current generation of 2d models. | two-dimensional core-collapse supernova explosions aided by general relativity with multidimensional neutrino transport |
we present the results from a search for gravitational-wave transients associated with core-collapse supernovae observed within a source distance of approximately 20 mpc during the first and second observing runs of advanced ligo and advanced virgo. no significant gravitational-wave candidate was detected. we report the detection efficiencies as a function of the distance for waveforms derived from multidimensional numerical simulations and phenomenological extreme emission models. the sources with neutrino-driven explosions are detectable at the distances approaching 5 kpc, and for magnetorotationally driven explosions the distances are up to 54 kpc. however, waveforms for extreme emission models are detectable up to 28 mpc. for the first time, the gravitational-wave data enabled us to exclude part of the parameter spaces of two extreme emission models with confidence up to 83%, limited by coincident data coverage. besides, using ad hoc harmonic signals windowed with gaussian envelopes, we constrained the gravitational-wave energy emitted during core collapse at the levels of 4.27 ×10-4 m⊙c2 and 1.28 ×10-1 m⊙c2 for emissions at 235 and 1304 hz, respectively. these constraints are 2 orders of magnitude more stringent than previously derived in the corresponding analysis using initial ligo, initial virgo, and geo 600 data. | optically targeted search for gravitational waves emitted by core-collapse supernovae during the first and second observing runs of advanced ligo and advanced virgo |
context. the efficiency of the different processes responsible for the evolution of interstellar dust on the scale of a galaxy are, to date, very uncertain, spanning several orders of magnitude in the literature. yet, precise knowledge of the grain properties is key to addressing numerous open questions about the physics of the interstellar medium and galaxy evolution.aims: this article presents an empirical statistical study, aimed at quantifying the timescales of the main cosmic dust evolution processes as a function of the global properties of a galaxy.methods: we modeled a sample of ≃800 nearby galaxies, spanning a wide range of metallicities, gas fractions, specific star formation rates, and hubble stages. we derived the dust properties of each object from its spectral energy distribution. through an additional level of analysis, we inferred the timescales of dust condensation in core-collapse supernova ejecta, grain growth in cold clouds, and dust destruction by shock waves. throughout this paper, we have adopted a hierarchical bayesian approach, resulting in a single large probability distribution of all the parameters of all the galaxies, to ensure the most rigorous interpretation of our data.results: we confirm the drastic evolution with metallicity of the dust-to-metal mass ratio (by two orders of magnitude), found by previous studies. we show that dust production by core-collapse supernovae is efficient only at very low metallicity, a single supernova producing on average less than ≃0.03 m⊙/sn of dust. our data indicate that grain growth is the dominant formation mechanism at metallicity above ≃1/5 solar, with a grain growth timescale shorter than ≃50 myr at solar metallicity. shock destruction is relatively efficient, a single supernova clearing dust on average in at least ≃1200 m⊙/sn of gas. these results are robust when assuming different stellar initial mass functions. in addition, we show that early-type galaxies are outliers in several scaling relations. this feature could result from grain thermal sputtering in hot x-ray emitting gas, which is a hypothesis supported by a negative correlation between the dust-to-stellar mass ratio and the x-ray photon rate per grain. finally, we confirm the well-known evolution of the aromatic-feature-emitting grain mass fraction as a function of metallicity and interstellar radiation field intensity. our data indicate that the relation with metallicity is significantly stronger.conclusions: our results provide valuable constraints for simulations of galaxies. they imply that grain growth is the likely dust production mechanism in dusty high-redshift objects. we also emphasize the determinant role of local, low metallicity systems in order to address these questions. table h.1 is only available at the cds via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/649/a18 dustpedia is a collaborative focused research project supported by the european union under the seventh framework programme (2007- 2013) call (proposal no. 606847, pi j. i. davies). the data used in this work are publicly available at http://dustpedia.astro.noa.gr | a nearby galaxy perspective on dust evolution. scaling relations and constraints on the dust build-up in galaxies with the dustpedia and dgs samples |
we present observations of sn 2021csp, a unique supernova (sn) which displays evidence for interaction with h- and he- poor circumstellar material (csm) at early times. using high-cadence spectroscopy taken over the first week after explosion, we show that the spectra of sn 2021csp are dominated by c iii lines with a velocity of 1800 km s$^{-1}$. we associate this emission with csm lost by the progenitor prior to explosion. subsequently, the sn displays narrow he lines before metamorphosing into a broad-lined type ic sn. we model the bolometric light curve of sn 2021csp, and show that it is consistent with the energetic ($4\times10^{51}$ erg) explosion of a stripped star, producing 0.4 m$_\odot$ of 56ni within a $\sim$1 m$_\odot$ shell of csm extending out to 400 r$_\odot$. | sn 2021csp -- the explosion of a stripped envelope star within a h and he-poor circumstellar medium |
non-standard neutrino interactions with a massive boson can produce the bosons in the core of core-collapse supernovae (sne). after the emission of the bosons from the sn core, their subsequent decays into neutrinos can modify the sn neutrino flux. we show future observations of neutrinos from a next galactic sn in super-kamiokande (sk) and hyper-kamiokande (hk) can probe flavor-universal non-standard neutrino couplings to a light boson, improving the previous limit from the sn 1987a neutrino burst by several orders of magnitude. we also discuss sensitivity of the flavor-universal non-standard neutrino interactions in future observations of diffuse neutrinos from all the past sne, known as the diffuse supernova neutrino background (dsnb). according to our analysis, observations of the dsnb in hk, juno and dune experiments can probe such couplings by a factor of ∼ 2 beyond the sn 1987a constraint. however, our result is also subject to a large uncertainty concerning the precise estimation of the dsnb. | probing non-standard neutrino interactions with a light boson from next galactic and diffuse supernova neutrinos |
a novel analysis is performed, incorporating time-of-flight (tof) information to study the interactions of dark matter (dm) with standard model particles. after supernova (sn) explosions, dm with mass mχ≲o (mev ) in the halo can be boosted by sn neutrinos (sn ν ) to relativistic speed. the sn ν boosted dm (bdm) arrives on earth with tof which depends only on mχ and is independent of the cross section. these bdms can interact with detector targets in low-background experiments and manifest as afterglow events after the arrival of sn ν . the characteristic tof spectra of the bdm events can lead to large background suppression and unique determination of mχ. new cross section constraints on √{σχ eσχ ν } are derived from sn1987a in the large magellanic cloud with data from the kamiokande and super-kamiokande experiments. potential sensitivities for the next galactic sn with hyper-kamiokande are projected. this analysis extends the existing bounds on √{σχ eσχ ν } over a broad range of rχ=σχ ν/σχ e. in particular, the improvement is by 1-3 orders of magnitude for mχ<o (100 kev ) for σχ e∼σχ ν. prospects of exploiting tof information in other astrophysical systems to probe exotic physics with other dm candidates are discussed. | searching for afterglow: light dark matter boosted by supernova neutrinos |
the kbc void is a local underdensity with the observed relative density contrast δ ≡ 1 - ρ/ρ0 = 0.46 ± 0.06 between 40 and 300 mpc around the local group. if mass is conserved in the universe, such a void could explain the 5.3σ hubble tension. however, the mxxl simulation shows that the kbc void causes 6.04σ tension with standard cosmology (λcdm). combined with the hubble tension, λcdm is ruled out at 7.09σ confidence. consequently, the density and velocity distribution on gpc scales suggest a long-range modification to gravity. in this context, we consider a cosmological mond model supplemented with $11 \, \rm {ev}/c^{2}$ sterile neutrinos. we explain why this νhdm model has a nearly standard expansion history, primordial abundances of light elements, and cosmic microwave background (cmb) anisotropies. in mond, structure growth is self-regulated by external fields from surrounding structures. we constrain our model parameters with the kbc void density profile, the local hubble and deceleration parameters derived jointly from supernovae at redshifts 0.023-0.15, time delays in strong lensing systems, and the local group velocity relative to the cmb. our best-fitting model simultaneously explains these observables at the $1.14{{\ \rm per\ cent}}$ confidence level (2.53σ tension) if the void is embedded in a time-independent external field of ${0.055 \, a_{_0}}$ . thus, we show for the first time that the kbc void can naturally resolve the hubble tension in milgromian dynamics. given the many successful a priori mond predictions on galaxy scales that are difficult to reconcile with λcdm, milgromian dynamics supplemented by $11 \, \rm {ev}/c^{2}$ sterile neutrinos may provide a more holistic explanation for astronomical observations across all scales. | the kbc void and hubble tension contradict λcdm on a gpc scale - milgromian dynamics as a possible solution |
we investigate the explosion of stars with zero-age main-sequence masses between 20 and 35 m⊙ and varying degrees of rotation and magnetic fields including ones commonly considered progenitors of gamma-ray bursts (grbs). the simulations, combining special relativistic magnetohydrodynamics, a general relativistic approximate gravitational potential, and two-moment neutrino transport, demonstrate the viability of different scenarios for the post-bounce evolution. having formed a highly massive proto-neutron star (pns), several models launch successful explosions, either by the standard supernova mechanism based on neutrino heating and hydrodynamic instabilities or by magnetorotational processes. it is, however, quite common for the pns to collapse to a black hole (bh) within a few seconds. others might produce proto-magnetar-driven explosions. we explore several ways to describe the different explosion mechanisms. the competition between the time-scales for advection of gas through the gain layer and heating by neutrinos provides an approximate explanation for models with insignificant magnetic fields. the fidelity of this explosion criterion in the case of rapid rotation can be improved by accounting for the strong deviations from spherical symmetry and mixing between pole and equator. we furthermore study an alternative description including the ram pressure of the gas falling through the shock. magnetically driven explosions tend to arise from a strongly magnetized region around the polar axis. in these cases, the onset of the explosion corresponds to the equality between the advection time-scale and the time-scale for the propagation of alfvén waves through the gain layer. | magnetorotational core collapse of possible grb progenitors - i. explosion mechanisms |
we investigated r-process nucleosynthesis in magneto-rotational supernovae, based on a new explosion mechanism induced by the magneto-rotational instability (mri). a series of axisymmetric magneto-hydrodynamical simulations with detailed microphysics including neutrino heating is performed, numerically resolving the mri. neutrino-heating dominated explosions, enhanced by magnetic fields, showed mildly neutron-rich ejecta producing nuclei up to a∼ 130 (i.e., the weak r-process), while explosion models with stronger magnetic fields reproduce a solar-like r-process pattern. more commonly seen abundance patterns in our models are in between the weak and regular r-process, producing lighter and intermediate-mass nuclei. these intermediate r-processes exhibit a variety of abundance distributions, compatible with several abundance patterns in r-process-enhanced metal-poor stars. the amount of eu ejecta ∼ {10}-5 {m}⊙in magnetically driven jets agrees with predicted values in the chemical evolution of early galaxies. in contrast, neutrino-heating dominated explosions have a significant amount of fe ({}56{{ni}}) and zn, comparable to regular supernovae and hypernovae, respectively. these results indicate magneto-rotational supernovae can produce a wide range of heavy nuclei from iron-group to r-process elements, depending on the explosion dynamics. | the intermediate r-process in core-collapse supernovae driven by the magneto-rotational instability |
we present a new approach to understand the landscape of supernova explosion energies, ejected nickel masses, and neutron star birth masses. in contrast to other recent parametric approaches, our model predicts the properties of neutrino-driven explosions based on the pre-collapse stellar structure without the need for hydrodynamic simulations. the model is based on physically motivated scaling laws and simple differential equations describing the shock propagation, the contraction of the neutron star, the neutrino emission, the heating conditions, and the explosion energetics. using model parameters compatible with multi-d simulations and a fine grid of thousands of supernova progenitors, we obtain a variegated landscape of neutron star and black hole formation similar to other parametrized approaches and find good agreement with semi-empirical measures for the `explodability' of massive stars. our predicted explosion properties largely conform to observed correlations between the nickel mass and explosion energy. accounting for the coexistence of outflows and downflows during the explosion phase, we naturally obtain a positive correlation between explosion energy and ejecta mass. these correlations are relatively robust against parameter variations, but our results suggest that there is considerable leeway in parametric models to widen or narrow the mass ranges for black hole and neutron star formation and to scale explosion energies up or down. our model is currently limited to an all-or-nothing treatment of fallback and there remain some minor discrepancies between model predictions and observational constraints. | a simple approach to the supernova progenitor-explosion connection |
several stellar systems (white dwarfs, red giants, horizontal branch stars and possibly the neutron star in the supernova remnant cassiopeia a) show a mild preference for a non-standard cooling mechanism when compared with theoretical models. this exotic cooling could be provided by weakly interacting slim particles (wisps), produced in the hot cores and abandoning the star unimpeded, contributing directly to the energy loss. taken individually, these excesses do not show a strong statistical weight. however, if one mechanism could consistently explain several of them, the hint could be significant. we analyze the hints in terms of neutrino anomalous magnetic moments, minicharged particles, hidden photons and axion-like particles (alps). among them, the alp or a massless hp represent the best solution. interestingly, the hinted alp parameter space is accessible to the next generation proposed alp searches, such as alps ii and iaxo and the massless hp requires a multi tev energy scale of new physics that might be accessible at the lhc. | cool wisps for stellar cooling excesses |
the coherent collaboration's primary objective is to measure coherent elastic neutrino-nucleus scattering (cevns) using the unique, high-quality source of tens-of-mev neutrinos provided by the spallation neutron source (sns) at oak ridge national laboratory (ornl). in spite of its large cross section, the cevns process has never been observed, due to tiny energies of the resulting nuclear recoils which are out of reach for standard neutrino detectors. the measurement of cevns has now become feasible, thanks to the development of ultra-sensitive technology for rare decay and weakly-interacting massive particle (dark matter) searches. the cevns cross section is cleanly predicted in the standard model; hence its measurement provides a standard model test. it is relevant for supernova physics and supernova-neutrino detection, and enables validation of dark-matter detector background and detector-response models. in the long term, precision measurement of cevns will address questions of nuclear structure. coherent will deploy multiple detector technologies in a phased approach: a 14-kg csi[na] scintillating crystal, 15 kg of p-type point-contact germanium detectors, and 100 kg of liquid xenon in a two-phase time projection chamber. following an extensive background measurement campaign, a location in the sns basement has proven to be neutron-quiet and suitable for deployment of the coherent detector suite. the simultaneous deployment of the three coherent detector subsystems will test the $n^2$ dependence of the cross section and ensure an unambiguous discovery of cevns. this document describes concisely the coherent physics motivations, sensitivity and plans for measurements at the sns to be accomplished on a four-year timescale. | the coherent experiment at the spallation neutron source |
