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we report a spectroscopic search for hypervelocity white dwarfs (wds) that are runaways from type ia supernovae (sne ia) and related thermonuclear explosions. candidates are selected from gaia data with high tangential velocities and blue colors. we find six new runaways, including four stars with radial velocities (rvs) $>1000\,\rm km\,s^{-1}$ and total space velocities $\gtrsim 1300\,\rm km\,s^{-1}$. these are most likely the surviving donors from double-degenerate binaries in which the other wd exploded. the other two objects have lower minimum velocities, $\gtrsim 600\,\rm km\,s^{-1}$, and may have formed through a different mechanism, such as pure deflagration of a wd in a type iax supernova. the four fastest stars are hotter and smaller than the previously known "d$^6$ stars," with effective temperatures ranging from $\sim$20,000 to $\sim$130,000 k and radii of $\sim 0.02-0.10\,r_{\odot}$. three of these have carbon-dominated atmospheres, and one has a helium-dominated atmosphere. two stars have rvs of $-1694$ and $-2285\rm \,km\,s^{-1}$ -- the fastest systemic stellar rvs ever measured. their inferred birth velocities, $\sim 2200-2500\,\rm km\,s^{-1}$, imply that both wds in the progenitor binary had masses $>1.0\,m_{\odot}$. the high observed velocities suggest that a dominant fraction of the observed hypervelocity wd population comes from double-degenerate binaries whose total mass significantly exceeds the chandrasekhar limit. however, the two nearest and faintest d$^6$ stars have the lowest velocities and masses, suggesting that observational selection effects favor rarer, higher-mass stars. a significant population of fainter low-mass runaways may still await discovery. we infer a birth rate of d$^6$ stars that is consistent with the sn ia rate. the birth rate is poorly constrained, however, because the luminosities and lifetimes of $\rm d^6$ stars are uncertain. | the fastest stars in the galaxy |
the vera c. rubin legacy survey of space and time (lsst) holds the potential to revolutionize time domain astrophysics, reaching completely unexplored areas of the universe and mapping variability time scales from minutes to a decade. to prepare to maximize the potential of the rubin lsst data for the exploration of the transient and variable universe, one of the four pillars of rubin lsst science, the transient and variable stars science collaboration, one of the eight rubin lsst science collaborations, has identified research areas of interest and requirements, and paths to enable them. while our roadmap is ever-evolving, this document represents a snapshot of our plans and preparatory work in the final years and months leading up to the survey's first light. | rubin observatory lsst transients and variable stars roadmap |
in the next decades, the gravitational-wave (gw) standard siren observations and the neutral hydrogen 21-cm intensity mapping (im) surveys, as two promising cosmological probes, will play an important role in precisely measuring cosmological parameters. in this work, we make a forecast for cosmological parameter estimation with the synergy between the gw standard siren observations and the 21-cm im surveys. we choose the einstein telescope (et) and the taiji observatory as the representatives of the gw detection projects and choose the square kilometre array (ska) phase i mid-frequency array as the representative of the 21-cm im experiments. in the simulation of the 21-cm im data, we assume perfect foreground removal and calibration. we find that the synergy of the gw standard siren observations and the 21-cm im survey could break the cosmological parameter degeneracies. the joint et +taiji +ska data give σ (h0)=0.28 km s-1 mpc-1 in the λ cdm model, σ (w )=0.028 in the w cdm model, which are better than the results of p l a n c k +bao +sne , and σ (w0)=0.077 and σ (wa)=0.295 in the cpl model, which are comparable with the results of p l a n c k +bao +sne . in the λ cdm model, the constraint precision of h0 and ωm is less than or rather close to 1%, indicating that the magnificent prospects for precision cosmology with these two promising cosmological probes are worth expecting. | how can gravitational-wave standard sirens and 21-cm intensity mapping jointly provide a precise late-universe cosmological probe? |
we construct a sample of 644 carbon-enhanced metal-poor (cemp) stars with abundance analyses based on moderate- to high-resolution spectroscopic studies. dynamical parameters for these stars are estimated based on radial velocities, bayesian parallax-based distance estimates, and proper motions from gaia edr3 and dr3, supplemented by additional available information where needed. after separating our sample into the different cemp morphological groups in the yoon-beers diagram of absolute carbon abundance versus metallicity, we used the derived specific energies and actions (e, jr , jϕ , jz ) to cluster them into chemodynamically tagged groups (cdtgs). we then analyzed the elemental-abundance dispersions within these clusters by comparing them to the dispersion of clusters that were generated at random. we find that, for the group i (primarily cemp-s and cemp-r/s) clustered stars, there exist statistically insignificant intracluster dispersions in [fe/h], [c/fe] c(evolution corrected carbon), and [mg/fe] when compared to the intracluster dispersions of randomly clustered group i cemp stars. in contrast, the group ii (primarily cemp-no) stars exhibit clear similarities in their intracluster abundances, with very low, statistically significant, dispersions in [c/fe] cand marginally significant results in [mg/fe]. these results strongly indicate that group i cemp stars received their carbon enhancements from local phenomena, such as mass transfer from an evolved binary companion in regions with extended star formation histories, while the cdtgs of group ii cemp stars formed in low-metallicity environments that had already been enriched in carbon, likely from massive rapidly rotating ultra- and hyper-metal-poor stars and/or supernovae associated with high-mass early-generation stars. | chemodynamically tagged groups of cemp stars in the halo of the milky way. i. untangling the origins of cemp-s and cemp-no stars |
stellar models predict that lithium (li) inside a star is destroyed during the first dredge-up phase, yet 1.2% of red giant stars are li-rich. we aim to uncover possible origins of this population, by analysing 1155 li-rich giants (a(li) $\geq$ 1.5) in galah dr3. to expose peculiar traits of li-rich stars, we construct a reference sample of li-normal (doppelgänger) stars with matched evolutionary state and fiducial supernova abundances. comparing li-rich and doppelgänger spectra reveals systematic differences in the h-$\alpha$ and ca-triplet line profiles associated with the velocity broadening measurement. we also find twice as many li-rich stars appear to be fast rotators (2% with $v_\textrm{broad} \gtrsim 20$ km s$^{-1}$) compared to doppelgängers. on average, li-rich stars have higher abundances than their doppelgängers, for a subset of elements, and li-rich stars at the base of rgb have higher mean $s-$process abundances ($\geq 0.05$ dex for ba, y, zr), relative to their doppelgängers. external mass-transfer from intermediate-mass agb companions could explain this signature. additional companion analysis excludes binaries with mass ratios $\gtrsim$ 0.5 at $\gtrsim$ 7 au. we also discover that highly ba-enriched stars are missing from the li-rich population, possibly due to low-mass agb companions which preclude li-enrichment. finally, we confirm a prevalence of li-rich stars on the red clump that increases with lithium, which supports an evolutionary state mechanism for li-enhancement. multiple culprits, including binary spin-up and mass-transfer, are therefore likely mechanisms of li-enrichment. | many roads lead to lithium: formation pathways for lithium-rich red giants |
supernova (sn) 2023ixf was discovered by k. itagaki in the very nearby galaxy (d=6.4 mpc; shappee & stanek 2011, apj, 733, 124) messier 101 (m101; ngc 5457) on 05/19/2023 and has been classified as a type ii sn by perley et al. (astronote 2023-119). | spitzer constraints on pre-explosion variability of the sn 2023ixf progenitor |
in this study, the cztsse (cu2znsn(s,se)4) solar cells, with al/zno:al/zno (i)/cds/cztsse/mo structure, have been simulated. the simulation results have been compared and validated with real experimental results. next, suggestions for improving the performance of cztsse solar cell have been provided. a sns layer has been used as back surface field (bsf) layer. different physical parameters of sns layer are investigated, and the optimum values are selected. it has been found that by inserting a bsf layer with optimum parameters, the efficiency of cztsse solar cell increases from 12.3% to 17.25% due to enhancement of both short-circuit current density (jsc) and open circuit voltage (voc). for this optimized cell structure, the maximum jsc = 37.37 ma/cm2, voc = 0.605 v, and fill factor = 76.28% are obtained under 1.5 am illumination. | improve the performance of cztsse solar cells by applying a sns bsf layer |
we present the holismokes programme on strong gravitational lensing of supernovae (sne) as a probe of sn physics and cosmology. we investigate the effects of microlensing on early-phase sn ia spectra using four different sn explosion models. we find that distortions of sn ia spectra due to microlensing are typically negligible within ten rest-frame days after a sn explosion (< 1% distortion within the 1σ spread and ≲10% distortion within the 2σ spread). this shows the great prospects of using lensed sne ia to obtain intrinsic early-phase sn spectra for deciphering sn ia progenitors. as a demonstration of the usefulness of lensed sne ia for cosmology, we simulate a sample of mock lensed sn ia systems that are expected to have accurate and precise time-delay measurements in the era of the rubin observatory legacy survey of space and time (lsst). adopting realistic yet conservative uncertainties on their time-delay distances and lens angular diameter distances, of 6.6% and 5%, respectively, we find that a sample of 20 lensed sne ia would allow us to constrain the hubble constant (h0) with 1.3% uncertainty in the flat λcdm cosmology. we find a similar constraint on h0 in an open λcdm cosmology, while the constraint degrades to 3% in a flat wcdm cosmology. we anticipate lensed sne to be an independent and powerful probe of sn physics and cosmology in the upcoming lsst era. | holismokes. i. highly optimised lensing investigations of supernovae, microlensing objects, and kinematics of ellipticals and spirals |
while the evolution of superbubbles driven by clustered supernovae has been studied by numerous authors, the resulting radial momentum yield is uncertain by as much as an order of magnitude depending on the computational methods and assumed properties of the surrounding interstellar medium (ism). in this work, we study the origin of these discrepancies, and seek to determine the correct momentum budget for a homogeneous ism. we carry out 3d hydrodynamic and magnetohydrodynamic (mhd) simulations of clustered supernova explosions, using a lagrangian method and checking for convergence with respect to resolution. we find that the terminal momentum of a shell driven by clustered supernovae is dictated primarily by the mixing rate across the contact discontinuity between the hot and cold phases, and that this energy mixing rate is dominated by numerical diffusion even at the highest resolution we can complete, 0.03 m⊙. magnetic fields also reduce the mixing rate, so that mhd simulations produce higher momentum yields than hd ones at equal resolution. as a result, we obtain only a lower limit on the momentum yield from clustered supernovae. combining this with our previous 1d results, which provide an upper limit because they allow almost no mixing across the contact discontinuity, we conclude that the momentum yield per supernova from clustered supernovae in a homogeneous ism is bounded between 2 × 105 and 3 × 106 m⊙ km s-1. a converged value for the simple homogeneous ism remains elusive. | the momentum budget of clustered supernova feedback in a 3d, magnetized medium |
extended material at large radii surrounding a supernova (sn) can result in a double-peaked light curve. this occurs when the material is sufficiently massive that the sn shock continues to propagate into it and sufficiently extended that it produces a bright first peak. such material can be the leftover, low-mass envelope of a star that has been highly stripped, the mass associated with a wind, or perhaps mass surrounding the progenitor due to some type of pre-explosion activity. i summarize the conditions necessary for such a light curve to occur, describe what can be learned about the extended material from the light curve shape, and provide an analytic model for fitting the first peak in these double-peaked sne. this is applied to the specific case of a type ic super-luminous sn, lsq14bdq. the mass in the extended material around this explosion’s progenitor is measured to be small, ∼ 0.3-0.5 {m}⊙ . the radius of this material can be ∼ 500-5000 {r}⊙ , but it is difficult to constrain due to a degeneracy between radius and the sn’s energy. in the future, spectra taken during the first peak will be important for measuring the velocity and composition of the extended material so that this degeneracy can be overcome. | using double-peaked supernova light curves to study extended material |
context. elements heavier than li are produced in the interiors of stars. however, for many elements the exact production sites and the timescales on which they are dispersed into the interstellar medium are unknown. having a clear picture on the origins of the elements is important for our ability to trace and understand the formation and chemical evolution of the milky way and its stellar populations.aims: the aim of this study is to investigate the origin and evolution of sc, v, mn, and co for a homogeneous and statistically significant sample of stars probing the different populations of the milky way, in particular the thin and thick disks.methods: using high-resolution spectra obtained with the mike, feros, sofin, fies, uves, and harps spectrographs, we determine sc, v, mn, and co abundances for a large sample of f and g dwarfs in the solar neighborhood. the method is based on spectral synthesis and using one-dimensional, plane-parallel, local thermodynamic equilibrium (lte) model stellar atmospheres calculated with the marcs 2012 code. the non-lte (nlte) corrections from the literature were applied to mn and co.results: we find that the abundance trends derived for sc (594 stars), v (466 stars), and co (567 stars) are very similar to what has been observed for the α-elements in the thin and thick disks. on the contrary, mn (569 stars) is generally underabundant relative to the sun (i.e., [ mn/fe ] < 0) for [ fe/h ] < 0. in addition, for mn, when nlte corrections are applied, the trend changes and is almost flat over the entire metallicity range of the stars in our sample (-2 ≲ [ fe/h ] ≲ + 0.4). the [sc/fe]-[fe/h] abundance trends show a small separation between the thin and thick disks, while for v and co they completely overlap. for mn there is a small difference in [mn/fe], but only when nlte corrections are used. comparisons with ti as a reference element show flat trends for all the elements except for mn that show well separated [mn/ti]-[ti/h] trends for the thin and thick disks.conclusions: the elements sc and v present trends compatible with production from type ii supernovae (snii) events. in addition, sc clearly shows a metallicity dependence for [ fe/h ] < -1. instead, mn is produced in snii events for [ fe/h ] ≲ -0.4 and then type ia supernovae start to produce mn. finally, co appears to be produced mainly in snii with suggestion of enrichment from hypernovae at low metallicities. this paper includes data gathered with the 6.5 m magellan telescopes located at the las campanas observatory, chile; the nordic optical telescope (not) on la palma, spain; the very large telescope (vlt) at the european southern observatory (eso) on paranal, chile (eso proposal id 69.b-0277 and 72.b-0179); the eso 1.5-m, 2.2-m. and 3.6-m telescopes on la silla, chile (eso proposal id 65.l-0019, 67.b-0108, 76.b-0416, 82.b-0610); and data from uves paranal observatory project (eso ddt program id 266.d-5655).full versions of tables 2 and 5 are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/577/a9appendices are available in electronic form at http://www.aanda.org | the origin and evolution of the odd-z iron-peak elements sc, v, mn, and co in the milky way stellar disk |
in binary black hole mergers from isolated binary-star evolution, both black holes are from progenitor stars that have lost their hydrogen-rich envelopes by binary mass transfer. envelope stripping is known to affect the pre-supernova core structures of such binary-stripped stars and thereby their final fates and compact remnant masses. in this paper, we show that binary-stripped stars give rise to a bimodal black hole mass spectrum with characteristic black hole masses of about 9 m ⊙ and 16 m ⊙ across a large range of metallicities. the bimodality is linked to carbon and neon burning becoming neutrino dominated, which results in interior structures that are difficult to explode and likely lead to black hole formation. the characteristic black hole masses from binary-stripped stars have corresponding features in the chirp-mass distribution of binary black hole mergers: peaks at about 8 and 14 m ⊙ and a dearth in between these masses. current gravitational-wave observations of binary black hole mergers show evidence for a gap at 10-12 m ⊙ and peaks at 8 and 14 m ⊙ in the chirp-mass distribution. these features are in agreement with our models of binary-stripped stars. in the future, they may be used to constrain the physics of late stellar evolution and supernova explosions and may even help measure the cosmological expansion of the universe. | bimodal black hole mass distribution and chirp masses of binary black hole mergers |
mev-scale energy depositions by low-energy photons produced in neutrino-argon interactions have been identified and reconstructed in argoneut liquid argon time projection chamber (lartpc) data. argoneut data collected on the numi beam at fermilab were analyzed to select isolated low-energy depositions in the tpc volume. the total number, reconstructed energies, and positions of these depositions have been compared to those from simulations of neutrino-argon interactions using the fluka monte carlo generator. measured features are consistent with energy depositions from photons produced by deexcitation of the neutrino's target nucleus and by inelastic scattering of primary neutrons produced by neutrino-argon interactions. this study represents a successful reconstruction of physics at the mev scale in a lartpc, a capability of crucial importance for detection and reconstruction of supernova and solar neutrino interactions in future large lartpcs. | demonstration of mev-scale physics in liquid argon time projection chambers using argoneut |
the universe is awash with tens-of-mev neutrinos of all species coming from all past core-collapse supernovae. these have never been observed, but this state of affairs will change in the near future. in less than ten years, the super-kamiokande experiment, loaded with gadolinium, is expected to collect dozens of events induced by the scattering of neutrinos from the diffuse supernova neutrino background (dsnb). next-generation projects, including hyper-kamiokande and theia, are expected to collect data samples with hundreds of dsnb events after a decade of running. here, we study quantitatively how well the dsnb, including its energy spectrum, will be measured by different current or upcoming large neutrino detectors. we analyze the simulated data in order to estimate how well measurements of the dsnb can be used to inform research topics in cosmology—including measurements of the hubble parameter—astrophysics—including the star-formation rate—and particle physics—including the neutrino lifetime and the possibility that neutrinos are pseudo-dirac fermions. | fundamental physics with the diffuse supernova background neutrinos |
we study theoretical neutrino signals from core-collapse supernova (ccsn) computed using axisymmetric ccsn simulations that cover the post-bounce phase up to ~4 s. we provide basic quantities of the neutrino signals such as event rates, energy spectra, and cumulative number of events at some terrestrial neutrino detectors, and then discuss some new features in the late phase that emerge in our models. contrary to popular belief, neutrino emissions in the late phase are not always steady, but rather have temporal fluctuations, the vigour of which hinges on the ccsn model and neutrino flavour. we find that such temporal variations are not primarily driven by proto-neutron star convection, but by fallback accretion in exploding models. we assess the detectability of these temporal variations, and find that icecube is the most promising detector with which to resolve them. we also update fitting formulae first proposed in our previous paper for which the total neutrino energy emitted at the ccsn source is estimated from the cumulative number of events in each detector. this will be a powerful technique with which to analyse real observations, particularly for low-statistics data. | supernova neutrino signals based on long-term axisymmetric simulations |
in late 2014, four images of supernova (sn) "refsdal," the first known example of a strongly lensed sn with multiple resolved images, were detected in the macs j1149 galaxy-cluster field. following the images' discovery, the sn was predicted to reappear within hundreds of days at a new position ~8″ away in the field. the observed reappearance in late 2015 makes it possible to carry out refsdal's original proposal to use a multiply imaged sn to measure the hubble constant h 0, since the time delay between appearances should vary inversely with h 0. moreover, the position, brightness, and timing of the reappearance enable a novel test of the blind predictions of galaxy-cluster models, which are typically constrained only by the positions of multiply imaged galaxies. we have developed a new photometry pipeline that uses dolphot to measure the fluxes of the five images of sn refsdal from difference images. we apply four separate techniques to perform a blind measurement of the relative time delays and magnification ratios between the last image sx and the earlier images s1-s4. we measure the relative time delay of sx-s1 to be $\displaystyle {376.0}_{-5.5}^{+5.6}$ days and the relative magnification to be $\displaystyle {0.30}_{-0.3}^{+0.5}$ . this corresponds to a 1.5% precision on the time delay and 17% precision for the magnification ratios and includes uncertainties due to millilensing and microlensing. in an accompanying paper, we place initial and blind constraints on the value of the hubble constant. | the magnificent five images of supernova refsdal: time delay and magnification measurements |