we present x-ray and radio observations of the fast blue optical transient crts-css161010 j045834-081803 (css161010 hereafter) at t = 69-531 days. css161010 shows luminous x-ray (lx ∼ 5 × 1039 erg s-1) and radio (lν ∼ 1029 erg s-1 hz-1) emission. the radio emission peaked at ∼100 days post-transient explosion and rapidly decayed. we interpret these observations in the context of synchrotron emission from an expanding blast wave. css161010 launched a mildly relativistic outflow with velocity γβc ≥ 0.55c at ∼100 days. this is faster than the non-relativistic at 2018cow (γβc ∼ 0.1c) and closer to ztf18abvkwla (γβc ≥ 0.3c at 63 days). the inferred initial kinetic energy of css161010 (ek ≳ 1051 erg) is comparable to that of long gamma-ray bursts, but the ejecta mass that is coupled to the mildly relativistic outflow is significantly larger ( $\sim 0.01\mbox{--}0.1\,{m}_{\odot }$ ). this is consistent with the lack of observed γ-rays. the luminous x-rays were produced by a different emission component to the synchrotron radio emission. css161010 is located at ∼150 mpc in a dwarf galaxy with stellar mass m* ∼ 107 m⊙ and specific star formation rate ssfr ∼ 0.3 gyr-1. this mass is among the lowest inferred for host galaxies of explosive transients from massive stars. our observations of css161010 are consistent with an engine-driven aspherical explosion from a rare evolutionary path of a h-rich stellar progenitor, but we cannot rule out a stellar tidal disruption event on a centrally located intermediate-mass black hole. regardless of the physical mechanism, css161010 establishes the existence of a new class of rare (rate < 0.4% of the local core-collapse supernova rate) h-rich transients that can launch mildly relativistic outflows. | a mildly relativistic outflow from the energetic, fast-rising blue optical transient css161010 in a dwarf galaxy |
we present the nucleosynthesis of magneto-rotational supernovae (mr-sne) including neutrino-driven and magneto-rotational-driven ejecta based, for the first time, on 2d simulations with accurate neutrino transport. the models analysed here have different rotation and magnetic fields, allowing us to explore the impact of these two key ingredients. the accurate neutrino transport of the simulations is critical to analyse the slightly neutron-rich and proton-rich ejecta that are similar to the, also neutrino-driven, ejecta in standard supernovae. in the model with strong magnetic field, the r-process produces heavy elements up to the third r-process peak (a ∼ 195), in agreement with previous works. this model presents a jet-like explosion with proton-rich jets surrounded by neutron-rich material where the r-process occurs. we have estimated a lower limit for 56ni of $2.5\times 10^{-2} \, \mathrm{m}_\odot$ , which is still well below the expected hypernova value. longer simulations including the accretion disc evolution are required to get a final prediction. in addition, we have found that the late evolution is critical in a model with weak magnetic field in which late-ejected neutron-rich matter produces elements up to the second r-process peak. even if we cannot yet provide conclusions for hypernova nucleosynthesis, our results agree with observations of old stars and radioactive isotopes in supernova remnants. this makes mr-sne a good additional scenario to neutron star mergers for the synthesis of heavy elements and brings us closer to understand their origin and the role of mr-sne in the early galaxy nucleosynthesis. | nucleosynthesis in magneto-rotational supernovae |
the china jinping underground laboratory (cjpl), which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. with two detectors and a total fiducial mass of 2000 tons for solar neutrino physics (equivalently, 3000 tons for geo-neutrino and supernova neutrino physics), the jinping neutrino experiment will have the potential to identify the neutrinos from the cno fusion cycles of the sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the th/u ratio. these goals can be fulfilled with mature existing techniques. efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the jinping discovery potential in the study of solar neutrinos, geo-neutrinos, supernova neutrinos, and dark matter. supported by the national natural science foundation of china (11235006, 11475093, 11135009, 11375065, 11505301, and 11620101004), the tsinghua university initiative scientific research program (20121088035, 20131089288, and 20151080432), the key laboratory of particle & radiation imaging (tsinghua university), the cas center for excellence in particle physics (ccepp), u.s. national science foundation grant phy-1404311 (beacom), and u.s. department of energy under contract de-ac02-98ch10886 (yeh). | physics prospects of the jinping neutrino experiment |
the neutrino-heated "gain layer" immediately behind the stalled shock in a core-collapse supernova is unstable to high-reynolds-number turbulent convection. we carry out and analyze a new set of 19 high-resolution three-dimensional (3d) simulations with a three-species neutrino leakage/heating scheme and compare with spherically symmetric (one-dimensional, 1d) and axisymmetric (two-dimensional, 2d) simulations carried out with the same methods. we study the postbounce supernova evolution in a 15 m ⊙ progenitor star and vary the local neutrino heating rate, the magnitude and spatial dependence of asphericity from convective burning in the si/o shell, and spatial resolution. our simulations suggest that there is a direct correlation between the strength of turbulence in the gain layer and the susceptibility to explosion. 2d and 3d simulations explode at much lower neutrino heating rates than 1d simulations. this is commonly explained by the fact that nonradial dynamics allows accreting material to stay longer in the gain layer. we show that this explanation is incomplete. our results indicate that the effective turbulent ram pressure exerted on the shock plays a crucial role by allowing multi-dimensional models to explode at a lower postshock thermal pressure and thus with less neutrino heating than 1d models. we connect the turbulent ram pressure with turbulent energy at large scales and in this way explain why 2d simulations are erroneously exploding more easily than 3d simulations. | the role of turbulence in neutrino-driven core-collapse supernova explosions |
many statistical models in cosmology can be simulated forwards but have intractable likelihood functions. likelihood-free inference methods allow us to perform bayesian inference from these models using only forward simulations, free from any likelihood assumptions or approximations. likelihood-free inference generically involves simulating mock data and comparing to the observed data; this comparison in data space suffers from the curse of dimensionality and requires compression of the data to a small number of summary statistics to be tractable. in this paper, we use massive asymptotically optimal data compression to reduce the dimensionality of the data space to just one number per parameter, providing a natural and optimal framework for summary statistic choice for likelihood-free inference. secondly, we present the first cosmological application of density estimation likelihood-free inference (delfi), which learns a parametrized model for joint distribution of data and parameters, yielding both the parameter posterior and the model evidence. this approach is conceptually simple, requires less tuning than traditional approximate bayesian computation approaches to likelihood-free inference and can give high-fidelity posteriors from orders of magnitude fewer forward simulations. as an additional bonus, it enables parameter inference and bayesian model comparison simultaneously. we demonstrate delfi with massive data compression on an analysis of the joint light-curve analysis supernova data, as a simple validation case study. we show that high-fidelity posterior inference is possible for full-scale cosmological data analyses with as few as ∼104 simulations, with substantial scope for further improvement, demonstrating the scalability of likelihood-free inference to large and complex cosmological data sets. | massive optimal data compression and density estimation for scalable, likelihood-free inference in cosmology |
presently, a >3σ tension exists between values of the hubble constant h0 derived from analysis of fluctuations in the cosmic microwave background by planck, and local measurements of the expansion using calibrators of type ia supernovae (sne ia). we perform a blinded re-analysis of riess et al. (2011) to measure h0 from low-redshift sne ia, calibrated by cepheid variables and geometric distances including to ngc 4258. this paper is a demonstration of techniques to be applied to the riess et al. (2016) data. our end-to-end analysis starts from available harvard -smithsonian center for astrophysics (cfa3) and lick observatory supernova search (loss) photometries, providing an independent validation of riess et al. (2011). we obscure the value of h0 throughout our analysis and the first stage of the referee process, because calibration of sne ia requires a series of often subtle choices, and the potential for results to be affected by human bias is significant. our analysis departs from that of riess et al. (2011) by incorporating the covariance matrix method adopted in supernova legacy survey and joint lightcurve analysis to quantify sn ia systematics, and by including a simultaneous fit of all sn ia and cepheid data. we find h_0 = 72.5 ± 3.1 ({stat}) ± 0.77 ({sys}) km s-1 mpc-1with a three-galaxy (ngc 4258+lmc+mw) anchor. the relative uncertainties are 4.3 per cent statistical, 1.1 per cent systematic, and 4.4 per cent total, larger than in riess et al. (2011) (3.3 per cent total) and the efstathiou (2014) re-analysis (3.4 per cent total). our error budget for h0 is dominated by statistical errors due to the small size of the sn sample, whilst the systematic contribution is dominated by variation in the cepheid fits, and for the sne ia, uncertainties in the host galaxy mass dependence and malmquist bias. | a blinded determination of h0 from low-redshift type ia supernovae, calibrated by cepheid variables |
narrow transient emission lines (flash-ionization features) in early supernova (sn) spectra trace the presence of circumstellar material (csm) around the massive progenitor stars of core-collapse sne. the lines disappear within days after the sn explosion, suggesting that this material is spatially confined, and originates from enhanced mass loss shortly (months to a few years) prior to the explosion. we performed a systematic survey of h-rich (type ii) sne discovered within less than 2 days from the explosion during the first phase of the zwicky transient facility survey (2018-2020), finding 30 events for which a first spectrum was obtained within <2 days from the explosion. the measured fraction of events showing flash-ionization features (>36% at the 95% confidence level) confirms that elevated mass loss in massive stars prior to sn explosion is common. we find that sne ii showing flash-ionization features are not significantly brighter, nor bluer, nor more slowly rising than those without. this implies that csm interaction does not contribute significantly to their early continuum emission, and that the csm is likely optically thin. we measured the persistence duration of flash-ionization emission and find that most sne show flash features for ≈5 days. rarer events, with persistence timescales >10 days, are brighter and rise longer, suggesting these may be intermediate between regular sne ii and strongly interacting sne iin. | the prevalence and influence of circumstellar material around hydrogen-rich supernova progenitors |
radiative feedback (rfb) from stars plays a key role in galaxies, but remains poorly understood. we explore this using high-resolution, multifrequency radiation-hydrodynamics (rhd) simulations from the feedback in realistic environments (fire) project. we study ultrafaint dwarf through milky way mass scales, including h+he photoionization; photoelectric, lyman werner, compton, and dust heating; and single+multiple scattering radiation pressure (rp). we compare distinct numerical algorithms: ray-based lebron (exact when optically thin) and moments-based m1 (exact when optically thick). the most important rfb channels on galaxy scales are photoionization heating and single-scattering rp: in all galaxies, most ionizing/far-uv luminosity (∼1/2 of lifetime-integrated bolometric) is absorbed. in dwarfs, the most important effect is photoionization heating from the uv background suppressing accretion. in mw-mass galaxies, metagalactic backgrounds have negligible effects; but local photoionization and single-scattering rp contribute to regulating the galactic star formation efficiency and lowering central densities. without some rfb (or other 'rapid' fb), resolved gmcs convert too-efficiently into stars, making galaxies dominated by hyperdense, bound star clusters. this makes star formation more violent and 'bursty' when sne explode in these hyperclustered objects: thus, including rfb 'smoothes' sfhs. these conclusions are robust to rhd methods, but m1 produces somewhat stronger effects. like in previous fire simulations, ir multiple-scattering is rare (negligible in dwarfs, ∼ 10 per cent of rp in massive galaxies): absorption occurs primarily in 'normal' gmcs with av ∼ 1. | radiative stellar feedback in galaxy formation: methods and physics |
neutrinos are believed to have a key role in the explosion mechanism of core-collapse supernovae as they carry most of the energy released by the gravitational collapse of a massive star. if their flavor is converted fast inside the neutrino sphere, the supernova explosion may be influenced. this paper is reporting the results of the extended work of our previous paper. we perform a thorough survey of the electron lepton number (eln) crossing in one of our self-consistent, realistic boltzmann simulations in two spatial dimensions under axisymmetry for the existence of the crossings between νe and ν¯e angular distributions, or the eln crossing. we report for the first time the positive detections deep inside the core of the massive star in the vicinity of neutrino sphere at r ≈16 - 21 km . we find that low values of the electron fraction ye produced by convective motions together with the appearance of light elements are critically important to give rise to the eln crossing by enhancing the chemical potential difference between proton and neutron, and hence by mitigating the fermi-degeneracy of νe. since the region of positive detection are sustained and, in fact, expanding with time, it may have an impact on the explosion of core-collapse supernovae, observational neutrino astronomy, and nucleosynthesis of heavy nuclei. | fast collective neutrino oscillations inside the neutrino sphere in core-collapse supernovae |
if type ia supernovae (sne~ia) result from a white dwarf being ignited by roche lobe overflow from a nondegenerate companion, then as the supernova explosion runs into the companion star its ejecta will be shocked, causing an early blue excess in the lightcurve. a handful of these excesses have been found in single-object studies, but inferences about the population of sne~ia as a whole have been limited because of the rarity of multiwavelength followup within days of explosion. here we present a three-year investigation yielding an unbiased sample of nine nearby ($z<0.01$) sne~ia with exemplary early data. the data are truly multiwavelength, covering $ubvgri$ and swift bandpasses, and also early, with an average first epoch 16.0 days before maximum light. of the nine objects, three show early blue excesses. we do not find enough statistical evidence to reject the null hypothesis that sne~ia predominantly arise from roche-lobe-overflowing single-degenerate systems ($p=0.94$). when looking at the objects' colors, we find the objects are almost uniformly near-uv-blue, in contrast to earlier literature samples which found that only a third of sne~ia are near-uv-blue, and we find a seemingly continuous range of $b-v$ colors in the days after explosion, again in contrast with earlier claims in the literature. this study highlights the importance of early, truly multiwavelength, high-cadence data in determining the progenitor systems of sne~ia and in revealing their diverse early behavior. | early lightcurves of type ia supernovae are consistent with nondegenerate progenitor companions |
the angular momentum (am) content of massive stellar cores helps us to determine the natal spin rates of neutron stars and black holes. asteroseismic measurements of low-mass stars have proven that stellar cores rotate slower than predicted by most prior work, so revised models are necessary. in this work, we apply an updated am transport model based on the tayler instability to massive helium stars in close binaries, in which tidal spin-up can greatly increase the star's am. consistent with prior work, these stars can produce highly spinning black holes upon core-collapse if the orbital period is less than $p_{\rm orb} \lesssim \! 1 \, {\rm d}$. for neutron stars, we predict a strong correlation between the pre-explosion mass and the neutron star rotation rate, with millisecond periods ($p_{\rm ns} \lesssim 5 \, {\rm ms}$) only achievable for massive ($m \gtrsim 10 \, m_\odot$) helium stars in tight ($p_{\rm orb} \lesssim 1 \, {\rm d}$) binaries. finally, we discuss our models in relation to type ib/c supernovae, superluminous supernove, gamma-ray bursts, and ligo/virgo measurements of black hole spins. our models are roughly consistent with the rates and energetics of these phenomena, with the exception of broad-lined ic supernovae, whose high rates and ejecta energies are difficult to explain. | the spins of compact objects born from helium stars in binary systems |
in extreme astrophysical environments such as core-collapse supernovae and binary neutron star mergers, neutrinos play a major role in driving various dynamical and microphysical phenomena, such as baryonic matter outflows, the synthesis of heavy elements, and the supernova explosion mechanism itself. the interactions of neutrinos with matter in these environments are flavor-specific, which makes it of paramount importance to understand the flavor evolution of neutrinos. flavor evolution in these environments can be a highly nontrivial problem thanks to a multitude of collective effects in flavor space, arising due to neutrino-neutrino (ν -ν ) interactions in regions with high neutrino densities. a neutrino ensemble undergoing flavor oscillations under the influence of significant ν -ν interactions is somewhat analogous to a system of coupled spins with long-range interactions among themselves and with an external field (` long-range' in momentum-space in the case of neutrinos). as a result, it becomes pertinent to consider whether these interactions can give rise to significant quantum correlations among the interacting neutrinos, and whether these correlations have any consequences for the flavor evolution of the ensemble. in particular, one may seek to utilize concepts and tools from quantum information science and quantum computing to deepen our understanding of these phenomena. in this article, we attempt to summarize recent work in this field. furthermore, we also present some new results in a three-flavor setting, considering complex initial states. | quantum information and quantum simulation of neutrino physics |
we revise gamma-ray limits on axion-like particles (alps) emitted from supernova sn1987a based on solar maximum mission data. we improve and simplify the computation of the expected gamma-ray signal from alp decays, while also extending it to non-instantaneous alp emission. for the first time we make use of the temporal information in the data to update the associated alp-photon coupling limits. for alp decays, our updated likelihood only mildly affects the limit compared to previous works due to the absorption of gamma rays close to sn1987a. however, for alp conversions in the galactic magnetic field, temporal information improves the limit on the alp-photon coupling by a factor of 1.4. | updated constraints on axion-like particles from temporal information in supernova sn1987a gamma-ray data |
what is the origin of the oxygen we breathe, the hydrogen and oxygen (in form of water h2o) in rivers and oceans, the carbon in all organic compounds, the silicon in electronic hardware, the calcium in our bones, the iron in steel, silver and gold in jewels, the rare earths utilized, e.g. in magnets or lasers, lead or lithium in batteries, and also of naturally occurring uranium and plutonium? the answer lies in the skies. astrophysical environments from the big bang to stars and stellar explosions are the cauldrons where all these elements are made. the papers by burbidge (rev mod phys 29:547-650, 1957) and cameron (publ astron soc pac 69:201, 1957), as well as precursors by bethe, von weizsäcker, hoyle, gamow, and suess and urey provided a very basic understanding of the nucleosynthesis processes responsible for their production, combined with nuclear physics input and required environment conditions such as temperature, density and the overall neutron/proton ratio in seed material. since then a steady stream of nuclear experiments and nuclear structure theory, astrophysical models of the early universe as well as stars and stellar explosions in single and binary stellar systems has led to a deeper understanding. this involved improvements in stellar models, the composition of stellar wind ejecta, the mechanism of core-collapse supernovae as final fate of massive stars, and the transition (as a function of initial stellar mass) from core-collapse supernovae to hypernovae and long duration gamma-ray bursts (accompanied by the formation of a black hole) in case of single star progenitors. binary stellar systems give rise to nova explosions, x-ray bursts, type ia supernovae, neutron star, and neutron star-black hole mergers. all of these events (possibly with the exception of x-ray bursts) eject material with an abundance composition unique to the specific event and lead over time to the evolution of elemental (and isotopic) abundances in the galactic gas and their imprint on the next generation of stars. in the present review, we want to give a modern overview of the nucleosynthesis processes involved, their astrophysical sites, and their impact on the evolution of galaxies. | origin of the elements |
tin sulfide (sns) is a promising absorber material for solar energy harvesting owing to the high absorption coefficient. here, a novel inverted planar heterostructure of sns based solar cell (ito/niox/sns/zno/al) has been proposed for better efficiency among the different electron transport layers (etls), pcbm, c60, ceox, and zno. the performance of the sns based solar cell was theoretically studied by the solar cell capacitance simulator (scaps) software. initially, we have been observed the device performance with different etl materials to find the better etl material. the layer parameters of the htl, absorber layer, and etls have been optimized to find out the best performance of the device. the device showed efficiencies of around 26.44%, 26.33%, and 26.38% with the etls pcbm, c60, and ceox respectively. the maximum power conversion efficiency (pce) of ~28.15% has been observed after incorporating zno etl in the designed architecture of the sns-based solar cell. then, we have been investigated the performance of the sns-based solar cell with zno etl for the various value of carrier concentration, thickness, and bulk defect of the sns absorber layer, defect of the interfaces of niox/sns and sns/zno, back metal contact's work function, and its operating temperature. the variation of the different parameters has exhibited a substantial effect on the device performance. the voc, jsc, ff, and pce of the optimized sns-based solar cell with zno etl showed 0.8954 v, 37.316452 ma cm-2, 84.24%, and 28.15%, respectively. the visualization of the results indicates that zno might be a potential etl for the highly efficient, low-cost inverted planar solar cells based on sns. | highly efficient sns-based inverted planar heterojunction solar cell with zno etl |
supernovae and their remnants are a central problem in astrophysics due to their role in the stellar evolution and nuclear synthesis. a supernova's explosion is driven by a blast wave causing the development of rayleigh-taylor and richtmyer-meshkov instabilities and leading to intensive interfacial mixing of materials of a progenitor star. rayleigh-taylor and richtmyer-meshkov mixing breaks spherical symmetry of a star and provides conditions for synthesis of heavy mass elements in addition to light mass elements synthesized in the star before its explosion. by focusing on hydrodynamic aspects of the problem, we apply group theory analysis to identify the properties of rayleigh-taylor and richtmyer-meshkov dynamics with variable acceleration, discover subdiffusive character of the blast wave-induced interfacial mixing, and reveal the mechanism of energy accumulation and transport at small scales in supernovae. | supernova, nuclear synthesis, fluid instabilities, and interfacial mixing |
heavy axion-like particles (alps), with masses ma gtrsim 100 kev, coupled with photons, would be copiously produced in a supernova (sn) core via primakoff process and photon coalescence. using a state-of-the-art sn model, we revisit the energy-loss sn 1987a bounds on axion-photon coupling. moreover, we point out that heavy alps with masses ma gtrsim 100 mev and axion-photon coupling gaγ gtrsim 4 × 10-9 gev-1 would decay into photons behind the shock-wave producing a possible enhancement in the energy deposition that would boost the sn shock revival. | heavy axion-like particles and core-collapse supernovae: constraints and impact on the explosion mechanism |
we assemble a sample of 24 hydrogen-poor superluminous supernovae (slsne). parameterizing the light-curve shape through rise and decline time-scales shows that the two are highly correlated. magnetar-powered models can reproduce the correlation, with the diversity in rise and decline rates driven by the diffusion time-scale. circumstellar interaction models can exhibit a similar rise-decline relation, but only for a narrow range of densities, which may be problematic for these models. we find that slsne are approximately 3.5 mag brighter and have light curves three times broader than sne ibc, but that the intrinsic shapes are similar. there are a number of slsne with particularly broad light curves, possibly indicating two progenitor channels, but statistical tests do not cleanly separate two populations. the general spectral evolution is also presented. velocities measured from fe ii are similar for slsne and sne ibc, suggesting that diffusion time differences are dominated by mass or opacity. flat velocity evolution in most slsne suggests a dense shell of ejecta. if opacities in slsne are similar to other sne ibc, the average ejected mass is higher by a factor 2-3. assuming κ = 0.1 cm2 g-1, we estimate a mean (median) slsn ejecta mass of 10 m⊙ (6 m⊙), with a range of 3-30 m⊙. doubling the assumed opacity brings the masses closer to normal sne ibc, but with a high-mass tail. the most probable mechanism for generating slsne seems to be the core collapse of a very massive hydrogen-poor star, forming a millisecond magnetar. | on the diversity of superluminous supernovae: ejected mass as the dominant factor |
the distance ladder using supernovae yields higher values of the hubble constant h0 than those inferred from measurements of the cosmic microwave background (cmb) and galaxy surveys, a discrepancy that has come to be known as the "hubble tension". this has motivated the exploration of extensions to the standard cosmological model in which higher values of h0 can be obtained from cmb measurements and galaxy surveys. the trouble, however, goes beyond h0; such modifications affect other quantities, too. in particular, their effects on cosmic times are usually neglected. we explore here the implications that measurements of the age tu of the universe, such as a recent inference from the age of the oldest globular clusters, can have for potential solutions to the h0 tension. the value of h0 inferred from the cmb and galaxy surveys is related to the sound horizon at cmb decoupling (or at radiation drag), but it is also related to the matter density and to tu. given this observation, we show how model-independent measurements may support or disfavor proposed new-physics solutions to the hubble tension. finally, we argue that cosmological measurements today provide constraints that, within a given cosmological model, represent an overconstrained system, offering a powerful diagnostic tool of consistency. we propose the use of ternary plots to simultaneously visualize independent constraints on key quantities related to h0 like tu, the sound horizon at radiation drag, and the matter density parameter. we envision that this representation will help find a solution to the trouble of and beyond h0. | trouble beyond h0 and the new cosmic triangles |
sno+ is a large liquid scintillator-based experiment located 2km underground at snolab, sudbury, canada. it reuses the sudbury neutrino observatory detector, consisting of a 12m diameter acrylic vessel which will be filled with about 780 tonnes of ultra-pure liquid scintillator. designed as a multipurpose neutrino experiment, the primary goal of sno+ is a search for the neutrinoless double-beta decay (0$\nu\beta\beta$) of 130te. in phase i, the detector will be loaded with 0.3% natural tellurium, corresponding to nearly 800 kg of 130te, with an expected effective majorana neutrino mass sensitivity in the region of 55-133 mev, just above the inverted mass hierarchy. recently, the possibility of deploying up to ten times more natural tellurium has been investigated, which would enable sno+ to achieve sensitivity deep into the parameter space for the inverted neutrino mass hierarchy in the future. additionally, sno+ aims to measure reactor antineutrino oscillations, low-energy solar neutrinos, and geoneutrinos, to be sensitive to supernova neutrinos, and to search for exotic physics. a first phase with the detector filled with water will begin soon, with the scintillator phase expected to start after a few months of water data taking. the 0$\nu\beta\beta$ phase i is foreseen for 2017. | current status and future prospects of the sno+ experiment |
upcoming astronomical surveys such as the large synoptic survey telescope (lsst) will rely on photometric classification to identify the majority of the transients and variables that they discover. we present a set of techniques for photometric classification that can be applied even when the training set of spectroscopically confirmed objects is heavily biased toward bright, low-redshift objects. using gaussian process regression to model arbitrary light curves in all bands simultaneously, we “augment” the training set by generating new versions of the original light curves covering a range of redshifts and observing conditions. we train a boosted decision tree classifier on features extracted from the augmented light curves, and we show how such a classifier can be designed to produce classifications that are independent of the redshift distributions of objects in the training sample. our classification algorithm was the best-performing among the 1094 models considered in the blinded phase of the photometric lsst astronomical time-series classification challenge, scoring 0.468 on the organizers’ logarithmic-loss metric with flat weights for all object classes in the training set, and achieving an auc of 0.957 for classification of sne ia. our results suggest that spectroscopic campaigns used for training photometric classifiers should focus on typing large numbers of well-observed, intermediate-redshift transients, instead of attempting to type a sample of transients that is directly representative of the full data set being classified. all of the algorithms described in this paper are implemented in the avocado software package (https://www.github.com/kboone/avocado). | avocado: photometric classification of astronomical transients with gaussian process augmentation |
using recent supernova models, i revisit the supernova 1987a constraints on scalar/pseudoscalar axion-like-particles (alps). on the basis of the neutrino detections, the luminosity of alps must be $\lesssim 5\times10^{52} \,\mathrm{erg}/s$ after the core-bounce, and this bound limits alps couplings. contrary to the qcd axion models where all couplings are $\sim 1/f_a$, it has been shown recently that a radion/dilaton could have far different coupling strength to photons and to nucleons. this fact has raised a need to establish the limits on each coupling independently. the bounds from alps emission by nucleon-nucleon bremsstrahlung through a two-nucleon coupling and by the primakoff process through a two-photon coupling are updated considering the total volume emission. i find the bounds on the two-photon coupling from the primakoff process differ from previous bounds by an order of magnitude. through the volume emission study, trapping regimes for $m_a\gtrsim10\,\mathrm{mev}$ are also alleviated, which need to be probed by future experiments. | revisiting supernova 1987a limits on axion-like-particles |
fink is a broker designed to enable science with large time-domain alert streams such as the one from the upcoming vera c. rubin observatory legacy survey of space and time (lsst). it exhibits traditional astronomy broker features such as automatized ingestion, annotation, selection, and redistribution of promising alerts for transient science. it is also designed to go beyond traditional broker features by providing real-time transient classification that is continuously improved by using state-of-the-art deep learning and adaptive learning techniques. these evolving added values will enable more accurate scientific output from lsst photometric data for diverse science cases while also leading to a higher incidence of new discoveries which shall accompany the evolution of the survey. in this paper, we introduce fink, its science motivation, architecture, and current status including first science verification cases using the zwicky transient facility alert stream. | fink, a new generation of broker for the lsst community |
monte carlo (mc) algorithms are commonly employed to explore high-dimensional parameter spaces constrained by data. all the statistical information obtained in the output of these analyses is contained in the markov chains, which one needs to process and interpret. the marginalization technique allows us to digest these chains and compute the posterior distributions for the parameter subsets of interest. in particular, it lets us draw confidence regions in two-dimensional planes, and get the constraints for the individual parameters. it is very well known, though, that the marginalized results can suffer from volume effects, which can introduce a non-negligible bias into our conclusions. the impact of these effects are barely studied in the literature. in this paper we first illustrate the problem through a very clear and simple example in two dimensions, and suggest the use of the profile distributions (pds) as a complementary tool to detect marginalization biases directly from the mc chains. we apply our method to four cosmological models: the standard λ cdm , early dark energy, coupled dark energy and the brans-dicke model with a cosmological constant. we discuss the impact of the volume effects on each model and the cosmological tensions, using the full planck 2018 likelihood, the pantheon compilation of supernovae of type ia and data on baryon acoustic oscillations. our test is very efficient and can be easily applied to any mc study. it allows us to estimate the pds at a derisory computational cost not only for the main cosmological parameters, but also for the nuisance and derived ones, and to assess the need to perform a more in-depth analysis with the exact computation of the pds. | fast test to assess the impact of marginalization in monte carlo analyses and its application to cosmology |