low-redshift measurements of baryon acoustic oscillations (bao) measure the late-time evolution of the universe and are a vital probe of dark energy. over the past decade both the 6-degree field galaxy survey (6dfgs) and sloan digital sky survey main galaxy sample (sdss mgs) have provided important distance constraints at z < 0.3. in this paper we re-evaluate the cosmological information from the bao detection in 6dfgs making use of halo occupation distribution (hod)-populated comoving lagrangian acceleration (cola) mocks for an accurate covariance matrix and take advantage of the now commonly implemented technique of density field reconstruction. for the 6dfgs data, we find consistency with the previous analysis, and obtain an isotropic volume-averaged distance measurement of dv(z_{eff}=0.097) = [372± 17(± ^{98}_{33})](rs/rs^{fid}) mpc but with a highly non-gaussian likelihood. we combine our measurement from both the post-reconstruction clustering of 6dfgs and sdss mgs offering an updated constraint in this redshift regime, dv(z_{eff}=0.122)=[539± 17(± ^{35}_{39})](rs/r^{fid}s) mpc. this measurement tightens the constraint in comparison to the result from sdss mgs alone, especially at the 2σ and higher significance levels. these measurements are consistent with standard λcold dark matter (λcdm) and after fixing the standard ruler using a planck prior on ωmh2, the joint analysis gives h0=64.0± 3.5 km s^{-1} mpc^{-1}. this result is consistent with other bao and cosmic microwave background (cmb) studies but is in >2σ tension with supernova distance ladder measurements. in the near future both the taipan galaxy survey and the dark energy spectroscopic instrument (desi) will improve this measurement to 1% at low redshift. | low redshift baryon acoustic oscillation measurement from the reconstructed 6-degree field galaxy survey |
fallback in core-collapse supernovae plays a crucial role in determining the properties of the compact remnants and of the ejecta composition. we perform three-dimensional simulations of mixing and fallback for selected non-rotating supernova models to study how explosion energy and asymmetries correlate with the remnant mass, remnant kick, and remnant spin. we find that the strongest kick and spin are imparted by partial fallback in an asymmetric explosion. black hole (bh) kicks of several hundred $\mathrm{km}\, \mathrm{s}^{-1}$ and spin parameters of $\mathord {\sim }0.25$ can be obtained in this scenario. if the initial explosion energy barely exceeds the envelope binding energy, stronger fallback results, and the remnant kick and spin remain small. if the explosion energy is high with respect to the envelope binding energy, there is little fallback with a small effect on the remnant kick, but the spin-up by fallback can be substantial. for a non-rotating $12\, \mathrm{m}_\odot$ progenitor, we find that the neutron star is spun up to millisecond periods. the high specific angular momentum of the fallback material can also lead to disc formation around bhs. fallback may thus be a pathway towards millisecond-magnetar or collapsar-type engines for hypernovae and gamma-ray bursts that does not require rapid progenitor rotation. within our small set of simulations, none reproduced the peculiar layered fallback necessary to explain the metal-rich iron-poor composition of many carbon-enhanced metal-poor (cemp) stars. models with different explosion energy and different realizations of asymmetries may, however, be compatible with cemp abundance patterns. | the impact of fallback on the compact remnants and chemical yields of core-collapse supernovae |
recent arcsecond localizations of fast radio bursts and identifications of their host galaxies confirmed their extragalactic origin. while frb 121102 resides in the bright region of a dwarf star-forming galaxy, other frbs reside in more massive galaxies and are related to older stellar populations. we compare the host galaxy properties of nine frbs with those of several types of stellar transients: from young to old populations, long-duration gamma-ray bursts (lgrbs), superluminous supernovae (slsne), sne ibc, sne ii, sne ia, and short-duration gamma-ray bursts (sgrbs). we find that the stellar mass and star formation rate of the frb host galaxies, taken as a whole sample, prefer a medium to old population, and are against a young population, similar to lgrbs and slsne by a null probability of 0.02. individually, the host of frb 121102 is consistent with that of young population objects; the environment of frb 180924 is similar to that of sgrbs; and the environment of frb 190523 is similar to those of sne ia. these results are consistent with the magnetar engine model for frbs, if magnetars produced from extreme explosions (grbs/slsne) and those from regular channels (e.g., those producing galactic magnetars) can both produce frbs. | a comparative study of host galaxy properties between fast radio bursts and stellar transients |
we explore the variation in single-star 15-30 {m}⊙ , nonrotating, solar metallicity, pre-supernova mesa models that is due to changes in the number of isotopes in a fully coupled nuclear reaction network and adjustments in the mass resolution. within this two-dimensional plane, we quantitatively detail the range of core masses at various stages of evolution, mass locations of the main nuclear burning shells, electron fraction profiles, mass fraction profiles, burning lifetimes, stellar lifetimes, and compactness parameter at core collapse for models with and without mass-loss. up to carbon burning, we generally find that mass resolution has a larger impact on the variations than the number of isotopes, while the number of isotopes plays a more significant role in determining the span of the variations for neon, oxygen, and silicon burning. choice of mass resolution dominates the variations in the structure of the intermediate convection zone and secondary convection zone during core and shell hydrogen burning, respectively, where we find that a minimum mass resolution of ≈0.01 {m}⊙is necessary to achieve convergence in the helium core mass at the ≈5% level. on the other hand, at the onset of core collapse, we find ≈30% variations in the central electron fraction and mass locations of the main nuclear burning shells, a minimum of ≈127 isotopes is needed to attain convergence of these values at the ≈10% level. | on variations of pre-supernova model properties |
the empirical upper luminosity boundary lmax of cool supergiants (sgs), often referred to as the humphreys-davidson limit, is thought to encode information on the general mass-loss behaviour of massive stars. further, it delineates the boundary at which single stars will end their lives stripped of their hydrogen-rich envelope, which in turn is a key factor in the relative rates of type-ii to type-ibc supernovae from single star channels. in this paper we have revisited the issue of lmax by studying the luminosity distributions of cool sgs in the large and small magellanic clouds (lmc/smc). we assemble samples of cool sgs in each galaxy which are highly complete above logl/l⊙= 5.0, and determine their spectral energy distributions from the optical to the mid-infrared using modern multiwavelength survey data. we show that in both cases lmax appears to be lower than previously quoted, and is in the region of log l/l⊙ = 5.5. there is no evidence for lmax being higher in the smc than in the lmc, as would be expected if metallicity-dependent winds were the dominant factor in the stripping of stellar envelopes. we also show that lmax aligns with the lowest luminosity of single nitrogen-rich wolf-rayet stars, indicating of a change in evolutionary sequence for stars above a critical mass. from population synthesis analysis we show that the geneva evolutionary models greatly overpredict the numbers of cool sgs in the smc. we also argue that the trend of earlier average spectral types of cool sgs in lower metallicity environments represents a genuine shift to hotter temperatures. finally, we use our new bolometric luminosity measurements to provide updated bolometric corrections for cool sgs. | the luminosities of cool supergiants in the magellanic clouds, and the humphreys-davidson limit revisited |
we show how the interplay between active galactic nuclei (agns) and merger history determines whether a galaxy quenches star formation (sf) at high redshift. we first simulate, in a full cosmological context, a galaxy of total dynamical mass mvir = 1012 m⊙ at z = 2. then we systematically alter the accretion history of the galaxy by minimally changing the linear overdensity in the initial conditions. this `genetic modification' approach allows the generation of three sets of λ cdm initial conditions leading to maximum merger ratios of 1:10, 1:5 and 2:3, respectively. the changes leave the final halo mass, large-scale structure and local environment unchanged, providing a controlled numerical experiment. interaction between the agn physics and mergers in the three cases leads, respectively, to a star-forming, temporarily quenched and permanently quenched galaxy. however, the differences do not primarily lie in the black hole accretion rates, but in the kinetic effects of the merger: the galaxy is resilient against agn feedback unless its gaseous disc is first disrupted. typical accretion rates are comparable in the three cases, falling below 0.1 m⊙ yr-1, equivalent to around 2 per cent of the eddington rate or 10-3 times the pre-quenching star formation rate, in agreement with observations. this low level of black hole accretion can be sustained even when there is insufficient dense cold gas for sf. conversely, supernova feedback is too distributed to generate outflows in high-mass systems, and cannot maintain quenching over periods longer than the halo gas cooling time. | how to quench a galaxy |
the effects of rotation on stellar evolution are particularly important at low metallicity, when mass loss by stellar winds diminishes and the surface enrichment due to rotational mixing becomes relatively more pronounced than at high metallicities. here we investigate the impact of rotation and metallicity on stellar evolution. using similar physics as in our previous large grids of models at z = 0.002 and z = 0.014, we compute stellar evolution models with the geneva code for rotating and nonrotating stars with initial masses (mini) between 1.7 and 120 m⊙ and z = 0.0004 (1/35 solar). this is comparable to the metallicities of the most metal poor galaxies observed so far, such as i zw 18. concerning massive stars, both rotating and nonrotating models spend most of their core-helium burning phase with an effective temperature higher than 8000 k. stars become red supergiants only at the end of their lifetimes, and few red supergiants are expected. our models predict very few to no classical wolf-rayet stars as a results of weak stellar winds at low metallicity. the most massive stars end their lifetimes as luminous blue supergiants or luminous blue variables, a feature that is not predicted by models with higher initial metallicities. interestingly, due to the behavior of the intermediate convective zone, the mass domain of stars producing pair-instability supernovae is smaller at z = 0.0004 than at z = 0.002. we find that during the main sequence (ms) phase, the ratio between nitrogen and carbon abundances (n/c) remains unchanged for nonrotating models. however, n/c increases by factors of 10-20 in rotating models at the end of the ms. cepheids coming from stars with mini > 4 - 6 m⊙ are beyond the core helium burning phase and spend little time in the instability strip. since they would evolve towards cooler effective temperatures, these cepheids should show an increase of the pulsation period as a function of age. the stellar evolution tracks and tables are only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/627/a24 | grids of stellar models with rotation. iv. models from 1.7 to 120 m⊙ at a metallicity z = 0.0004 |
we present a sample of type icn supernovae (sne icn), a newly discovered class of transients characterized by their interaction with h- and he-poor circumstellar material (csm). this sample is the largest collection of sne icn to date and includes observations of two published objects (sn 2019hgp and sn 2021csp) and two objects not yet published in the literature (sn 2019jc and sn 2021ckj). the sne icn display a range of peak luminosities, rise times, and decline rates, as well as diverse late-time spectral features. to investigate their explosion and progenitor properties, we fit their bolometric light curves to a semianalytical model consisting of luminosity inputs from circumstellar interaction and radioactive decay of 56ni. we infer low ejecta masses (≲2 m ⊙) and 56ni masses (≲0.04 m ⊙) from the light curves, suggesting that normal stripped-envelope supernova (sesn) explosions within a dense csm cannot be the underlying mechanism powering sne icn. additionally, we find that an estimate of the star formation rate density at the location of sn 2019jc lies at the lower end of a distribution of sesne, in conflict with a massive star progenitor of this object. based on its estimated ejecta mass, 56ni mass, and explosion site properties, we suggest a low-mass, ultra-stripped star as the progenitor of sn 2019jc. for other sne icn, we suggest that a wolf-rayet star progenitor may better explain their observed properties. this study demonstrates that multiple progenitor channels may produce sne icn and other interaction-powered transients. | the diverse properties of type icn supernovae point to multiple progenitor channels |