the tidal disruption of a star by a massive black hole is expected to yield a luminous flare of thermal emission. about two dozen of these stellar tidal disruption flares (tdfs) may have been detected in optical transient surveys. however, explaining the observed properties of these events within the tidal disruption paradigm is not yet possible. this theoretical ambiguity has led some authors to suggest that optical tdfs are due to a different process, such as a nuclear supernova or accretion disk instabilities. here we present a test of a fundamental prediction of the tidal disruption event scenario: a suppression of the flare rate due to the direct capture of stars by the black hole. using a recently compiled sample of candidate tdfs with black hole mass measurements, plus a careful treatment of selection effects in this flux-limited sample, we confirm that the dearth of observed tdfs from high-mass black holes is statistically significant. all the tdf impostor models we consider fail to explain the observed mass function; the only scenario that fits the data is a suppression of the rate due to direct captures. we find that this suppression can explain the low volumetric rate of the luminous tdf candidate asassn-15lh, thus supporting the hypothesis that this flare belongs to the tdf family. our work is the first to present the optical tdf luminosity function. a steep power law is required to explain the observed rest-frame g-band luminosity, {dn}/{{dl}}g\propto {l}g-2.5. the mean event rate of the flares in our sample is ≈ 1× {10}-4 galaxy-1 yr-1, consistent with the theoretically expected tidal disruption rate. | on the mass and luminosity functions of tidal disruption flares: rate suppression due to black hole event horizons |
in this paper, we propose a new phenomenological two parameter parameterization of q(z) to constrain barotropic dark energy models by considering a spatially flat universe, neglecting the radiation component, and reconstructing the effective equation of state (eos). this two free-parameter eos reconstruction shows a non-monotonic behavior, pointing to a more general fitting for the scalar field models, like thawing and freezing models. we constrain the q(z) free parameters using the observational data of the hubble parameter obtained from cosmic chronometers, the joint-light-analysis type ia supernovae (snia) sample, the pantheon (snia) sample, and a joint analysis from these data. we obtain, for the joint analysis with the pantheon (snia) sample a value of q(z) today, q0=-0.51 +0.09 -0.10 , and a transition redshift, zt=0.65 +0.19 -0.17 (when the universe change from an decelerated phase to an accelerated one). the effective eos reconstruction and the ω'-ω plane analysis point towards a transition over the phantom divide, i.e. ω =-1 , which is consistent with a non parametric eos reconstruction reported by other authors. | constraints on barotropic dark energy models by a new phenomenological q( z) parameterization |
asymmetric mass ejection in the early phase of supernova (sn) explosions can impart a kick velocity to the new-born neutron star (ns). for neutrino-driven explosions the ns acceleration has been shown to be mainly caused by the gravitational attraction of the anisotropically expelled inner ejecta, while hydrodynamic forces contribute on a subdominant level, and asymmetric neutrino emission plays only a secondary role. two- and three-dimensional hydrodynamic simulations have demonstrated that this gravitational tug-boat mechanism can explain the observed space velocities of young nss up to more than 1000 km s-1. here, we discuss how the ns kick depends on the energy, ejecta mass, and asymmetry of the sn explosion, and what role the compactness of the pre-collapse stellar core plays for the momentum transfer to the ns. we also provide simple analytic expressions for the ns velocity in terms of these quantities. referring to results of hydrodynamic simulations in the literature, we argue why, within the discussed scenario of ns acceleration, electron-capture sne, low-mass fe-core sne, and ultra-stripped sne can be expected to have considerably lower intrinsic ns kicks than core-collapse sne of massive stellar cores. our basic arguments also remain valid if progenitor stars possess large-scale asymmetries in their convective silicon and oxygen burning layers. possible scenarios for spin-kick alignment are sketched. much of our discussion stays on a conceptual and qualitative level, and more work is necessary on the numerical modeling side to determine the dependences of involved parameters, whose prescriptions will be needed for recipes that can be used to better describe ns kicks in binary evolution and population synthesis studies. | neutron star kicks by the gravitational tug-boat mechanism in asymmetric supernova explosions: progenitor and explosion dependence |
since core-collapse supernova simulations still struggle to produce robust neutrino-driven explosions in 3d, it has been proposed that asphericities caused by convection in the progenitor might facilitate shock revival by boosting the activity of non-radial hydrodynamic instabilities in the post-shock region. we investigate this scenario in depth using 42 relativistic 2d simulations with multigroup neutrino transport to examine the effects of velocity and density perturbations in the progenitor for different perturbation geometries that obey fundamental physical constraints (like the anelastic condition). as a framework for analysing our results, we introduce semi-empirical scaling laws relating neutrino heating, average turbulent velocities in the gain region, and the shock deformation in the saturation limit of non-radial instabilities. the squared turbulent mach number, <ma2>, reflects the violence of aspherical motions in the gain layer, and explosive runaway occurs for <ma2> ≳ 0.3, corresponding to a reduction of the critical neutrino luminosity by ∼ 25 per cent compared to 1d. in the light of this theory, progenitor asphericities aid shock revival mainly by creating anisotropic mass flux on to the shock: differential infall efficiently converts velocity perturbations in the progenitor into density perturbations δρ/ρ at the shock of the order of the initial convective mach number maprog. the anisotropic mass flux and ram pressure deform the shock and thereby amplify post-shock turbulence. large-scale (ℓ = 2, ℓ = 1) modes prove most conducive to shock revival, whereas small-scale perturbations require unrealistically high convective mach numbers. initial density perturbations in the progenitor are only of the order of ma_prog^2 and therefore play a subdominant role. | non-radial instabilities and progenitor asphericities in core-collapse supernovae |
we investigate the early impact of single and binary supernova (sn) explosions on dense gas clouds with three-dimensional, high-resolution, hydrodynamic simulations. the effect of cloud structure, radiative cooling and ionizing radiation from the progenitor stars on the net input of kinetic energy, fkin = ekin/esn, thermal energy, ftherm = etherm/esn, and gas momentum, fp = p/psn, to the interstellar medium (ism) is tested. for clouds with bar{n} = 100cm^{-3}, the momentum generating sedov and pressure-driven snowplough phases are terminated early (∝0.01 myr) and radiative cooling limits the coupling to ftherm ∼ 0.01, fkin ∼ 0.05, and fp ∼ 9, significantly lower than for the case without cooling. for pre-ionized clouds, these numbers are only increased by ∼50 per cent, independent of the cloud structure. this only suffices to accelerate ∼5 per cent of the cloud to radial velocities ≳30 km s-1. a second sn might enhance the coupling efficiencies if delayed past the sedov phase of the first explosion. such very low coupling efficiencies cast doubts on many subresolution models for sn feedback, which are, in general, validated a posteriori. ionizing radiation appears not to significantly enhance the coupling of sne to the surrounding gas as it drives the ism into inert dense shells and cold clumps, a process which is unresolved in galaxy-scale simulations. our results indicate that the momentum input of sne in ionized, structured clouds is larger (more than a factor of 10) than the corresponding momentum yield of the progenitor's stellar winds. | the energy and momentum input of supernova explosions in structured and ionized molecular clouds |
we have analysed the pantheon+ sample using a new likelihood model that replaces the single type ia supernovae (snia) absolute magnitude parameter m used in the standard likelihood model of brout et. al. with two absolute magnitude parameters (m< and m>) and a transition distance (dcrit) that determines the distance at which m changes from m< to m>. the use of this likelihood dramatically changes the quality of fit to the pantheon+ sample for a lambda cold dark matter background by δχ2 = -19.6. the tension between the m< and m> best-fitting values is at a level more than 3σ with a best-fitting dcrit very close to $20\, \mathrm{mpc}$. the origin of this improvement of fit and m<-m> tension is that the new likelihood model successfully models two signals hidden in the data: (1) the volumetric redshift scatter bias systematic and (2) a mild signal for a change of intrinsic snia luminosity at about $20\, \mathrm{mpc}$. this interpretation of the results is confirmed by truncating the z < 0.01 hubble diagram data from the pantheon+ data where the above systematic is dominant and showing that the m<-m> tension decreases from above 3σ to a little less than 2σ. it is also confirmed by performing a monte carlo simulation, which shows that the maximum significance of the snia luminosity transition ($\sigma \equiv \frac{|m_{\gt} -m_{\lt} |}{\sqrt{\sigma _{m_{\gt} }^2+\sigma _{m_{\lt} }^2}}$) as obtained from the real sh0es data is larger than the corresponding maximum significance of $94{{\ \rm per\ cent}}$ of the corresponding homogeneous simulated samples. | on the homogeneity of snia absolute magnitude in the pantheon+ sample |
it has been pointed out that there exists a tension in σ _8-ω_m measurement between cmb and lss observation. in this paper we show that σ _8-ω_m observations can be used to test the dark energy theories. we study two models, (1) hu-sawicki (hs) model of f( r) gravity and (2) chavallier-polarski-linder (cpl) parametrization of dynamical dark energy (dde), both of which satisfy the constraints from supernovae. we compute σ _8 consistent with the parameters of these models. we find that the well known tension in σ _8 between planck cmb and large scale structure (lss) observations is (1) exacerbated in the hs model and (2) somewhat alleviated in the dde model. we illustrate the importance of the σ _8 measurements for testing modified gravity models. modified gravity models change the matter power spectrum at cluster scale which also depends upon the neutrino mass. we present the bound on neutrino mass in the hs and dde model. | testing dark energy models in the light of σ _8 tension |
we present limits on the parameters of the o λ cdm , w0cdm , and w0wacdm models obtained from the joint analysis of the full-shape, baryon acoustic oscillations (bao), big bang nucleosynthesis (bbn) and supernovae data. our limits are fully independent of the data on the cosmic microwave background (cmb) anisotropies, but rival the cmb constraints in terms of parameter error bars. we find the spatial curvature consistent with a flat universe ωk=-0.043-0.036+0.036 (68% c.l.); the dark-energy equation of state parameter w0 is measured to be w0=-1.031-0.048+0.052 (68% c.l.), consistent with a cosmological constant. this conclusion also holds for the time-varying dark energy equation of state, for which we find w0=-0.98-0.11+0.099 and wa=-0.33-0.48+0.63 (both at 68% c.l.). the exclusion of the supernovae data from the analysis does not significantly weaken our bounds. this shows that using a single external bbn prior, the full-shape and bao data can provide strong cmb-independent constraints on the nonminimal cosmological models. | constraints on the curvature of the universe and dynamical dark energy from the full-shape and bao data |
we present a linear stability analysis of the fast-pairwise neutrino flavor conversion based on a result of our latest axisymmetric core-collapse supernova (ccsn) simulation with full boltzmann neutrino transport. in the ccsn simulation, coherent asymmetric neutrino emissions of electron-type neutrinos (ν e) and their antiparticles ({\bar{ν }}{{e}}), in which the asymmetries of ν e and {\bar{ν }}{{e}} are anticorrelated with each other, occur at almost the same time as the onset of aspherical shock expansion. we find that the asymmetric neutrino emissions play a crucial role on occurrences of fast flavor conversions. the linear analysis shows that unstable modes appear in both pre- and post-shock flows; for the latter, they appear only in the hemisphere of higher {\bar{ν }}{{e}} emissions (the same hemisphere with stronger shock expansion). we analyze the characteristics of electron-lepton number (eln) crossing in depth by closely inspecting the angular distributions of neutrinos in momentum space. the eln crossing happens in various ways, and the property depends on the radius: in the vicinity of neutron star, {\bar{ν }}{{e}} (ν e) dominates over ν e ({\bar{ν }}{{e}}) in the forward (backward) direction; at the larger radius, the eln crossing occurs in the opposite way. we also find that the non-radial eln crossing occurs at the boundary between no eln crossing and the radial one, which is an effect of genuine multi-dimensional transport. our findings indicate that the collective neutrino oscillation may occur more commonly in ccsne and suggest that the ccsn community needs to accommodate these oscillations self-consistently in the modeling of ccsne. | fast-pairwise collective neutrino oscillations associated with asymmetric neutrino emissions in core-collapse supernovae |
we present a suite of the first 3d grmhd collapsar simulations, which extend from the self-consistent jet launching by an accreting kerr black hole (bh) to the breakout from the star. we identify three types of outflows, depending on the angular momentum, l, of the collapsing material and the magnetic field, b, on the bh horizon: (i) subrelativistic outflow (low l and high b), (ii) stationary accretion shock instability (sasi; high l and low b), (iii) relativistic jets (high l and high b). in the absence of jets, free-fall of the stellar envelope provides a good estimate for the bh accretion rate. jets can substantially suppress the accretion rate, and their duration can be limited by the magnetization profile in the star. we find that progenitors with large (steep) inner density power-law indices (≳ 2), face extreme challenges as gamma-ray burst (grb) progenitors due to excessive luminosity, global time evolution in the light curve throughout the burst and short breakout times, inconsistent with observations. our results suggest that the wide variety of observed explosion appearances (supernova/supernova + grb/low-luminosity grbs) and the characteristics of the emitting relativistic outflows (luminosity and duration) can be naturally explained by the differences in the progenitor structure. our simulations reveal several important jet features: (i) strong magnetic dissipation inside the star, resulting in weakly magnetized jets by breakout that may have significant photospheric emission and (ii) spontaneous emergence of tilted accretion disc-jet flows, even in the absence of any tilt in the progenitor. | black hole to breakout: 3d grmhd simulations of collapsar jets reveal a wide range of transients |
in the current work, we have implemented an extension of the standard gaussian process formalism, namely the multi-task gaussian process with the ability to perform a joint learning of several cosmological data simultaneously. we have utilised the "low-redshift" expansion rate data from supernovae type-ia (sn), baryon acoustic oscillations (bao) and cosmic chronometers (cc) data in a joint analysis. we have tested several possible models of covariance functions and find very consistent estimates for cosmologically relevant parameters. in the current formalism, we also find provisions for heuristic arguments which allow us to select the best-suited kernel for the reconstruction of expansion rate data. we also utilised our method to account for systematics in cc data and find an estimate of h0 = 68.52+0.94 + 2.51 (sys)-0.94 km/s mpc-1 and a corresponding rd = 145.61+2.82 - 2.82 - 4.3 (sys) mpc as our primary result. subsequently, we find constraints on the present deceleration parameter q0 = -0.52 ± 0.06 and the transition redshift zt = 0.64+0.12-0.09. all the estimated cosmological parameters are found to be in good agreement with the standard λcdm scenario. including the local model-independent h0 estimate to the analysis we find h0 = 71.40 + 0.30 + 1.65 (sys)- 0.30km/s mpc-1 and the corresponding rd = 141.29 + 1.31 -1.31-2.63 (sys) mpc. also, the constraints on rd h0 remain consistent throughout our analysis and also with the model-dependent cmb estimate. using the script om(z) diagnostic, we find that the concordance model is very consistent within the redshift range z lesssim 2 and mildly discrepant for z gtrsim 2. | an improved model-independent assessment of the late-time cosmic expansion |