we reanalyse observations of type ia supernovae (sne) and cepheids used in the local determination of the hubble constant and find strong evidence that sn standardization in the calibration sample (galaxies with observed cepheids) requires a steeper slope of the colour correction than in the cosmological sample (galaxies in the hubble flow). the colour correction in the calibration sample is consistent with being entirely due to an extinction correction due to dust with properties similar to those of the milky way (rb ≈ 4.6 ± 0.4) and there is no evidence for intrinsic scatter in the sn peak magnitudes. an immediate consequence of this finding is that the local measurement of the hubble constant becomes dependent on the choice of sn reference colour, i.e. the colour of an unreddened sn. specifically, the hubble constant inferred from the same observations decreases gradually with the reference colour assumed in the sn standardization. we recover the hubble constant measured by sh0es for the standard choice of reference colour (salt2 colour parameter c = 0), while for a reference colour that coincides with the blue end of the observed sn colour distribution (c ≈ -0.13), the hubble constant from planck observations of the cosmic microwave background (cmb) [assuming a flat lambda cold dark matter (λcdm) cosmological model] is recovered. these results are intriguing in that they may provide an avenue for resolving the hubble tension. however, since there is no obvious physical basis for the differences in colour corrections in the two sn samples, the origin of these requires further investigation. | intrinsic tension in the supernova sector of the local hubble constant measurement and its implications |
we study star cluster formation at low metallicities of z/z⊙ = 10-4-10-1 using three-dimensional hydrodynamics simulations. particular emphasis is put on how the stellar mass distribution is affected by the cosmic microwave background radiation (cmb), which sets the temperature floor to the gas. starting from the collapse of a turbulent cloud, we follow the formation of a protostellar system resolving ~au scale. in relatively metal-enriched cases of z/z⊙ ≳ 10-2, where the mass function resembles the present-day one in the absence of cmb, high-temperature cmb suppresses cloud fragmentation and reduces the number of low-mass stars, making the mass function more top-heavy than in the cases without cmb heating at z ≳ 10. in lower-metallicity cases with z/z⊙ ≲ 10-3, where the gas temperature is higher than the cmb value due to inefficient cooling, the cmb has only a minor impact on the mass distribution, which is top-heavy, regardless of the redshift. in cases either with a low metallicity of z/z⊙ ≲ 10-2 or at a high redshift z ≳ 10, the mass spectrum consists of a low-mass salpeter-like component, peaking at 0.1 m⊙, and a top-heavy component with 10-50 m⊙, with the fraction in the latter increasing with increasing redshift. in galaxies forming at z ≳ 10, the major targets of the future instruments including jwst, cmb heating makes the stellar mass function significantly top-heavy, enhancing the number of supernova explosions by a factor of 1.4 (2.8) at z = 10 (20, respectively) compared to the prediction by chabrier initial mass function when z/z⊙ = 0.1. | impact of the cosmic background radiation on the initial mass function of metal-poor stars |
common envelope evolution is a fundamental ingredient in our understanding of the formation of close binary stars containing compact objects that include the progenitors of type ia supernovae, short gamma-ray bursts, and most stellar gravitational wave sources. to predict the outcome of common envelope evolution, we still rely to a large degree on a simplified energy conservation equation. unfortunately, this equation contains a theoretically rather poorly constrained efficiency parameter (αce) and, even worse, it is unclear if energy sources in addition to orbital energy (such as recombination energy) contribute to the envelope ejection process. in previous works, we reconstructed the evolution of observed populations of post-common envelope binaries (pcebs) consisting of white dwarfs with main-sequence star companions and found indications that the efficiency is rather small (αce ≃ 0.2-0.3) and that extra energy sources are only required in very few cases. here, we used the same reconstruction tool to investigate the evolutionary history of a sample of observed pcebs with brown dwarf companions. in contrast to previous works, we found that the evolution of observationally well-characterized pcebs with brown dwarf companions can be understood assuming a low common envelope efficiency (αce = 0.24-0.41), similar to that required to understand pcebs with main-sequence star companions, and that contributions from recombination energy are not required. we conclude that the vast majority of pcebs form from common envelope evolution that can be parametrized with a small efficiency and without taking into account additional energy sources. | close detached white dwarf + brown dwarf binaries: further evidence for low values of the common envelope efficiency |
the accuracy of einstein's equivalence principle (eep) can be tested with the observed time delays between correlated particles or photons that are emitted from astronomical sources. assuming as a lower limit that the time delays are caused mainly by the gravitational potential of the milky way, we prove that fast radio bursts (frbs) of cosmological origin can be used to constrain the eep with high accuracy. taking frb 110220 and two possible frb/gamma-ray burst (grb) association systems (frb/grb 101011a and frb/grb 100704a) as examples, we obtain a strict upper limit on the differences of the parametrized post-newtonian parameter γ values as low as [γ (1.23 ghz )-γ (1.45 ghz )] <4.36 ×10-9. this provides the most stringent limit up to date on the eep through the relative differential variations of the γ parameter at radio energies, improving by 1 to 2 orders of magnitude the previous results at other energies based on supernova 1987a and grbs. | testing einstein's equivalence principle with fast radio bursts |
we report the results of our observing campaign on grb 140903a, a nearby (z = 0.351) short-duration (t 90 ∼ 0.3 s) gamma-ray burst discovered by swift. we monitored the x-ray afterglow with chandra up to 15 days after the burst and detected a steeper decay of the x-ray flux after tj≈ 1 day. continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. by using the standard fireball model to describe the afterglow evolution, we derive a jet opening angle θj≈ 5° and a collimation-corrected total energy release e ≈ 2 × {10}50 erg. we further discuss the nature of the grb progenitor system. three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star formation rate of the host galaxy, and the lack of a bright supernova. we conclude that this event likely originated from a compact binary merger. | an achromatic break in the afterglow of the short grb 140903a: evidence for a narrow jet |
we study how star formation is regulated in low-mass field dwarf galaxies ( $10^5 \le m_{\star } \le 10^6 \, \mbox{m}_\mathrm{\odot }$ ), using cosmological high-resolution ( $3 \, \mathrm{pc}$ ) hydrodynamical simulations. cosmic reionization quenches star formation in all our simulated dwarfs, but three galaxies with final dynamical masses of $3 \times 10^{9} \, \mbox{m}_\mathrm{\odot }$ are subsequently able to replenish their interstellar medium by slowly accreting gas. two of these galaxies reignite and sustain star formation until the present day at an average rate of $10^{-5} \, \mbox{m}_\mathrm{\odot } \, \text{yr}^{-1}$ , highly reminiscent of observed low-mass star-forming dwarf irregulars such as leo t. the resumption of star formation is delayed by several billion years due to residual feedback from stellar winds and type ia supernovae; even at z = 0, the third galaxy remains in a temporary equilibrium with a large gas content but without any ongoing star formation. using the 'genetic modification' approach, we create an alternative mass growth history for this gas-rich quiescent dwarf and show how a small $(0.2\, \mathrm{dex})$ increase in dynamical mass can overcome residual stellar feedback, reigniting star formation. the interaction between feedback and mass build-up produces a diversity in the stellar ages and gas content of low-mass dwarfs, which will be probed by combining next-generation h i and imaging surveys. | edge: from quiescent to gas-rich to star-forming low-mass dwarf galaxies |
gravitational wave observations can be used to accurately measure the hubble constant $h_0$ and could help understand the present discrepancy between constraints from type ia supernovae and the cosmic microwave background. neutron star mergers are primarily used for this purpose as their electromagnetic emission can be used to greatly reduce measurement uncertainties. here we estimate $h_0$ using the recently observed black hole merger gw190521 and its candidate electromagnetic counterpart found by ztf using a highly eccentric explanation of the properties of gw190521. we find that the reconstructed distance of gw190521 and the redshift of the candidate host galaxy are more consistent with standard cosmology for our eccentric model than if we reconstruct the source parameters assuming no eccentricity. we obtain $h_0=88.6^{+17.1}_{-34.3}$\,km\,s$^{-1}$mpc$^{-1}$ for gw190521, and $h_0=73.4^{+6.9}_{-10.7}$\,km\,s$^{-1}$mpc$^{-1}$ in combination with the results of the neutron star merger gw170817. our results indicate that future $h_0$ computations using black hole mergers will need to account for possible eccentricity. for extreme cases, the orbital velocity of binaries in agn disks can represent a significant systematic uncertainty. | hubble constant measurement with gw190521 as an eccentric black hole merger |
four decades ago, the firm detection of an fe-k emission feature in the x-ray spectrum of the perseus cluster revealed the presence of iron in its hot intracluster medium (icm). with more advanced missions successfully launched over the last 20 years, this discovery has been extended to many other metals and to the hot atmospheres of many other galaxy clusters, groups, and giant elliptical galaxies, as evidence that the elemental bricks of life—synthesized by stars and supernovae—are also found at the largest scales of the universe. because the icm, emitting in x-rays, is in collisional ionisation equilibrium, its elemental abundances can in principle be accurately measured. these abundance measurements, in turn, are valuable to constrain the physics and environmental conditions of the type ia and core-collapse supernovae that exploded and enriched the icm over the entire cluster volume. on the other hand, the spatial distribution of metals across the icm constitutes a remarkable signature of the chemical history and evolution of clusters, groups, and ellipticals. here, we summarise the most significant achievements in measuring elemental abundances in the icm, from the very first attempts up to the era of xmm-newton, chandra, and suzaku and the unprecedented results obtained by hitomi. we also discuss the current systematic limitations of these measurements and how the future missions xrism and athena will further improve our current knowledge of the icm enrichment. | enrichment of the hot intracluster medium: observations |
core-collapse supernova (sn) explosions expose the structure and environment of massive stars at the moment of their death. we use the global fitting technique of pejcha & prieto to estimate a set of physical parameters of 19 normal sne ii, such as their distance moduli, reddenings, 56ni masses {m}{ni}, and explosion energies {e}\expfrom multicolor light curves and photospheric velocity curves. we confirm and characterize known correlations between {m}{ni} and bolometric luminosity at 50 days after the explosion, and between {m}{ni} and {e}\exp . we pay special attention to the observed distribution of {m}{ni} coming from a joint sample of 38 sne ii, which can be described as a skewed-gaussian-like distribution between 0.005 {m}⊙and 0.280 {m}⊙ , with a median of 0.031 {m}⊙ , mean of 0.046 {m}⊙ , standard deviation of 0.048 {m}⊙ , and skewness of 3.050. we use a two-sample kolmogorov-smirnov test and two-sample anderson-darling test to compare the observed distribution of {m}{ni} to results from theoretical hydrodynamical codes of core-collapse explosions with the neutrino mechanism presented in the literature. our results show that the theoretical distributions obtained from the codes tested in this work, kepler and prometheus hot bubble, are compatible with the observations irrespective of different pre-sn calibrations and different maximum mass of the progenitors. | the nickel mass distribution of normal type ii supernovae |
we investigate axisymmetric black hole (bh) formation and its gravitational wave (gw) and neutrino signals with self-consistent core-collapse supernova simulations of a non-rotating 40 m ⊙ progenitor star using the isotropic diffusion source approximation for the neutrino transport and a modified gravitational potential for general relativistic effects. we consider four different neutron star (ns) equations of state (eos): ls220, sfho, bhbλϕ, and dd2, and study the impact of the eos on bh formation dynamics and gw emission. we find that the bh formation time is sensitive to the eos from 460 to >1300 ms and is delayed in multiple dimensions for ∼100-250 ms due to the finite entropy effects. depending on the eos, our simulations show the possibility that shock revival can occur along with the collapse of the proto-neutron star (pns) to a bh. the gravitational waveforms contain four major features that are similar to previous studies but show extreme values: (1) a low-frequency signal (∼300-500 hz) from core-bounce and prompt convection, (2) a strong signal from the pns g-mode oscillation among other features, (3) a high-frequency signal from the pns inner-core convection, and (4) signals from the standing accretion shock instability and convection. the peak frequency at the onset of bh formation reaches to ∼2.3 khz. the characteristic amplitude of a 10 kpc object at peak frequency is detectable but close to the noise threshold of the advanced ligo and kagra, suggesting that the next-generation gw detector will need to improve the sensitivity at the khz domain to better observe stellar-mass bh formation from core-collapse supernovae or failed supernovae. | equation of state dependent dynamics and multi-messenger signals from stellar-mass black hole formation |
we present a simple model for the response of a dissipationless spherical system to an instantaneous mass change at its centre, describing the formation of flat cores in dark matter haloes and ultra-diffuse galaxies (udgs) from feedback-driven outflow episodes in a specific mass range. this model generalizes an earlier simplified analysis of an isolated shell into a system with continuous density, velocity, and potential profiles. the response is divided into an instantaneous change of potential at constant velocities due to a given mass-loss or mass-gain, followed by energy-conserving relaxation to a new jeans equilibrium. the halo profile is modelled by a two-parameter function with a variable inner slope and an analytic potential profile, which enables determining the associated kinetic energy at equilibrium. the model is tested against nihao cosmological zoom-in simulations, where it successfully predicts the evolution of the inner dark matter profile between successive snapshots in about 75 per cent of the cases, failing mainly in merger situations. this model provides a simple understanding of the formation of dark matter halo cores and udgs by supernova-driven outflows, and a useful analytic tool for studying such processes. | a model for core formation in dark matter haloes and ultra-diffuse galaxies by outflow episodes |
we study the growth of the explosion energy after shock revival in neutrino-driven explosions in two and three dimensions (2d/3d) using multi-group neutrino hydrodynamics simulations of an 11.2 m⊙ star. the 3d model shows a faster and steadier growth of the explosion energy and already shows signs of subsiding accretion after one second. by contrast, the growth of the explosion energy in 2d is unsteady, and accretion lasts for several seconds as confirmed by additional long-time simulations of stars of similar masses. appreciable explosion energies can still be reached, albeit at the expense of rather high neutron star masses. in 2d, the binding energy at the gain radius is larger because the strong excitation of downward-propagating g modes removes energy from the freshly accreted material in the downflows. consequently, the mass outflow rate is considerably lower in 2d than in 3d. this is only partially compensated by additional heating by outward-propagating acoustic waves in 2d. moreover, the mass outflow rate in 2d is reduced because much of the neutrino energy deposition occurs in downflows or bubbles confined by secondary shocks without driving outflows. episodic constriction of outflows and vertical mixing of colder shocked material and hot, neutrino-heated ejecta due to rayleigh-taylor instability further hamper the growth of the explosion energy in 2d. further simulations will be necessary to determine whether these effects are generic over a wider range of supernova progenitors. | the dynamics of neutrino-driven supernova explosions after shock revival in 2d and 3d |
we apply gaussian processes (gp) in order to impose constraints on teleparallel gravity and its f(t) extensions. we use available h(z) observations from (i) cosmic chronometers data (cc); (ii) supernova type ia (sn) data from the compressed pantheon release together with the candels and clash multi-cycle treasury programs; and (iii) baryonic acoustic oscillation (bao) datasets from the sloan digital sky survey. for the involved covariance functions, we consider four widely used choices, namely the square exponential, cauchy, matérn and rational quadratic kernels, which are consistent with one another within 1σ confidence levels. specifically, we use the gp approach to reconstruct a model-independent determination of the hubble constant h0, for each of these kernels and dataset combinations. these analyses are complemented with three recently announced literature values of h0, namely (i) riess ${h}_{0}^{\mathrm{r}}=74.22{\pm}1.82\enspace {\mathrm{k}\mathrm{m}\enspace \mathrm{s}}^{-1}\enspace {\mathrm{m}\mathrm{p}\mathrm{c}}^{-1}$ ; (ii) h0licow collaboration ${h}_{0}^{\text{hw}}=73.{3}_{-1.8}^{+1.7}\enspace {\mathrm{k}\mathrm{m}\enspace \mathrm{s}}^{-1}\enspace {\mathrm{m}\mathrm{p}\mathrm{c}}^{-1}$ ; and (iii) carnegie-chicago hubble programme ${h}_{0}^{\text{trgb}}=69.8{\pm}1.9\enspace {\mathrm{k}\mathrm{m}\enspace \mathrm{s}}^{-1}\enspace {\mathrm{m}\mathrm{p}\mathrm{c}}^{-1}$ . additionally, we investigate the transition redshift between the decelerating and accelerating cosmological phases through the gp reconstructed deceleration parameter. furthermore, we reconstruct the model-independent evolution of the dark energy equation of state, and finally reconstruct the allowed f(t) functions. as a result, the λcdm model lies inside the allowed region at 1σ in all the examined kernels and datasets, however a negative slope for f(t) versus t is slightly favoured. | constraining teleparallel gravity through gaussian processes |
we present three-dimensional radiation-hydrodynamical simulations of the impact of stellar winds, photoelectric heating, photodissociating and photoionizing radiation, and supernovae on the chemical composition and star formation in a stratified disc model. this is followed by a sink-based model for star clusters with populations of individual massive stars. stellar winds and ionizing radiation regulate the star formation rate at a factor of ∼10 below the simulation with only supernova feedback due to their immediate impact on the ambient interstellar medium after star formation. ionizing radiation (with winds and supernovae) significantly reduces the ambient densities for most supernova explosions to ρ < 10-25 g cm-3, compared to 10-23g cm-3 for the model with only winds and supernovae. radiation from massive stars reduces the amount of molecular hydrogen and increases the neutral hydrogen mass and volume filling fraction. only this model results in a molecular gas depletion time-scale of 2 gyr and shows the best agreement with observations. in the radiative models, the hα emission is dominated by radiative recombination as opposed to collisional excitation (the dominant emission in non-radiative models), which only contributes ∼1-10 per cent to the total hα emission. individual massive stars (m ≥ 30 m⊙) with short lifetimes are responsible for significant fluctuations in the hα luminosities. the corresponding inferred star formation rates can underestimate the true instantaneous star formation rate by a factor of ∼10. | the silcc project - iv. impact of dissociating and ionizing radiation on the interstellar medium and hα emission as a tracer of the star formation rate |
carbon and oxygen burning reactions, in particular, c 12 +c 12 fusion, are important for the understanding and interpretation of the late phases of stellar evolution as well as the ignition and nucleosynthesis in cataclysmic binary systems such as type ia supernovae and x-ray superbursts. a new measurement of this reaction has been performed at the university of notre dame using particle-γ coincidence techniques with sand (a silicon detector array) at the high-intensity 5u pelletron accelerator. new results for c 12 +c 12 fusion at low energies relevant to nuclear astrophysics are reported. they show strong disagreement with a recent measurement using the indirect trojan horse method. the impact on the carbon burning process under astrophysical scenarios will be discussed. | new measurement of c 12 +c 12 fusion reaction at astrophysical energies |
recent studies on direct imaging of type ii core-collapse supernova progenitors indicate a possible threshold around mzams ∼ 16-20 m⊙, where red supergiants (rsg) with larger birth masses do not appear to result in supernova explosions and instead implode directly into a black hole. in this study, we argue that it is not a coincidence that this threshold closely matches the critical transition of central carbon burning in massive stars from the convective to radiative regime. in lighter stars, carbon burns convectively in the centre and result in compact final pre-supernova cores that are likely to result in explosions, while in heavier stars after the transition, it burns as a radiative flame and the stellar cores become significantly harder to explode. using the kepler code we demonstrate the sensitivity of this transition to the rate of 12c(α, γ)16o reaction and the overshoot mixing efficiency, and we argue that the upper mass limit of exploding rsg could be employed to constrain uncertain input physics of massive stellar evolution calculations. the initial mass corresponding to the central carbon burning transition range from 14 to 26 m⊙ in recently published models from various groups and codes, and only a few are in agreement with the estimates inferred from direct imaging studies. | missing red supergiants and carbon burning |