the high temperature and electron degeneracy attained during a supernova allow for the formation of a large muon abundance within the core of the resulting protoneutron star. if new pseudoscalar degrees of freedom have large couplings to the muon, they can be produced by this muon abundance and contribute to the cooling of the star. by generating the largest collection of supernova simulations with muons to date, we show that observations of the cooling rate of sn 1987a place strong constraints on the coupling of axionlike particles to muons, limiting the coupling to ga μ<10-8.1 gev-1. | muons in supernovae: implications for the axion-muon coupling |
every supernova so far observed has been considered to be the terminal explosion of a star. moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. in addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining. here we report observations of iptf14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. the light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. these characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. another possible eruption was recorded at the same position in 1954. multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability. that model, however, does not account for the continued presence of hydrogen, or the energetics observed here. another mechanism for the violent ejection of mass in massive stars may be required. | energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star |
we calculate the axion emission rate from reactions involving thermal pions in matter encountered in supernovae and neutron star mergers, identify unique spectral features, and explore their implications for astrophysics and particle physics. we find that it is about 2-5 times larger than nucleon-nucleon bremsstrahlung, which in past studies was considered to be the dominant process. the axion spectrum is also found be much harder. together, the larger rates and higher axion energies imply a stronger bound on the mass of the qcd axion and better prospects for direct detection in a large underground neutrino detector from a nearby galactic supernova. | enhanced supernova axion emission and its implications |
a crucial ingredient in population synthesis studies involving massive stars is the determination of whether they explode or implode in the end. while the final fate of a massive star is sensitive to its core structure at the onset of collapse, the existing binary population synthesis studies do not reach core collapse. instead, they employ simple prescriptions to infer their final fates without knowing the pre-supernova core structure. we explore a potential solution to this problem by treating the carbon-oxygen (co) core independently from the rest of the star. using the implicit hydrodynamics code $\mathrm{\tt {kepler}}$, we have computed an extensive grid of 3496 co-core models from a diverse range of initial conditions, each evolved from carbon ignition until core collapse. the final core structure, and thus the explodability, varies non-monotonically and depends sensitively on both the mass and initial composition of the co core. although bare co cores are not perfect substitutes for cores embedded in massive stars, our models compare well both with $\mathrm{\tt {mesa}}$ and full hydrogenic and helium star calculations. our results can be used to infer the pre-supernova core structures from population synthesis estimates of co-core properties, thus to determine the final outcomes based on the results of modern neutrino-driven explosion simulations. a sample application is presented for a population of type-iib supernova progenitors. | towards a realistic explosion landscape for binary population synthesis |
we present the early-time light curves of type ia supernovae (sne ia) observed in the first six sectors of transiting exoplanet survey satellite (tess) data. ten of these sne were discovered by asas-sn, seven by atlas, six by ztf, and one by gaia. for nine of these objects with sufficient dynamic range (>3.0 mag from detection to peak), we fit power-law models and searched for signatures of companion stars. we found a diversity of early-time light-curve shapes, although most of our sources are consistent with fireball models where the flux increases as ∝t2. three sne displayed a flatter rise with flux ∝t. we did not find any obvious evidence for additional structures, such as multiple power-law components, in the early rising light curves. for assumptions about the sn properties and the observer viewing angle (ejecta mass of 1.4 m⊙, expansion velocity of 104 km s-1, opacity of 0.2 cm2 g-1, and viewing angle of 45°) and a further assumption that any companion stars would be in roche lobe overflow, it is possible to place upper limits on the radii of any companion stars. six of the nine sne had complete coverage of the early-time light curves, and we placed upper limits on the radii of companion stars of ≲32 r⊙ for these sne, ≲20 r⊙ for five of the six, and ≲4 r⊙ for two of the six. the small sample size did not allow us to put limits on the occurrence rate of companion stars in the progenitors of sne ia. however, we expect that tess observed enough sne in its two-year primary mission (26 sectors) to either detect the signature of a large companion (r > 20 r⊙) or constrain the occurrence rate of such systems, at least for the fiducial sn properties adopted here. we also show that tess is capable of detecting emission from a 1 r⊙ companion for an sn ia within 50 mpc and has a reasonable chance of doing so after about six years. | early-time light curves of type ia supernovae observed with tess |
we present a first study of the progenitor star dependence of the three-dimensional (3d) neutrino mechanism of core-collapse supernovae. we employ full 3d general-relativistic multi-group neutrino radiation-hydrodynamics and simulate the postbounce evolutions of progenitors with zero-age main sequence masses of 12, 15, 20, 27, and 40 m ⊙. all progenitors, with the exception of the 12 m ⊙ star, experience shock runaway by the end of their simulations. in most cases, a strongly asymmetric explosion will result. we find three qualitatively distinct evolutions that suggest a complex dependence of explosion dynamics on progenitor density structure, neutrino heating, and 3d flow. (1) progenitors with massive cores, shallow density profiles, and high post-core-bounce accretion rates experience very strong neutrino heating and neutrino-driven turbulent convection, leading to early shock runaway. accretion continues at a high rate, likely leading to black hole formation. (2) intermediate progenitors experience neutrino-driven, turbulence-aided explosions triggered by the arrival of density discontinuities at the shock. these occur typically at the silicon/silicon-oxygen shell boundary. (3) progenitors with small cores and density profiles without strong discontinuities experience shock recession and develop the 3d standing-accretion shock instability (sasi). shock runaway ensues late, once declining accretion rate, sasi, and neutrino-driven convection create favorable conditions. these differences in explosion times and dynamics result in a non-monotonic relationship between progenitor and compact remnant mass. | the progenitor dependence of core-collapse supernovae from three-dimensional simulations with progenitor models of 12-40 m ⊙ |
the majority of galactic baryons resides outside of the galactic disk in the diffuse gas known as the circumgalactic medium (cgm). while state-of-the art simulations excel at reproducing galactic disk properties, many of them struggle to drive strong galactic winds or to match the observed ionization structure of the cgm using only thermal supernova feedback. to remedy this, recent studies have invoked nonthermal cosmic ray (cr) stellar feedback prescriptions. however, numerical schemes of cr transport are still poorly constrained. we explore how the choice of cr transport affects the multiphase structure of the simulated cgm. we implement anisotropic cr physics in the astrophysical simulation code enzo and simulate a suite of isolated disk galaxies with varying prescriptions for cr transport: isotropic diffusion, anisotropic diffusion, and streaming. we find that all three transport mechanisms result in strong, metal-rich outflows but differ in the temperature and ionization structure of their cgm. isotropic diffusion results in a spatially uniform, warm cgm that underpredicts the column densities of low ions. anisotropic diffusion develops a reservoir of cool gas that extends farther from the galactic center, but disperses rapidly with distance. cr streaming projects cool gas out to radii of 200 kpc, supporting a truly multiphase medium. in addition, we find that streaming is less sensitive to changes in constant parameter values like the cr injection fraction, transport velocity, and resolution than diffusion. we conclude that cr streaming is a more robust implementation of cr transport and motivates the need for detailed parameter studies of cr transport. | the role of cosmic-ray transport in shaping the simulated circumgalactic medium |
the title theory is formulated. it entails a quantum-coherent variant of the fermi-dirac distribution and casts new light on neutrino oscillations. it might enable the incorporation of neutrino mixing into the modeling of core-collapse supernovae and neutron-star mergers. | thermodynamics of oscillating neutrinos |
the spatial and velocity distributions of nuclear species synthesized in the innermost regions of core-collapse supernovae can yield important clues about explosion asymmetries and the operation of the still disputed explosion mechanism. recent observations of radioactive 44ti with high-energy satellite telescopes (nuclear spectroscopic telescope array [nustar], integral) have measured gamma-ray line details, which provide direct evidence of large-scale explosion asymmetries in sn 1987a and in cassiopeia a (cas a) even by mapping of the spatial brightness distribution (nustar). here we discuss a 3d simulation of a neutrino-driven explosion, using a parameterized neutrino engine, whose 44ti distribution is mostly concentrated in one hemisphere pointing opposite to the neutron star (ns) kick velocity. both exhibit intriguing resemblance to the observed morphology of the cas a remnant, although neither the progenitor nor the explosion was fine-tuned for a perfect match. our results demonstrate that the asymmetries observed in this remnant can, in principle, be accounted for by a neutrino-driven explosion, and that the high 44ti abundance in cas a may be explained without invoking rapid rotation or a jet-driven explosion, because neutrino-driven explosions generically eject large amounts of high-entropy matter. the recoil acceleration of the ns is connected to mass ejection asymmetries and is opposite to the direction of the stronger explosion, fully compatible with the gravitational tugboat mechanism. our results also imply that cas a and sn 1987a could possess similarly "one-sided" ti and fe asymmetries, with the difference that cas a is viewed from a direction with large inclination angle to the ns motion, whereas the ns in sn 1987a should have a dominant velocity component pointing toward us. | production and distribution of 44ti and 56ni in a three-dimensional supernova model resembling cassiopeia a |
the ‘standard’ model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present — as was inferred originally from the hubble diagram of type ia supernovae. there exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these ‘standardisable candles’ indeed indicate cosmic acceleration. taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion. | marginal evidence for cosmic acceleration from type ia supernovae |
we present the supernova explosion code (snec), an open-source lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, snec generates the bolometric light curve, as well as the light curves in different broad bands assuming blackbody emission. as a first application of snec, we consider the explosions of a grid of 15 m⊙ (at zero-age main sequence, zams) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. the resulting light curves exhibit plateaus with durations of ∼20-100 days if ≳1.5-2 m⊙ of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. if these shorter plateau lengths are not seen for sne iip in nature, it suggests that, at least for zams masses ≲20 m⊙, hydrogen mass loss occurs as an all or nothing process. this perhaps points to the important role binary interactions play in generating the observed mass-stripped supernovae (i.e., type ib/c events). these light curves are also unlike what is typically seen for sne iil, arguing that simply varying the amount of mass loss cannot explain these events. the most stripped models begin to show double-peaked light curves similar to what is often seen for sne iib, confirming previous work that these supernovae can come from progenitors that have a small amount of hydrogen and a radius of ∼500 r⊙. | light curves of core-collapse supernovae with substantial mass loss using the new open-source supernova explosion code (snec) |
galactic winds from star-forming galaxies play at key role in the evolution of galaxies and the inter-galactic medium. they transport metals out of galaxies, chemically-enriching the inter-galactic medium and modifying the chemical evolution of galaxies. they affect the surrounding inter-stellar and circum-galactic media, thereby influencing the growth of galaxies through gas accretion and star-formation. in this contribution we first summarize the physical mechanisms by which the momentum and energy output from a population of massive stars and associated supernovae can drive galactic winds. we use the proto-typical example of m82 to illustrate the multiphase nature of galactic winds. we then describe how the basic properties of galactic winds are derived from the data, and summarize how the properties of galactic winds vary systematically with the properties of the galaxies that launch them. we conclude with a brief discussion of the broad implications of galactic winds. | galactic winds and the role played by massive stars |
gravitational-wave (gw) detections are starting to reveal features in the mass distribution of double compact objects. the lower end of the black hole (bh) mass distribution is especially interesting as few formation channels contribute here and because it is more robust against variations in the cosmic star formation than the high-mass end. in this work we explore the stable mass transfer channel for the formation of gw sources with a focus on the low-mass end of the mass distribution. we conduct an extensive exploration of the uncertain physical processes that impact this channel. we note that, for fiducial assumptions, this channel reproduces the peak at ~9 m ☉ in the gw-observed binary bh mass distribution remarkably well and predicts a cutoff mass that coincides with the upper edge of the purported neutron star-black hole (ns-bh) mass gap. the peak and cutoff mass are a consequence of the unique properties of this channel; namely (1) the requirement of stability during the mass transfer phases, and (2) the complex way in which the final compact object masses scale with the initial mass. we provide an analytical expression for the cutoff in the primary component mass and show that this adequately matches our numerical results. our results imply that selection effects resulting from the formation channel alone can provide an explanation for the purported ns-bh mass gap in gw detections. this provides an alternative to the commonly adopted view that the gap emerges during bh formation. | no peaks without valleys: the stable mass transfer channel for gravitational-wave sources in light of the neutron star-black hole mass gap |
context. the majority of massive stars are part of binary systems. in about a quarter of these, the companions are so close that mass transfer occurs while they undergo core hydrogen burning, first on the thermal and then on the nuclear timescale. the nuclear timescale mass transfer leads to observational counterparts: the semi-detached so-called massive algol binaries. these systems may provide urgently needed tests of the physics of mass transfer. however, comprehensive model predictions for these systems are sparse.aims: we use a large grid of detailed evolutionary models of short-period massive binaries and follow-up population synthesis calculations to derive probability distributions of the observable properties of massive algols and their descendants.methods: our results are based on ∼10 000 binary model sequences calculated with the stellar evolution code mesa, using a metallicity suitable for the large magellanic cloud (lmc), covering initial donor masses between 10 m⊙ and 40 m⊙ and initial orbital periods above 1.4 d. these models include internal differential rotation and magnetic angular momentum transport, non-conservative mass and angular momentum transfer between the binary components, and time-dependent tidal coupling.results: our models imply ∼30, or ∼3% of the ∼1000, core hydrogen burning o-star binaries in the lmc to be currently in the semi-detached phase. our donor models are up to 25 times more luminous than single stars of an identical mass and effective temperature, which agrees with the observed algols. a comparison of our models with the observed orbital periods and mass ratios implies rather conservative mass transfer in some systems, while a very inefficient one in others. this is generally well reproduced by our spin-dependent mass transfer algorithm, except for the lowest considered masses. the observations reflect the slow increase of the surface nitrogen enrichment of the donors during the semi-detached phase all the way to cno equilibrium. we also investigate the properties of our models after core hydrogen depletion of the donor star, when these models correspond to wolf-rayet or helium+ob star binaries.conclusions: a dedicated spectroscopic survey of massive algol systems may allow to derive the dependence of the efficiency of thermal timescale mass transfer on the binary parameters, as well as the efficiency of semiconvective mixing in the stellar interior. this would be a crucial step towards reliable binary models up to the formation of supernovae and compact objects. | detailed models of interacting short-period massive binary stars |