the final collapse of the cores of massive stars can lead to a wide variety of outcomes in terms of electromagnetic and kinetic energies, nucleosynthesis, and remnants. the association of this wide spectrum of explosion and remnant types with the properties of the progenitors remains an open issue. the rotation and magnetic fields in wolf-rayet stars of subsolar metallicity may explain extreme events such as superluminous supernovae and gamma-ray bursts powered by proto-magnetars or collapsars. continuing with numerical studies of magnetorotational core collapse, including detailed neutrino physics, we focus on progenitors with zero-age main-sequence masses in the range between 5 and 39 ${\rm m}_{\odot }$. the pre-collapse stars are 1d models employing prescriptions for the effects of rotation and magnetic fields. eight of the 10 stars we consider are the results of chemically homogeneous evolution owing to enhanced rotational mixing . all but one of them produce explosions driven by neutrino heating (more likely for low-mass progenitors up to 8 ${\rm m}_{\odot }$) and non-spherical flows or by magnetorotational stresses (more frequent above 26 ${\rm m}_{\odot }$). in most of them and for the one non-exploding model, ongoing accretion leads to black hole formation. rapid rotation makes subsequent collapsar activity plausible. models not forming black holes show proto-magnetar-driven jets. conditions for the formation of nickel are more favourable in magnetorotationally driven models, although our rough estimates fall short of the requirements for extremely bright events if these are powered by radioactive decay. however, the approximate light curves of our models suggest that a proto-magnetar or black hole spin-down may fuel luminous transients (with peak luminosities $\sim 10^{43-44}\, \textrm {erg}$). | magnetorotational core collapse of possible gamma-ray burst progenitors - iv. a wider range of progenitors |
in the context of a ghost free f(r , g) model, we present a non-singular cosmological scenario in which the universe initially contracts through an ekpyrotic phase having a bouncing like behaviour, and following the bounce, it smoothly transits to a matter or radiation like deceleration era which is further smoothly connected to the dark energy era at present epoch. the ghost free character of the model is ensured by the presence of a lagrange multiplier, and we consider the gauss-bonnet (gb) coupling function in such a way that it gets compatible with the event gw170817. using suitable reconstruction technique, we obtain the non-trivial scalar field potential as well as the gb coupling function. such scalar potential and gb coupling function source a smooth unified scenario from an ekpyrotic bounce to the dark energy era with an intermediate deceleration era. the occurrence of ekpyrotic contraction phase justifies the resolution of the anisotropic problem (also known as bkl instability) in the background evolution. consequently we determine the background hubble parameter and the corresponding effective equation of state parameter, and discussed several qualitative features of the model. the hubble radius shows an asymmetric behaviour around the bounce, in particular, the evolution of the hubble radius leads to the generation era of the primordial perturbation modes far before the bounce in the deep sub-hubble regime. accordingly we perform the scalar and tensor perturbation evolution in the present context, and as a result, the scalar power spectrum at large scale modes is found to be problematic. thus an extended scenario is proposed where we consider a pre-ekpyrotic phase having the equation of state parameter is less than unity, and re-examine the scalar and tensor power spectra, on large scales that cross the hubble radius during the pre-ekpyrotic stage. in this regard, the gb coupling function shows considerable effects in reducing the tensor to scalar ratio compared to the case where the gb coupling is absent. furthermore the dark energy epoch is consistent with the planck +sne +bao data. | towards a smooth unification from an ekpyrotic bounce to the dark energy era |
binary population synthesis (bps) employs prescriptions to predict final fates, explosion or implosion, and remnant masses based on one or two stellar parameters at the evolutionary cutoff imposed by the code, usually at or near central carbon ignition. in doing this, bps disregards the integral role late-stage evolution plays in determining the final fate, remnant type, and remnant mass within the neutrino-driven explosion paradigm. to highlight differences between a popular prescription, which relies only on the core and final stellar mass and emerging methods, which rely on a star's presupernova core structure, we generate a series of compact object distributions using three different methods for a sample population of single and binary stars computed in bpass. the first method estimates remnant mass based on a star's carbon-oxygen (co) core mass and final total mass. the second method uses the presupernova core structure based on recent bare co-core models combined with a parameterized explosion criterion to first determine final fate and remnant type, then remnant mass. the third method associates presupernova helium-core masses with remnant masses determined from public explosion models which rely implicitly on core structure. we find that the core-/final mass-based prescription favours lower mass remnants, including a large population of mass gap black holes, and predicts neutron star masses which span a wide range, whereas the structure-based prescriptions favour slightly higher mass remnants, mass gap black holes only as low as 3.5 m⊙, and predict ns mass distributions which cluster in a narrow range. | comparing compact object distributions from mass- and presupernova core structure-based prescriptions |
self-interacting dark matter provides a promising alternative for the cold dark matter paradigm to solve potential small-scale galaxy formation problems. nearly all self-interacting dark matter simulations so far have considered only elastic collisions. here we present simulations of a galactic halo within a generic inelastic model using a novel numerical implementation in the arepo code to study arbitrary multistate inelastic dark matter scenarios. for this model we find that inelastic self-interactions can: (i) create larger subhalo density cores compared to elastic models for the same cross-section normalization; (ii) lower the abundance of satellites without the need for a power spectrum cut-off; (iii) reduce the total halo mass by about 10{{ per cent}}; (iv) inject the energy equivalent of o(100) million type ii supernovae in galactic haloes through level de-excitation; (v) avoid the gravothermal catastrophe due to removal of particles from halo centres. we conclude that a ∼5 times larger elastic cross-section is required to achieve the same central density reduction as the inelastic model. this implies that well-established constraints on self-interacting cross-sections have to be revised if inelastic collisions are the dominant mode. in this case significantly smaller cross-sections can achieve the same core density reduction thereby increasing the parameter space of allowed models considerably. | evaporating the milky way halo and its satellites with inelastic self-interacting dark matter |
the surprising jwst discovery of a quiescent, low-mass (m ⋆ = 108.7 m ⊙) galaxy at redshift z = 7.3 (jades-gs-z7-01-qu) represents a unique opportunity to study the imprint of feedback processes on early galaxy evolution. we build a sample of 130 low-mass (m ⋆ ≲ 109.5 m ⊙) galaxies from the serra cosmological zoom-in simulations, which show a feedback-regulated, bursty star formation history (sfh). the fraction of time spent in an active phase increases with the stellar mass from f duty ≈ 0.6 at m ⋆ ≈ 107.5 m ⊙ to ≈0.99 at m ⋆ ≥ 109 m ⊙, and it is in agreement with the value f duty ≈ 0.75 estimated for jades-gs-z7-01-qu. on average, 30% of the galaxies are quiescent in the range 6 < z < 8.4; they become the dominant population at m ⋆ ≲ 108.3 m ⊙. however, none of these quiescent systems matches the spectral energy distribution of jades-gs-z7-01-qu, unless their sfh is artificially truncated a few myr after the main star formation peak. as supernova feedback can only act on a longer timescale (≳30 myr), this implies that the observed abrupt quenching must be caused by a faster physical mechanism, such as radiation-driven winds from young massive stars and/or an active galactic nucleus. | quiescent low-mass galaxies observed by jwst in the epoch of reionization |
during the zwicky transient facility (ztf) phase i operations, 78 hydrogen-poor superluminous supernovae (slsne-i) were discovered in less than 3 yr, constituting the largest sample from a single survey. this paper (paper i) presents the data, including the optical/uv light curves and classification spectra, while paper ii in this series will focus on the detailed analysis of the light curves and modeling. our photometry is primarily taken by ztf in the g, r, and i bands, and with additional data from other ground-based facilities and swift. the events of our sample cover a redshift range of z = 0.06 - 0.67, with a median and 1σ error (16% and 84% percentiles) of ${z}_{\mathrm{med}}={0.265}_{-0.135}^{+0.143}$ . the peak luminosity covers -22.8 mag ≤ mg,peak ≤ -19.8 mag, with a median value of $-{21.48}_{-0.61}^{+1.13}$ mag. the light curves evolve slowly with a mean rest-frame rise time of t rise = 41.9 ± 17.8 days. the luminosity and timescale distributions suggest that low-luminosity slsne-i with a peak luminosity ~-20 mag or extremely fast-rising events (<10 days) exist, but are rare. we confirm previous findings that slowly rising slsne-i also tend to fade slowly. the rest-frame color and temperature evolution show large scatters, suggesting that the slsn-i population may have diverse spectral energy distributions. the peak rest-frame color shows a moderate correlation with the peak absolute magnitude, i.e., brighter slsne-i tend to have bluer colors. with optical and uv photometry, we construct the bolometric luminosity and derive a bolometric correction relation that is generally applicable for converting g, r-band photometry to the bolometric luminosity for slsne-i. | the hydrogen-poor superluminous supernovae from the zwicky transient facility phase i survey. i. light curves and measurements |
mapping cosmic dawn with 21-cm tomography offers an exciting new window into the era of primordial star formation. however, self-consistent implementation of both the process of star formation and the related 21-cm signal is challenging, due to the multiscale nature of the problem. in this study, we develop a flexible semi-analytical model to follow the formation of the first stars and the process of gradual transition from primordial to metal-enriched star formation. for this transition, we use different scenarios with varying time-delays (or recovery times) between the first supernovae and the formation of the second generation of stars. we use recovery times between 10 and 100 myr and find that these delays have a strong impact on the redshift at which the transition to metal-enriched star formation occurs. we then explore the effect of this transition on the 21-cm signal and find that the recovery time has a distinctive imprint in the signal. together with an improved understanding of how this time-delay relates to the properties of population iii stars, future 21-cm observations can give independent constraints on the earliest epoch of star formation. as the transition away from the primordial star formation is expected to occur at high redshifts, here we ignore the impact of x-ray and ionizing radiation, focusing on the effect of ly α photons on the 21-cm signal. | effect of the cosmological transition to metal-enriched star formation on the hydrogen 21-cm signal |
new particles coupled to the standard model can equilibrate in stellar cores if they are sufficiently heavy and strongly coupled. in this work, we investigate the astrophysical consequences of such a scenario for massive stars by incorporating new contributions to the equation of state into a state of the art stellar structure code. we focus on axions in the "cosmological triangle," a region of parameter space with 300 kev ≲ma≲2 mev , ga γ γ∼10-5 gev-1 that is not presently excluded by other considerations. we find that for axion masses ma∼me, axion production in the core drives a new stellar instability that results in explosive nuclear burning that either drives a series of mass-shedding pulsations or completely disrupts the star resulting in a new type of optical transient—an axion instability supernova. we predict that the upper black hole mass gap would be located at 37 m⊙≤m ≤107 m⊙ in these theories, a large shift down from the standard prediction, which is disfavored by the detection of the mass gap in the ligo/virgo/kagra gwtc-2 gravitational wave catalog beginning at 46-6+17 m⊙. furthermore, axion-instability supernovae are more common than pair-instability supernovae, making them excellent candidate targets for james webb space telescope. the methods presented in this work can be used to investigate the astrophysical consequences of any theory of new physics that contains heavy bosonic particles of arbitrary spin. we provide the tools to facilitate such studies. | axion instability supernovae |
understanding the astrophysical phenomena involving compact objects requires an insight about the engine behind the core-collapse supernovae (sne) and the fate of the stellar collapse of massive stars. in particular, this insight is crucial in developing an understanding of the origin and formation channels of the growing populations of the detected black hole-black hole, black hole-neutron star, and neutron star-neutron star mergers. the time-scale of convection growth may have a large effect on the strength of sn explosion and therefore also on the mass distribution of stellar remnants. we adopt new formulas for the relation between the pre-sn star properties and their remnants and check how they impact the population of double compact object (dco) mergers formed via the isolated binary evolution. the new formulas give one the ability to test a wide spectrum of assumptions on the convection growth time. in particular, the different variants allow for a smooth transition between having a deep mass gap and a remnant mass distribution filled by massive neutron stars and low-mass black holes. we present the distribution of masses, mass ratios, and the local merger rate densities of dco for the different variants of new formulas and test them together with different approaches to other highly uncertain processes. we find that the mass distribution of dco mergers is sensitive to the adopted assumption on the sn convection growth time-scale up to $m_1+m_2 \lesssim 35 \, \mathrm{m}_{\odot }$. between the two extreme tested variants the probability of compact object formation within the mass gap may differ by up to approximately two orders of magnitude. | the role of supernova convection for the lower mass gap in the isolated binary formation of gravitational wave sources |
the supernova (sn) ptf11iqb was initially classified as a type iin event caught very early after explosion. it showed narrow wolf-rayet (wr) spectral features on day 2 (as in sn 1998s and sn 2013cu), but the narrow emission weakened quickly and the spectrum morphed to resemble types ii-l and ii-p. at late times, hα exhibited a complex, multipeaked profile reminiscent of sn 1998s. in terms of spectroscopic evolution, we find that ptf11iqb was a near twin of sn 1998s, although with somewhat weaker interaction with circumstellar material (csm) at early times, and stronger interaction at late times. we interpret the spectral changes as caused by early interaction with asymmetric csm that is quickly (by day 20) enveloped by the expanding sn ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. the light curve can be matched with a simple model for csm interaction (with a mass-loss rate of roughly 10-4 m⊙ yr-1) added to the light curve of a normal sn ii-p. the underlying plateau requires a progenitor with an extended hydrogen envelope like a red supergiant at the moment of explosion, consistent with the slow wind speed (<80 km s-1) inferred from narrow hα emission. the cool supergiant progenitor is significant because ptf11iqb showed wr features in its early spectrum - meaning that the presence of such wr features does not necessarily indicate a wr-like progenitor. overall, ptf11iqb bridges sne iin with weaker pre-sn mass-loss seen in sne ii-l and ii-p, implying a continuum between these types. | ptf11iqb: cool supergiant mass-loss that bridges the gap between type iin and normal supernovae |
the present study reveals observational constraints on the coupling between dark components of anisotropic bianchi type i universe. we assume interaction between dark matter and dark energy and split the continuity equation with inclusion of interaction term $\gamma$. two scenarios have been considered (i) when coupling between dark components is constant and (ii) when it is a function of redshift ($z$). metropolis-hasting algorithm has been used to perform monte carlo markov chain (mcmc) analysis by using observational hubble data obtained from cosmic chronometric (cc) technique, cosmic microwave background (cmb) baryon acoustic oscillation (bao), pantheon compilation of supernovae type ia (snia), their joint combination and a gaussian prior on the hubble parameter $h_{0}$. it is obtained that the combination of all databases plus $h_{0}$ prior marginalized over a present dark energy density gives stringent constraints on the current value of coupling as $-0.001<\delta<0.041$ in constant coupling model and $-0.042<\delta<0.053$ in varying coupling model at 68\% confident level. in general, for both models, we found $\omega^{x}\approx -1$ and $\delta(\delta_{0})\approx 0$ which indicate that still recent data favor uncoupled $\lambda$cdm model. our estimations show that in constant coupling model $(h_{0}=73.9^{+1.5}_{-0.95}, \delta=0.023^{+0.017}_{-0.024})$ which naturally leads to consistent value of the hubble constant. this result is interesting because the previous works show that such a high value of hubble constant requires the significant value of coupling parameter $\delta$. it has been also observed that in the constant coupling model, we do not find any disagreement between the estimated $h_{0}$ and those reported by hubble space telescope (hst) and large scale structure (lss) experiments. | interacting dark sectors in anisotropic universe: observational constraints and $h_{0}$ tension |
china jinping underground laboratory (cjpl) is ideal for studying solar, geo-, and supernova neutrinos. a precise measurement of the cosmic-ray background is essential in proceeding with r&d research for these mev-scale neutrino experiments. using a 1-ton prototype detector for the jinping neutrino experiment (jne), we detected 264 high-energy muon events from a 645.2-day dataset from the first phase of cjpl (cjpl-i), reconstructed their directions, and measured the cosmic-ray muon flux to be $(3.53\pm0.22_{\rm{stat.}}\pm0.07_{\rm{sys.}})\times10^{-10}$ cm $^{-2}$ s $^{-1}$ . the observed angular distributions indicate the leakage of cosmic-ray muon background and agree with simulation data accounting for jinping mountain's terrain. a survey of muon fluxes at different laboratory locations, considering both those situated under mountains and those down mine shafts, indicates that the flux at the former is generally a factor of $(4\pm2)$ larger than at the latter, with the same vertical overburden. this study provides a convenient back-of-the-envelope estimation for the muon flux of an underground experiment. * supported in part by the national natural science foundation of china (11620101004, 11475093), the key laboratory of particle & radiation imaging (tsinghua university), the cas center for excellence in particle physics (ccepp), and guangdong basic and applied basic research foundation (2019a1515012216). portion of this work performed at brookhaven national laboratory is supported in part by the united states department of energy (de-sc0012704) | muon flux measurement at china jinping underground laboratory |
efficient thermalization of overlapping supernovae within star-forming galaxies may produce a supernova-heated fluid that drives galactic winds. for fiducial assumptions about the time-scale for cloud shredding from high-resolution simulations (which neglect magnetic fields), we show that cool clouds with temperature from tc ∼ 102-104 k seen in emission and absorption in galactic winds cannot be accelerated to observed velocities by the ram pressure of a hot wind. taking into account both the radial structure of the hot flow and gravity, we show that this conclusion holds over a wide range of galaxy, cloud and hot wind properties. this finding calls into question the prevailing picture whereby the cool atomic gas seen in galactic winds is entrained and accelerated by the hot flow. given these difficulties with ram pressure acceleration, we discuss alternative models for the origin of high-velocity cool gas outflows. another possibility is that magnetic fields in cool clouds are sufficiently important that they prolong the cloud's life. for tc = 103 k and 104 k clouds, we show that if conductive evaporation can be neglected, the cloud shredding time-scale must be ∼15 and 5 times longer, respectively, than the values from hydrodynamical simulations in order for cool cloud velocities to reach those seen in observations. | entrainment in trouble: cool cloud acceleration and destruction in hot supernova-driven galactic winds |
we study the final fate of a very massive star by performing full general relativistic (gr), three-dimensional (3d) simulation with three-flavour multi-energy neutrino transport. utilizing a 70 solar mass zero-metallicity progenitor, we self-consistently follow the radiation-hydrodynamics from the onset of gravitational core-collapse until the second collapse of the proto-neutron star (pns), leading to black hole (bh) formation. our results show that the bh formation occurs at a post-bounce time of tpb ∼ 300 ms for the 70 m⊙ star. this is significantly earlier than those in the literature where lower mass progenitors were employed. at a few ∼10 ms before bh formation, we find that the stalled bounce shock is revived by intense neutrino heating from the very hot pns, which is aided by violent convection behind the shock. in the context of 3d-gr core-collapse modelling with multi-energy neutrino transport, our numerical results present the first evidence to validate a fallback bh formation scenario of the 70 m⊙ star. | a full general relativistic neutrino radiation-hydrodynamics simulation of a collapsing very massive star and the formation of a black hole |
the current hubble constant tension is usually presented by comparing constraints on h0 only. however, the postrecombination background cosmic evolution is determined by two parameters in the standard λcdm model, the hubble constant (h0) and today's matter energy fraction (ωm). if we therefore compare all constraints individually in the h0-ωm plane, (1) various constraints can be treated as independently as possible, (2) single-sided constraints are easier to consider, (3) compatibility among different constraints can be viewed in a more robust way, (4) the model dependence of each constraint is clear, and (5) whether or not a nonstandard model is able to reconcile all constraints in tension can be seen more effectively. we perform a systematic comparison of different constraints in the h0-ωm space based on a flat λcdm model, treating them as separately as possible. constraints along different degeneracy directions consistently overlap in one region of the space, with the local measurement from cepheid variable-calibrated supernovae being the most outlying, followed by the time-delay strong-lensing result. considering the possibility that some nonstandard physics may reconcile the constraints, we provide a general discussion of nonstandard models with modifications at high, mid, or low redshifts and the effect of local environmental factors. due to the different responses of individual constraints to a modified model, it is not easy for nonstandard models to reconcile all constraints if none of them have unaccounted-for systematic effects. | investigating the hubble constant tension: two numbers in the standard cosmological model |