recent studies have shown that the observed colour distributions of type ia sne (snia) are well-described by a combination of distributions from dust and intrinsic colour. here we present a new forward-modeling fitting method (dust2dust) to measure the parent dust and colour distributions, including their dependence on host-galaxy mass. at each fit step, the snia selection efficiency is determined from a large simulated sample that is re-weighted to reflect the proposed distributions. we use five separate metrics to constrain the dust2dust parameters: distribution of fitted light-curve colour $c$, cosmological residual trends with $c$, cosmological residual scatter with $c$, fitted colour-luminosity relationship $\beta_{\rm salt2}$, and intrinsic scatter $\sigma_{\rm int}$. using the pantheon+ data sample, we present results for a dust2dust fit that includes 4 parameters describing intrinsic colour variations and 8 parameters describing dust. furthermore, we propagate the dust2dust parameter uncertainties and covariance to the dark energy equation-of-state $w$ and hubble constant h$_0$: we find $\sigma_w = 0.005$ and $\sigma_{\textrm{h}_0} = 0.145~$km/s/mpc. the dust2dust code is publically available. | the pantheon+ analysis: forward-modeling the dust and intrinsic colour distributions of type ia supernovae, and quantifying their impact on cosmological inferences |
dark matter could be a thermal relic comprised of strongly interacting massive particles (simps), where 3 →2 interactions set the relic abundance. such interactions generically arise in theories of chiral symmetry breaking via the wess-zumino-witten term. in this work, we show that an axionlike particle can successfully maintain kinetic equilibrium between the dark matter and the visible sector, allowing the requisite entropy transfer that is crucial for simps to be a cold dark matter candidate. constraints on this scenario arise from beam dump and collider experiments, from the cosmic microwave background, and from supernovae. we find a viable parameter space when the axionlike particle is close in mass to the simp dark matter, with strong-scale masses of order a few hundred mev. many planned experiments are set to probe the parameter space in the near future. | strongly interacting massive particles through the axion portal |
we propose a new simple formalism to predict the orbital separations after common-envelope phases with massive-star donors. we focus on the fact that massive red supergiants tend to have a sizable radiative layer between the dense helium core and the convective envelope. our formalism treats the common-envelope phase in two stages: dynamical inspiral through the outer convective envelope and thermal timescale mass transfer from the radiative intershell. with fiducial choices of parameters, the new formalism typically predicts much wider separations compared to the classical energy formalism. moreover, our formalism predicts that final separations strongly depend on the donor evolutionary stage and companion mass. our formalism provides a physically motivated alternative option for population synthesis studies to treat common-envelope evolution. this treatment will impact predictions for massive-star binaries, including gravitational-wave sources, x-ray binaries, and stripped-envelope supernovae. | a two-stage formalism for common-envelope phases of massive stars |
we map the trends of elemental abundance ratios across the galactic disk, spanning r=3{--}15 {kpc} and midplane distance | z| =0{--}2 {kpc}, for 15 elements in a sample of 20,485 stars measured by the sdss/apogee survey (o, na, mg, al, si, p, s, k, ca, v, cr, mn, fe, co, ni). adopting mg rather than fe as our reference element, and separating stars into two populations based on [fe/mg], we find that the median trends of [x/mg] versus [mg/h] in each population are nearly independent of location in the galaxy. the full multi-element cartography can be summarized by combining these nearly universal median sequences with our measured metallicity distribution functions and the relative proportions of the low-[fe/mg] (high-α) and high-[fe/mg] (low-α) populations, which depend strongly on r and | z| . we interpret the median sequences with a semi-empirical “two-process” model that describes both the ratio of core collapse and type ia supernova (sn ia) contributions to each element and the metallicity dependence of the supernova yields. these observationally inferred trends can provide strong tests of supernova nucleosynthesis calculations. our results lead to a relatively simple picture of abundance ratio variations in the milky way, in which the trends at any location can be described as the sum of two components with relative contributions that change systematically and smoothly across the galaxy. deviations from this picture and future extensions to other elements can provide further insights into the physics of stellar nucleosynthesis and unusual events in the galaxy’s history. | chemical cartography with apogee: multi-element abundance ratios |
massive stars, supernovae, and kilonovae are among the most luminous radiation sources in the universe. observations usually show near- to mid-infrared (nir-mir, λ ≈ 1-5 μm) emission excess from h ii regions around young massive star clusters. early-phase observations in optical-to-nir wavelengths of type ia supernovae also reveal unusual properties of dust extinction and dust polarization. the most common explanation for such nir-mir excess and unusual dust properties is the predominance of small grains (size a ≲ 0.05 μm) relative to large grains (a ≳ 0.1 μm) in the local environment of these strong radiation sources. however, why small grains might be predominant in these environments is unclear. here we report a mechanism of dust destruction based on centrifugal stress within extremely fast-rotating grains spun-up by radiative torques, which we term radiative torque disruption (ratd). we find that ratd can disrupt large grains located within a distance of about a parsec from a massive star of luminosity l ≈ 104l⊙, where l⊙ is the solar luminosity, or from a supernova. this disruption effect increases the abundance of small grains relative to large grains and successfully reproduces the observed nir-mir excess and anomalous dust extinction/polarization. we apply the ratd mechanism for kilonovae and find that dust within about 0.1 parsec would be dominated by small grains. small grains produced by ratd can also explain the steep far-ultraviolet rise in extinction curves towards starburst and high-redshift galaxies, and the decrease of the escape fraction of lyman α photons from h ii regions surrounding young massive star clusters. | rotational disruption of dust grains by radiative torques in strong radiation fields |
we report evidence for excess blue light from the type ia supernova (sn ia) sn 2012cg at 15 and 16 days before maximum b-band brightness. the emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. this is the first evidence for emission from a companion to a normal sn ia. sixteen days before maximum light, the b-v color of sn 2012cg is 0.2 mag bluer than for other normal sn ia. at later times, this supernova has a typical sn ia light curve, with extinction-corrected {m}b=-19.62+/- 0.02 mag and {{δ }}{m}15(b)=0.86+/- 0.02. our data set is extensive, with photometry in seven filters from five independent sources. early spectra also show the effects of blue light, and high-velocity features are observed at early times. near maximum, the spectra are normal with a silicon velocity vsi = -10,500 km s-1. comparing the early data with models by kasen favors a main-sequence companion of about six solar masses. it is possible that many other sn ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint. | sn 2012cg: evidence for interaction between a normal type ia supernova and a non-degenerate binary companion |
we calculate the evolution of massive stars, which undergo pulsational pair-instability (ppi) when the o-rich core is formed. the evolution from the main sequence through the onset of ppi is calculated for stars with initial masses of 80-140 m ⊙ and metallicities of z = 10-3-1.0 z ⊙. because of mass loss, z ≤ 0.5 z ⊙ is necessary for stars to form he cores massive enough (i.e., mass >40 m ⊙) to undergo ppi. the hydrodynamical phase of evolution from ppi through the beginning of fe-core collapse is calculated for he cores with masses of 40-62 m ⊙ and z = 0. during ppi, electron-positron pair production causes a rapid contraction of the o-rich core, which triggers explosive o-burning and a pulsation of the core. we study the mass dependence of the pulsation dynamics, thermodynamics, and nucleosynthesis. the pulsations are stronger for more massive he cores and result in a large amount of mass ejection such as 3-13 m ⊙ for 40-62 m ⊙ he cores. these he cores eventually undergo fe-core collapse. the 64 m ⊙ he core undergoes complete disruption and becomes a pair-instability supernova. the h-free circumstellar matter ejected around these he cores is massive enough to explain the observed light curve of type i (h-free) superluminous supernovae with circumstellar interaction. we also note that the mass ejection sets the maximum mass of black holes (bhs) to be ∼50 m ⊙, which is consistent with the masses of bhs recently detected by virgo and aligo. | pulsational pair-instability supernovae. i. pre-collapse evolution and pulsational mass ejection |
two sources of geometric information are encoded in the galaxy power spectrum: the sound horizon at recombination and the horizon at matter-radiation equality. analyzing the boss 12th data release galaxy power spectra using perturbation theory with ωm priors from pantheon supernovae but no priors on ωb, we obtain constraints on h0 from the second scale, finding h0=65.1-5.4+3.0 km s-1 mpc-1 ; this differs from the best fit of sh0es at 95% confidence. similar results are obtained if ωm is constrained from uncalibrated baryon acoustic oscillations: h0=65.6-5.5+3.4 km s-1 mpc-1 . adding the analogous lensing results from baxter and sherwin from 2020, the posterior shifts to 70.6-5.0+3.7 km s-1 mpc-1 . using mock data, fisher analyses, and scale cuts, we demonstrate that our constraints do not receive significant information from the sound horizon scale. since many models resolve the h0 controversy by adding new physics to alter the sound horizon, our measurements are a consistency test for standard cosmology before recombination. a simple forecast indicates that such constraints could reach σh0≃1.6 km s-1 mpc-1 in the era of euclid. | determining the hubble constant without the sound horizon: measurements from galaxy surveys |
in this manuscript we reassess the potential of interacting dark matter-dark energy models in solving the hubble constant tension. these models have been proposed but also questioned as possible solutions to the h0 problem. here we examine several interacting scenarios against cosmological observations, focusing on the important role played by the calibration of supernovae data. in order to reassess the ability of interacting dark matter-dark energy scenarios in easing the hubble constant tension, we systematically confront their theoretical predictions using a prior on the supernovae ia absolute magnitude mb, which has been argued to be more robust and certainly less controversial than using a prior on the hubble constant h0. while some data combinations do not show any preference for interacting dark sectors and in some of these scenarios the clustering σ8 tension worsens, interacting cosmologies with a dark energy equation of state w <-1 are preferred over the canonical λ cdm picture even with cosmic microwave background data alone and also provide values of σ8 in perfect agreement with those from weak lensing surveys. future cosmological surveys will test these exotic dark energy cosmologies by accurately measuring the dark energy equation of state and its putative redshift evolution. | late-time interacting cosmologies and the hubble constant tension |
exascale computing could soon enable a predictive theory of nuclear structure and reactions rooted in the standard model, with quantifiable and systematically improvable uncertainties. such a predictive theory will help exploit experiments that use nucleons and nuclei as laboratories for testing the standard model and its limitations. examples include direct dark matter detection, neutrinoless double beta decay, and searches for permanent electric dipole moments of the neutron and atoms. it will also help connect qcd to the properties of cold neutron stars and hot supernova cores. we discuss how a quantitative bridge between qcd and the properties of nuclei and nuclear matter will require a synthesis of lattice qcd (especially as applied to two- and three-nucleon interactions), effective field theory, and ab initio methods for solving the nuclear many-body problem. while there are significant challenges that must be addressed in developing this triad of theoretical tools, the rapid advance of computing is accelerating progress. in particular, we focus this review on the anticipated advances from lattice qcd and how these advances will impact few-body effective theories of nuclear physics by providing critical input, such as constraints on unknown low-energy constants of the effective (field) theories. we also review particular challenges that must be overcome for the successful application of lattice qcd for low-energy nuclear physics. we describe progress in developing few-body effective (field) theories of nuclear physics, with an emphasis on hobet, a non-relativistic effective theory of nuclear physics, which is less common in the literature. we use the examples of neutrinoless double beta decay and the nuclear-matter equation of state to illustrate how the coupling of lattice qcd to effective theory might impact our understanding of symmetries and exotic astrophysical environments. | towards grounding nuclear physics in qcd |
in this article we compare a variety of well-known dynamical dark energy models using the cosmic microwave background measurements from the 2018 planck legacy and 2015 planck data releases, the baryon acoustic oscillations measurements and the local measurements of h0 obtained by the sh0es (supernovae, h0, for the equation of state of dark energy) collaboration analysing the hubble space telescope data. we discuss the alleviation of h0 tension, that is obtained at the price of a phantom-like dark energy equation of state. we perform a bayesian evidence analysis to quantify the improvement of the fit, finding that all the dark energy models considered in this work are preferred against the λcdm scenario. finally, among all the possibilities analysed, the cpl model is the best one in fitting the data and solving the h0 tension at the same time. however, unfortunately, this dynamical dark energy solution is not supported by the baryon acoustic oscillations (bao) data, and the tension is restored when bao data are included for all the models. | dynamical dark energy after planck cmb final release and h0 tension |
motivated by the exciting features and a recent proposed general form of the function of non-metricity scalar q, we investigate the cosmological implications in f(q) gravity, through the resulting effective dark energy sector, extracting analytical expressions for the dark energy density, equation-of-state and the deceleration parameters. we show that even in the absence of a cosmological constant, the universe exhibits the usual thermal history, with the sequence of matter and dark energy eras, and the dark-energy equation-of-state parameter always lie in the phantom regime. additionally, calculating the age of the universe, through the extracted analytical equations of the scenario at hand, we show that the result coincide with the value corresponding to λcdm scenario within 1σ. moreover, we show the excellent agreement of the scenario at hand with supernovae type ia observational data. lastly, comparing the cosmological behavior in the case of the absence of an explicit cosmological constant, with the one of the presence of a cosmological constant we show that f(q) gravity can mimic the cosmological constant in a very efficient way, providing very similar behavior, revealing the advantages and capabilitites of the scenario at hand. | late-time cosmology with phantom dark-energy in f(q) gravity |
tin (ii) sulfide (sns) is a layered mineral found in nature. in this paper, we study the two-dimensional (2d) form of this material using a combination of ab initio calculation and k .p theory. in particular, we address the valley properties and the optical selection rules of 2d sns. our study reveals sns as an extraordinary material, where there are two pairs of valleys, each placed along the two perpendicular axes, which can be selected exclusively with linearly polarized light, and can be separated using nonlocal electrical measurements. | valley physics in tin (ii) sulfide |
superluminous supernovae are a new class of supernovae that were recognized about a decade ago. both observational and theoretical progress has been significant in the last decade. in this review, we first briefly summarize the observational properties of superluminous supernovae. we then introduce the three major suggested luminosity sources to explain the huge luminosities of superluminous supernovae, i.e., the nuclear decay of 56ni, the interaction between supernova ejecta and dense circumstellar media, and the spin down of magnetars. we compare these models and discuss their strengths and weaknesses. | superluminous supernovae |
we determine limits from sn 1987a on massive axionlike particles with masses in the 10 kev-100 mev range and purely coupled to two photons. axionlike particles produced in the core collapse escape from the star and decay into photons that can be observed as a delayed and diffuse burst. we discuss the time and angular distribution of such a signal. looking into the future, we also estimate the possible improvements caused by better gamma-ray detectors or the explosion of the red supergiant betelgeuse in a supernova event. | decay photons from the axionlike particles burst of type ii supernovae |
the proposal that core collapse supernovae are neutrino driven is still the subject of active investigation more than 50 years after the seminal paper by colgate and white. the modern version of this paradigm, which we owe to wilson, proposes that the supernova shock wave is powered by neutrino heating, mediated by the absorption of electron-flavor neutrinos and antineutrinos emanating from the proto-neutron star surface, or neutrinosphere. neutrino weak interactions with the stellar core fluid, the theory of which is still evolving, are flavor and energy dependent. the associated neutrino mean free paths extend over many orders of magnitude and are never always small relative to the stellar core radius. thus, neutrinos are never always fluid like. instead, a kinetic description of them in terms of distribution functions that determine the number density of neutrinos in the six-dimensional phase space of position, direction, and energy, for both neutrinos and antineutrinos of each flavor, or in terms of angular moments of these neutrino distributions that instead provide neutrino number densities in the four-dimensional phase-space subspace of position and energy, is needed. in turn, the computational challenge is twofold: (i) to map the kinetic equations governing the evolution of these distributions or moments onto discrete representations that are stable, accurate, and, perhaps most important, respect physical laws such as conservation of lepton number and energy and the fermi-dirac nature of neutrinos and (ii) to develop efficient, supercomputer-architecture-aware solution methods for the resultant nonlinear algebraic equations. in this review, we present the current state of the art in attempts to meet this challenge. | physical, numerical, and computational challenges of modeling neutrino transport in core-collapse supernovae |
understanding the escape of lyman continuum (lyc) and lyman alpha (lyα) photons from molecular clouds is one of the keys to constraining the reionization history of the universe. using a set of radiation-hydrodynamic simulations, we investigate how photons propagate and escape from turbulent clouds with different masses, star formation efficiencies (sfes), and metallicities, as well as with different models of stellar spectra and supernova feedback. we find that the escape fractions in both lyc and lyα are generally increasing with time if the cloud is efficiently dispersed by radiation and supernova feedback. when the total sfe is low (1 per cent of the cloud mass), 0.1-5{{ per cent}} of lyc photons leave the metal-poor cloud, whereas the fractions increase to 20-70{{ per cent}} in clouds with a 10 per cent sfe. lyc photons escape more efficiently if gas metallicity is lower, if the upper mass limit in the stellar initial mass function is higher, if binary interactions are allowed in the evolution of stars, or if additional strong radiation pressure, such as lyα pressure, is present. the escape fractions of lyα photons are systemically higher (60-80{{ per cent}}) than those of lyc photons, despite large optical depths at line centre (τ0 ∼ 106-109). scattering of lyα photons is already significant on cloud scales, leading to double-peaked profiles with peak separations of v_sep∼ 400 {{km s^{-1}}} during the initial stage of the cloud evolution, while it becomes narrower than v_sep ≲ 150 {{km s^{-1}}} in the lyc bright phase. comparisons with observations of low-redshift galaxies suggest that lyα photons require further interactions with neutral hydrogen to reproduce their velocity offset for a given lyc escape fraction. | understanding the escape of lyc and lyα photons from turbulent clouds |
dense clouds of neutrinos and antineutrinos can exhibit fast collective flavor oscillations. previously, in [s. bhattacharyya and b. dasgupta, phys. rev. lett. 126, 061302 (2021)., 10.1103/physrevlett.126.061302], we proposed that such flavor oscillations lead to depolarization—i.e., an irreversible mixing of the flavors—whose extent depends on the initial momentum distributions of the different flavors. in this paper, we elaborate and extend this proposal, and compare it with related results in the literature. we present an accurate analytical estimate for the lower resting point of the fast flavor pendulum and underline the relaxation mechanisms—i.e., transverse relaxation, multipole cascade, and mixing of flavor waves—that cause it to settle down. we estimate the extent of depolarization, its dependence on momentum and net lepton asymmetry, and its generalization to three flavors. finally, we prescribe approximate analytical recipes for the depolarized distributions and fluxes that can be used in supernova/nucleosynthesis simulations and supernova neutrino phenomenology. | elaborating the ultimate fate of fast collective neutrino flavor oscillations |
the universe may feature large-scale inhomogeneities beyond the standard paradigm, implying that statistical homogeneity and isotropy may be reached only on much larger scales than the usually assumed ~100 mpc. this means that we are not necessarily typical observers and that the copernican principle could be recovered only on super-hubble scales. here, we do not assume the validity of the copernican principle and let cosmic microwave background, baryon acoustic oscillations, type ia supernovae, local h 0, cosmic chronometers, compton y-distortion and kinetic sunyaev-zeldovich observations constrain the geometrical degrees of freedom of the local structure, which we parametrize via the λltb model-basically a non-linear radial perturbation of a flrw metric. in order to quantify if a non-copernican structure could explain away the hubble tension, we pay careful attention to computing the hubble constant in an inhomogeneous universe, and we adopt model selection via both the bayes factor and the akaike information criterion. our results show that, while the λltb model can successfully explain away the h 0 tension, it is favored with respect to the λcdm model only if one solely considers supernovae in the redshift range that is used to fit the hubble constant, that is, 0.023 < z < 0.15. if one considers all the supernova sample, then the h 0 tension is not solved and the support for the λltb model vanishes. combined with other data sets, this solution to the hubble tension barely helps. finally, we have reconstructed our local spacetime. we have found that data are best fit by a shallow void with δ l ≈ -0.04 and ${r}_{\mathrm{l}}^{\text{out}}\approx 300$ mpc, which, interestingly, lies on the border of the 95% credible region relative to the standard model expectation. | a void in the hubble tension? the end of the line for the hubble bubble |
most treatments of neutrino flavor evolution, above a surface of the last scattering, take identical angular distributions on this surface for the different initial (unmixed) flavors, and for particles and antiparticles. differences in these distributions must be present, as a result of the species-dependent scattering cross sections lower in the star. these lead to a new set of nonlinear equations, unstable even at the initial surface with respect to perturbations that break all-over spherical symmetry. there could be important consequences for explosion dynamics as well as for the neutrino pulse in the outer regions. | neutrino cloud instabilities just above the neutrino sphere of a supernova |
the current discrepancy between the hubble constant, h0, derived from the local distance ladder and from the cosmic microwave background is one of the most crucial issues in cosmology, as it may possibly indicate unknown systematics or new physics. here, we present a novel non-parametric method to estimate the hubble constant as a function of redshift. we establish independent estimates of the evolution of hubble constant by diagonalizing the covariance matrix. from type ia supernovae, baryon acoustic oscillation data and the observed hubble parameter data, a decreasing trend in the hubble constant with a significance of a 5.6σ confidence level is found. at low redshift, its value is dramatically consistent with that measured from the local distance ladder and it drops to the value measured from the cosmic microwave background at high redshift. our results may relieve the hubble tension, with a preference for recent solutions, especially with respect to novel physics. | evidence of a decreasing trend for the hubble constant |
in this document, the technical details of the jsns$^2$ (j-parc sterile neutrino search at j-parc spallation neutron source) experiment are described. the search for sterile neutrinos is currently one of the hottest topics in neutrino physics. the jsns$^2$ experiment aims to search for the existence of neutrino oscillations with $\delta m^2$ near 1 ev$^2$ at the j-parc materials and life science experimental facility (mlf). a 1 mw beam of 3 gev protons incident on a spallation neutron target produces an intense neutrino beam from muon decay at rest. neutrinos come predominantly from $\mu^+$ decay: $\mu^{+} \to e^{+} + \bar{\nu}_{\mu} + \nu_{e}$. the experiment will search for $\bar{\nu}_{\mu}$ to $\bar{\nu}_{e}$ oscillations which are detected by the inverse beta decay interaction $\bar{\nu}_{e} + p \to e^{+} + n$, followed by gammas from neutron capture on gd. the detector has a fiducial volume of 17 tons and is located 24 meters away from the mercury target. jsns$^2$ offers the ultimate direct test of the lsnd anomaly. in addition to the sterile neutrino search, the physics program includes cross section measurements with neutrinos with a few 10's of mev from muon decay at rest and with monochromatic 236 mev neutrinos from kaon decay at rest. these cross sections are relevant for our understanding of supernova explosions and nuclear physics. | technical design report (tdr): searching for a sterile neutrino at j-parc mlf (e56, jsns2) |
recent weak lensing surveys have revealed that the direct measurement of the parameter combination $s_8\equiv\sigma_8(\omega_m/0.3)^{0.5}$ -- where $\sigma_8$ is a measure of the amplitude of matter fluctuations on 8 $h^{-1}$mpc scales -- is $\sim3\sigma$ discrepant with the value reconstructed from cosmic microwave background (cmb) data assuming the $\lambda$cdm model. in this article, we show that it is possible to resolve the tension if dark matter (dm) decays with a lifetime of $\gamma^{-1} \simeq 55 \ \text{gyrs}$ into one massless and one massive product, and transfers a fraction $\varepsilon\simeq 0.7 \ \%$ of its rest mass energy to the massless component. the velocity-kick received by the massive daughter leads to a suppression of gravitational clustering below its free-streaming length, thereby reducing the $\sigma_8$ value as compared to that inferred from the standard $\lambda$cdm model, in a similar fashion to massive neutrino and standard warm dm. contrarily to the latter scenarios, the time-dependence of the power suppression and the free-streaming scale allows the 2-body decaying dm scenario to accommodate cmb, baryon acoustic oscillation, growth factor and un-calibrated supernova ia data. we briefly discuss implications for dm model building, galactic small-scale structure problems and the recent xenon-1t excess. future experiments measuring the growth factor to high accuracy at $0\lesssim z\lesssim1$ can further test this scenario. | implications of the $s_8$ tension for decaying dark matter with warm decay products |
models of pair-instability supernovae (pisne) predict a gap in black hole (bh) masses between ∼45 m⊙ and 120 m⊙, which is referred to as the upper bh mass-gap. with the advent of gravitational-wave astrophysics, it has become possible to test this prediction, and there is an important associated effort to understand which theoretical uncertainties modify the boundaries of this gap. in this work we study the impact of rotation on the hydrodynamics of pisne, which leave no compact remnant, as well as the evolution of pulsational-pisne (ppisne), which undergo thermonuclear eruptions before forming a compact object. we perform simulations of nonrotating and rapidly rotating stripped helium stars in a metal-poor environment (z⊙/50) in order to resolve the lower edge of the upper mass-gap. we find that the outcome of our simulations is dependent on the efficiency of angular momentum transport: models that include efficient coupling through the spruit-tayler dynamo shift the lower edge of the mass-gap upward by ∼4%, while simulations that do not include this effect shift it upward by ∼15%. from this, we expect that the lower edge of the upper mass-gap is dependent on bh spin, which can be tested as the number of observed bh mergers increases. moreover, we show that stars undergoing ppisne have extended envelopes (r ∼ 10 - 1000 r⊙) at iron-core collapse, making them promising progenitors for ultra-long gamma-ray bursts. | the impact of stellar rotation on the black hole mass-gap from pair-instability supernovae |
we investigate the thermal emission and extinction from dust associated with the nearby superluminous supernova (slsn) 2018bsz. our dataset has daily cadence and simultaneous optical and near-infrared coverage up to ~ 100 days, together with late time (+ 1.7 yr) mir observations. at 230 days after light curve peak the sn is not detected in the optical, but shows a surprisingly strong near-infrared excess, with r - j > 3 mag and r - ks > 5 mag. the time evolution of the infrared light curve enables us to investigate if the mid-infrared emission is from newly formed dust inside the sn ejecta, from a pre-existing circumstellar envelope, or interstellar material heated by the radiation from the sn. we find the latter two scenarios can be ruled out, and a scenario where new dust is forming in the sn ejecta at epochs > 200 days can self-consistently reproduce the evolution of the sn flux. we can fit the spectral energy distribution well at +230 d with 5 x 10^-4 solar mass of carbon dust, increasing over the following several hundred days to 10^-2 solar mass by +535 d. sn 2018bsz is the first slsn showing evidence for dust formation within the sn ejecta, and appears to form ten times more dust than normal core-collapse sne at similar epochs. together with their preference for low mass, low metallicity host galaxies, we suggest that slsne may be a significant contributor to dust formation in the early universe. | sn 2018bsz: significant dust formation in a nearby superluminous supernova |
we consider gamma-ray burst (grb) jets that are choked by extended material as sources of high-energy cosmic neutrinos. we take into account the jet propagation physics both inside the progenitor star and the surrounding dense medium. radiation constraints, which are relevant for high-energy neutrino production, are considered as well. efficient shock acceleration of cosmic rays is possible for sufficiently low-power jets and/or jets buried in a dense, extended wind or outer envelope. such conditions also favor grb jets to become stalled, and the necessary conditions for stalling are explicitly derived. such choked jets may explain transrelativistic supernovae (sne) and low-luminosity (ll) grbs, giving a unified picture of grbs and grb-sne. focusing on this unified scenario for grbs, we calculate the resulting neutrino spectra from choked jets, including the relevant microphysical processes such as multipion production in p p and p γ interactions, as well as the energy losses of mesons and muons. we obtain diffuse neutrino spectra using the latest results for the luminosity function of ll grbs. although uncertainties are large, we confirm that ll grbs can potentially give a significant contribution to the diffuse neutrino flux. our results are consistent with the present icecube data and do not violate the stacking limits on classical high-luminosity grbs. we find that high-energy neutrino production in choked jets is dominated by p γ interactions. these sources are dark in gev-tev gamma rays and do not contribute significantly to the fermi diffuse gamma-ray background. assuming stalled jets can launch a quasispherical shock in the dense medium, "precursor" tev neutrinos emerging prior to the shock breakout gamma-ray emission can be used as smoking-gun evidence for a choked jet model for ll grbs. our results strengthen the relevance of wide field-of-view sky monitors with better sensitivities in the 1-100 kev range. | choked jets and low-luminosity gamma-ray bursts as hidden neutrino sources |
we investigate the impact of cosmic rays (crs) on galactic outflows from a multiphase interstellar medium with solar neighbourhood conditions. the three-dimensional magnetohydrodynamical simulations include crs as a relativistic fluid in the advection-diffusion approximation. the thermal and chemical state of the interstellar medium is computed with a non-equilibrium chemical network. we find that crs [injected with 10 per cent of the supernova (sn) energy] efficiently support the launching of outflows and strongly affect their phase structure. outflows leaving the midplane are denser (ρ ∼ 10^{-26} g cm^{-3}), colder ({∼ } 10^4 k) and slower ({∼ } 30 km s^{-1}) if crs are considered in addition to thermal sne. the cr-supported outflows are also smoother, in particular at larger heights (>1 kpc above the midplane) without the direct impact of sn explosions. approximately, 5 per cent - 25 per cent of the injected cr energy is lost via hadronic cooling. smaller diffusion coefficients lead to slightly larger hadronic losses but allow for steeper cr pressure gradients, stronger outflows and larger accelerations. up to a height of z ∼ 1 kpc, there are large volumes in approximate pressure equilibrium between the thermal and the cr component. at larger altitudes, the cr pressure is 10-100 times as large as the thermal counterpart. more than {∼ } 1 kpc away from the midplane, crs provide the dominant gas acceleration mechanism. | cooler and smoother - the impact of cosmic rays on the phase structure of galactic outflows |
the prolonged near infrared (nir) emission observed following the long duration grb 211211a is inconsistent with afterglow emission from the shock driven into the circum-stellar medium (csm), and with emission from a possible underlying supernova. it has therefore been suggested that the observed nir flux is the signature of a kilonova -- a radioactive ejecta that is similar to the outcome of the binary neutron star merger gw170817. we propose here an alternative plausible explanation. we show that the nir flux is consistent with thermal emission from dust, heated by uv and soft x-ray radiation produced by the interaction of the grb jet plasma with the csm. this nir emission was predicted by waxman & draine for grbs residing near or withing massive molecular clouds. the dust nir emission scenario is consistent with a grb at $z\lesssim1$. inspection of the environment of grb 211211a suggests that there are at least two host-galaxy candidates, one at $z=0.076$ and the other at $z=0.459$. the $z=0.459$ possibility is also consistent with the non-detection of a supernova signature in the light curve of the grb afterglow, and with a typical grb $\gamma$-ray energy for the fluence of grb 211211a. | strong nir emission following the long duration grb 211211a: dust heating as an alternative to a kilonova |
we present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type ia supernovae discovered by the dark energy survey supernova program (des-sn) and used in the first des-sn cosmological analysis. for the des-sn sample, when considering a 5d (z, x1, c, α, β) bias correction, we find evidence of a hubble residual 'mass step', where sne ia in high-mass galaxies (>1010m⊙) are intrinsically more luminous (after correction) than their low-mass counterparts by $\gamma =0.040\pm 0.019$ mag. this value is larger by 0.031 mag than the value found in the first des-sn cosmological analysis. this difference is due to a combination of updated photometric measurements and improved star formation histories and is not from host-galaxy misidentification. when using a 1d (redshift-only) bias correction the inferred mass step is larger, with $\gamma =0.066\pm 0.020$ mag. the 1d-5d γ difference for des-sn is $0.026\pm 0.009$ mag. we show that this difference is due to a strong correlation between host galaxy stellar mass and the x1 component of the 5d distance-bias correction. including an intrinsic correlation between the observed properties of sne ia, stretch and colour, and stellar mass in simulated sn ia samples, we show that a 5d fit recovers γ with -9 mmag bias compared to a +2 mmag bias for a 1d fit. this difference can explain part of the discrepancy seen in the data. improvements in modelling correlations between galaxy properties and sn is necessary to ensure unbiased precision estimates of the dark energy equation of state as we enter the era of lsst. | first cosmology results using type ia supernovae from the dark energy survey: the effect of host galaxy properties on supernova luminosity |
we present observations of sn 2015bn (=ps15ae = css141223-113342+004332 = mls150211-113342+004333), a type i superluminous supernova (slsn) at redshift z = 0.1136. as well as being one of the closest slsne i yet discovered, it is intrinsically brighter ({m}u≈ -23.1) and in a fainter galaxy ({m}b≈ -16.0) than other slsne at z∼ 0.1. we used this opportunity to collect the most extensive data set for any slsn i to date, including densely sampled spectroscopy and photometry, from the uv to the nir, spanning -50 to +250 days from optical maximum. sn 2015bn fades slowly, but exhibits surprising undulations in the light curve on a timescale of 30-50 days, especially in the uv. the spectrum shows extraordinarily slow evolution except for a rapid transformation between +7 and +20-30 days. no narrow emission lines from slow-moving material are observed at any phase. we derive physical properties including the bolometric luminosity, and find slow velocity evolution and non-monotonic temperature and radial evolution. a deep radio limit rules out a healthy off-axis gamma-ray burst, and places constraints on the pre-explosion mass loss. the data can be consistently explained by a ≳ 10 m {}⊙stripped progenitor exploding with ∼ {10}51 erg kinetic energy, forming a magnetar with a spin-down timescale of ∼20 days (thus avoiding a gamma-ray burst) that reheats the ejecta and drives ionization fronts. the most likely alternative scenario—interaction with ∼20 m {}⊙of dense, inhomogeneous circumstellar material—can be tested with continuing radio follow-up. | sn 2015bn: a detailed multi-wavelength view of a nearby superluminous supernova |
ridged, orthorhombic two-dimensional atomic crystals with a bulk {\em pnma} structure such as black phosphorus and monochalcogenide monolayers are an exciting and novel material platform for a host of applications. key to their crystallinity, monolayers of these materials have a four-fold degenerate structural ground state, and a single energy scale $e_c$ (representing the elastic energy required to switch the longer lattice vector along the $x-$ or $y-$direction) determines how disordered these monolayers are at finite temperature. disorder arises when nearest neighboring atoms become gently reassigned as the system is thermally excited beyond a critical temperature $t_c$ that is proportional to $e_c/k_b$. $e_c$ is tunable by chemical composition and it leads to a classification of these materials into two categories: (i) those for which $e_c\ge k_bt_m$, and (ii) those having $k_bt_m>e_c\ge 0$, where $t_m$ is a given material's melting temperature. black phosphorus and sis monolayers belong to category (i): these materials do not display an intermediate order-disorder transition and melt directly. all other monochalcogenide monolayers with $e_c>0$ belonging to class (ii) will undergo a two-dimensional transition prior to melting. $e_c/k_b$ is slightly larger than room temperature for ges and gese, and smaller than 300 k for sns and snse monolayers, so that these materials transition near room temperature. the onset of this generic atomistic phenomena is captured by a planar potts model up to the order-disorder transition. the order-disorder phase transition in two dimensions described here is at the origin of the {\em cmcm} phase being discussed within the context of bulk layered snse. | two-dimensional disorder in black phosphorus and monochalcogenide monolayers |
there is growing observational evidence for dwarf galaxies hosting active galactic nuclei (agn), including hints of agn-driven outflows in dwarfs. however, in the common theoretical model of galaxy formation, efficient supernova (sn) feedback is the tool of choice for regulating star formation in the low-mass regime. in this paper, we present a suite of high-resolution cosmological dwarf zoom-in simulations relaxing the assumption of strong sn feedback, with the goal to determine whether more moderate sn feedback in combination with an efficient agn could be a suitable alternative. importantly, we find that there are sufficient amounts of gas to power brief eddington-limited accretion episodes in dwarfs. this leads to a variety of outcomes depending on the agn accretion model: from no additional suppression to moderate regulation of star formation to catastrophic quenching. efficient agn can drive powerful outflows, depleting the gas reservoir of their hosts via ejective feedback and then maintaining a quiescent state through heating the circumgalactic medium. moderate agn outflows can be as efficient as the strong sn feedback commonly employed, leading to star formation regulation and h i gas masses in agreement with observations of field dwarfs. all efficient agn set-ups are associated with overmassive black holes (bhs) compared to the (heavily extrapolated) observed bh mass-stellar mass scaling relations, with future direct observational constraints in this mass regime being crucially needed. efficient agn activity is mostly restricted to high redshifts, with hot, accelerated outflows and high x-ray luminosities being the clearest tell-tale signs for future observational campaigns. | two can play at that game: constraining the role of supernova and agn feedback in dwarf galaxies with cosmological zoom-in simulations |
we present details on the observing strategy, data-processing techniques, and spectroscopic targeting algorithms for the first three years of operation for the dark energy survey supernova program (des-sn). this five-year program using the dark energy camera mounted on the 4 m blanco telescope in chile was designed to discover and follow supernovae (sne) ia over a wide redshift range (0.05 < z < 1.2) to measure the equation-of-state parameter of dark energy. we describe the sn program in full: strategy, observations, data reduction, spectroscopic follow-up observations, and classification. from three seasons of data, we have discovered 12,015 likely sne, 308 of which have been spectroscopically confirmed, including 251 sne ia over a redshift range of 0.017 < z < 0.85. we determine the effective spectroscopic selection function for our sample and use it to investigate the redshift-dependent bias on the distance moduli of sne ia we have classified. the data presented here are used for the first cosmology analysis by des-sn ("des-sn3yr"), the results of which are given in dark energy survey collaboration et al. the 489 spectra that are used to define the des-sn3yr sample are publicly available at https://des.ncsa.illinois.edu/releases/sn. | first cosmology results using supernovae ia from the dark energy survey: survey overview, performance, and supernova spectroscopy |
the role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate galactic winds. microscopic cosmic-ray transport processes are fundamental for determining the efficiency of cosmic-ray wind driving. previous studies modeled cosmic-ray transport either via a constant diffusion coefficient or via streaming proportional to the alfvén speed. however, in predominantly cold, neutral gas, cosmic rays can propagate faster than in the ionized medium, and the effective transport can be substantially larger; i.e., cosmic rays can decouple from the gas. we perform three-dimensional magnetohydrodynamical simulations of patches of galactic disks including the effects of cosmic rays. our simulations include the decoupling of cosmic rays in the cold, neutral interstellar medium. we find that, compared to the ordinary diffusive cosmic-ray transport case, accounting for the decoupling leads to significantly different wind properties, such as the gas density and temperature, significantly broader spatial distribution of cosmic rays, and higher wind speed. these results have implications for x-ray, γ-ray, and radio emission, and for the magnetization and pollution of the circumgalactic medium by cosmic rays. | impact of cosmic-ray transport on galactic winds |
fast flavor conversions of supernova neutrinos, possible near the neutrinosphere, depends on an interesting interplay of collisions and neutrino oscillations. contrary to naïve expectations, the rate of self-induced neutrino oscillations, due to neutrino-neutrino forward scattering, comfortably exceeds the rate of collisions even deep inside the supernova core. consistently accounting for collisions and oscillations, we present the first calculations to show that collisions can create the conditions for fast flavor conversions of neutrinos, but oscillations can continue without significant damping thereafter. this may have interesting consequences for supernova explosions and the nature of its associated neutrino emission. | collisional triggering of fast flavor conversions of supernova neutrinos |
we present an exquisite 30 minute cadence kepler (k2) light curve of the type ia supernova (sn ia) 2018oh (asassn-18bt), starting weeks before explosion, covering the moment of explosion and the subsequent rise, and continuing past peak brightness. these data are supplemented by multi-color panoramic survey telescope (pan-starrs1) and rapid response system 1 and cerro tololo inter-american observatory 4 m dark energy camera (ctio 4-m decam) observations obtained within hours of explosion. the k2 light curve has an unusual two-component shape, where the flux rises with a steep linear gradient for the first few days, followed by a quadratic rise as seen for typical supernovae (sne) ia. this “flux excess” relative to canonical sn ia behavior is confirmed in our i-band light curve, and furthermore, sn 2018oh is especially blue during the early epochs. the flux excess peaks 2.14 ± 0.04 days after explosion, has a fwhm of 3.12 ± 0.04 days, a blackbody temperature of t=17,{500}-9,000+11,500 k, a peak luminosity of 4.3+/- 0.2× {10}37 {erg} {{{s}}}-1, and a total integrated energy of 1.27+/- 0.01× {10}43 {erg}. we compare sn 2018oh to several models that may provide additional heating at early times, including collision with a companion and a shallow concentration of radioactive nickel. while all of these models generally reproduce the early k2 light curve shape, we slightly favor a companion interaction, at a distance of ∼2× {10}12 {cm} based on our early color measurements, although the exact distance depends on the uncertain viewing angle. additional confirmation of a companion interaction in future modeling and observations of sn 2018oh would provide strong support for a single-degenerate progenitor system. | k2 observations of sn 2018oh reveal a two-component rising light curve for a type ia supernova |
we present the results of a multiwavelength campaign targeting frb 20201124a, the third closest repeating fast radio burst (frb), which was recently localized in a nearby (z = 0.0978) galaxy. deep vla observations led to the detection of quiescent radio emission, which was also marginally visible in x-rays with chandra. imaging at 22 ghz allowed us to resolve the source on a scale of ≳1″ and locate it at the position of the frb, within an error of 0.2″. the evn and e-merlin observations sampled small angular scales, from 2 to 100 mas, providing tight upper limits on the presence of a compact source and evidence for diffuse radio emission. we argue that this emission is associated with enhanced star formation activity in the proximity of the frb, corresponding to a star formation rate (sfr) of ≈10 m⊙ yr−1. the surface sfr at the location of frb 20201124a is two orders of magnitude larger than what is typically observed in other precisely localized frbs. such a high sfr is indicative of this frb source being a newborn magnetar produced from a supernova explosion of a massive star progenitor. upper limits to the x-ray counterparts of 49 radio bursts observed in our simultaneous fast, srt, and chandra campaign are consistent with a magnetar scenario. | the fast radio burst frb 20201124a in a star-forming region: constraints to the progenitor and multiwavelength counterparts |
automated classification of supernovae (sne) based on optical photometric light-curve information is essential in the upcoming era of wide-field time domain surveys, such as the legacy survey of space and time (lsst) conducted by the rubin observatory. photometric classification can enable real-time identification of interesting events for extended multiwavelength follow-up, as well as archival population studies. here we present the complete sample of 5243 "sn-like" light curves (in gp1rp1ip1zp1) from the pan-starrs1 medium-deep survey (ps1-mds). the ps1-mds is similar to the planned lsst wide-fast-deep survey in terms of cadence, filters, and depth, making this a useful training set for the community. using this data set, we train a novel semisupervised machine learning algorithm to photometrically classify 2315 new sn-like light curves with host galaxy spectroscopic redshifts. our algorithm consists of an rf supervised classification step and a novel unsupervised step in which we introduce a recurrent autoencoder neural network (raenn). our final pipeline, dubbed superraenn, has an accuracy of 87% across five sn classes (type ia, ibc, ii, iin, slsn-i) and macro-averaged purity and completeness of 66% and 69%, respectively. we find the highest accuracy rates for sne ia and slsne and the lowest for sne ibc. our complete spectroscopically and photometrically classified samples break down into 62.0% type ia (1839 objects), 19.8% type ii (553 objects), 4.8% type iin (136 objects), 11.7% type ibc (291 objects), and 1.6% type i slsne (54 objects). | superraenn: a semisupervised supernova photometric classification pipeline trained on pan-starrs1 medium-deep survey supernovae |
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