among the milky way satellites discovered in the past three years, triangulum ii has presented the most difficulty in revealing its dynamical status. kirby et al. identified it as the most dark-matter-dominated galaxy known, with a mass-to-light ratio within the half-light radius of {3600}-2100+3500 {m}⊙{l}⊙ -1. on the other hand, martin et al. measured an outer velocity dispersion that is 3.5 ± 2.1 times larger than the central velocity dispersion, suggesting that the system might not be in equilibrium. from new multi-epoch keck/deimos measurements of 13 member stars in triangulum ii, we constrain the velocity dispersion to be {σ }v< 3.4 km s-1 (90% c.l.). our previous measurement of {σ }v, based on six stars, was inflated by the presence of a binary star with variable radial velocity. we find no evidence that the velocity dispersion increases with radius. the stars display a wide range of metallicities, indicating that triangulum ii retained supernova ejecta and therefore possesses, or once possessed, a massive dark matter halo. however, the detection of a metallicity dispersion hinges on the membership of the two most metal-rich stars. the stellar mass is lower than galaxies of similar mean stellar metallicity, which might indicate that triangulum ii is either a star cluster or a tidally stripped dwarf galaxy. detailed abundances of one star show heavily depressed neutron-capture abundances, similar to stars in most other ultra-faint dwarf galaxies but unlike stars in globular clusters. the data presented herein were obtained at the w. m. keck observatory, which is operated as a scientific partnership among the california institute of technology, the university of california and the national aeronautics and space administration. the observatory was made possible by the generous financial support of the w. m. keck foundation. | triangulum ii. not especially dense after all |
gravitational-wave (gw) catalogs are rapidly increasing in number, allowing for statistical analyses of the population of compact binaries. nonetheless, gw inference of cosmology has typically relied on additional electromagnetic counterparts or galaxy catalogs. i present a new probe of cosmological modifications of general relativity with gw data only. i focus on deviations of the gw luminosity distance constrained with the astrophysical population of binary black holes (bbhs). the three key observables are 1) the number of events as a function of luminosity distance, 2) the stochastic gw background of unresolved binaries and 3) the location of any feature in the source mass distribution, such as the pair instability supernova (pisn) gap. modifications of the gw luminosity distance are a priori degenerate with the unknown evolution of the merger rate and source masses. however, a large damping of the gw amplitude predicts a reduction of the events and lowering of the edges of the pisn gap with redshift that is against standard astrophysical expectations. applying a hierarchical bayesian analysis to the current ligo-virgo catalog (gwtc-2), the strongest constraints to date are placed on deviations from the gw luminosity distance, finding cm = -3.2-2.0+3.4 at 68% c.l., which is ∼10 times better than multi-messenger gw170817 bounds. these modifications also affect the determination of the bbh masses, which is crucial to accommodate the high-mass binary gw190521 away from the pisn gap. in this analysis it is found that the maximum mass of 99% of the population shifts to lower masses with increased uncertainty, m99% = 46.2-9.1+11.4 m⊙ at 68% c.l. testing gravity at large scales with the population of bbhs will become increasingly relevant with future catalogs, providing an independent and self-contained test of the standard cosmological model. | hearing gravity from the cosmos: gwtc-2 probes general relativity at cosmological scales |
simulations of type ia supernovae (sne ia) surveys are a critical tool for correcting biases in the analysis of sne ia to infer cosmological parameters. large-scale monte carlo simulations include a thorough treatment of observation history, measurement noise, intrinsic scatter models, and selection effects. in this letter, we improve simulations with a robust technique to evaluate the underlying populations of sn ia color and stretch that correlate with luminosity. in typical analyses, the standardized sn ia brightness is determined from linear “tripp” relations between the light curve color and luminosity and between stretch and luminosity. however, this solution produces hubble residual biases because intrinsic scatter and measurement noise result in measured color and stretch values that do not follow the tripp relation. we find a 10σ bias (up to 0.3 mag) in hubble residuals versus color and 5σ bias (up to 0.2 mag) in hubble residuals versus stretch in a joint sample of 920 spectroscopically confirmed sn ia from ps1, snls, sdss, and several low-z surveys. after we determine the underlying color and stretch distributions, we use simulations to predict and correct the biases in the data. we show that removing these biases has a small impact on the low-z sample, but reduces the intrinsic scatter σ int from 0.101 to 0.083 in the combined ps1, snls, and sdss sample. past estimates of the underlying populations were too broad, leading to a small bias in the equation of state of dark energy w of δw = 0.005. | measuring type ia supernova populations of stretch and color and predicting distance biases |
aims: we perform a comprehensive study of the total mass distribution of the galaxy cluster rxc j2248.7-4431 (z = 0.348) with a set of high-precision strong lensing models, which take advantage of extensive spectroscopic information on many multiply lensed systems. in the effort to understand and quantify inherent systematics in parametric strong lensing modelling, we explore a collection of 22 models in which we use different samples of multiple image families, different parametrizations of the mass distribution and cosmological parameters.methods: as input information for the strong lensing models, we use the cluster lensing and supernova survey with hubble (clash) imaging data and spectroscopic follow-up observations, with the visible multi-object spectrograph (vimos) and multi unit spectroscopic explorer (muse) on the very large telescope (vlt), to identify and characterize bona fide multiple image families and measure their redshifts down to mf814w ≃ 26. a total of 16 background sources, over the redshift range 1.0-6.1, are multiply lensed into 47 images, 24 of which are spectroscopically confirmed and belong to ten individual sources. these also include a multiply lensed lyman-α blob at z = 3.118. the cluster total mass distribution and underlying cosmology in the models are optimized by matching the observed positions of the multiple images on the lens plane. bayesian markov chain monte carlo techniques are used to quantify errors and covariances of the best-fit parameters.results: we show that with a careful selection of a large sample of spectroscopically confirmed multiple images, the best-fit model can reproduce their observed positions with a rms scatter of 0.̋3 in a fixed flat λcdm cosmology, whereas the lack of spectroscopic information or the use of inaccurate photometric redshifts can lead to biases in the values of the model parameters. we find that the best-fit parametrization for the cluster total mass distribution is composed of an elliptical pseudo-isothermal mass distribution with a significant core for the overall cluster halo and truncated pseudo-isothermal mass profiles for the cluster galaxies. we show that by adding bona fide photometric-selected multiple images to the sample of spectroscopic families, one can slightly improve constraints on the model parameters. in particular, we find that the degeneracy between the lens total mass distribution and the underlying geometry of the universe, which is probed via angular diameter distance ratios between the lens and sources and the observer and sources, can be partially removed. allowing cosmological parameters to vary together with the cluster parameters, we find (at 68% confidence level) ωm = 0.25+ 0.13-0.16 and w = -1.07+ 0.16-0.42 for a flat λcdm model, and ωm = 0.31+ 0.12-0.13 and ωλ = 0.38+ 0.38-0.27 for a universe with w = -1 and free curvature. finally, using toy models mimicking the overall configuration of multiple images and cluster total mass distribution, we estimate the impact of the line-of-sight mass structure on the positional rms to be 0.̋3 ± 0. we argue that the apparent sensitivity of our lensing model to cosmography is due to the combination of the regular potential shape of rxc j2248, a large number of bona fide multiple images out to z = 6.1, and a relatively modest presence of intervening large-scale structure, as revealed by our spectroscopic survey. | clash-vlt: a highly precise strong lensing model of the galaxy cluster rxc j2248.7-4431 (abell s1063) and prospects for cosmography |
we present a broadband spectrum of gravitational waves (gws) from core-collapse supernovae (ccsne) sourced by neutrino emission asymmetries for a series of full 3d simulations. the associated gw strain probes the long-term secular evolution of ccsne and small-scale turbulent activity and provides insight into the geometry of the explosion. for nonexploding models, both the neutrino luminosity and the neutrino gravitational waveform will encode information about the spiral sasi. the neutrino memory will be detectable for a wide range of progenitor masses for a galactic event. our results can be used to guide near-future decihertz and long-baseline gw detection programs, including aligo, the einstein telescope, and decigo. | gravitational waves from neutrino emission asymmetries in core-collapse supernovae |
we apply deep recurrent neural networks, which are capable of learning complex sequential information, to classify supernovae (code available at https://github.com/adammoss/supernovae). the observational time and filter fluxes are used as inputs to the network, but since the inputs are agnostic, additional data such as host galaxy information can also be included. using the supernovae photometric classification challenge (spcc) data, we find that deep networks are capable of learning about light curves, however the performance of the network is highly sensitive to the amount of training data. for a training size of 50% of the representational spcc data set (around 104 supernovae) we obtain a type-ia versus non-type-ia classification accuracy of 94.7%, an area under the receiver operating characteristic curve auc of 0.986 and an spcc figure-of-merit f 1 = 0.64. when using only the data for the early-epoch challenge defined by the spcc, we achieve a classification accuracy of 93.1%, auc of 0.977, and f 1 = 0.58, results almost as good as with the whole light curve. by employing bidirectional neural networks, we can acquire impressive classification results between supernovae types i, ii and iii at an accuracy of 90.4% and auc of 0.974. we also apply a pre-trained model to obtain classification probabilities as a function of time and show that it can give early indications of supernovae type. our method is competitive with existing algorithms and has applications for future large-scale photometric surveys. | deep recurrent neural networks for supernovae classification |
milky way (mw) satellites reside within dark matter (dm) subhalos with a broad distribution of circular velocity profiles. this diversity is enhanced with the inclusion of ultrafaint satellites, which seemingly have very high dm densities, albeit with large systematic uncertainties. we argue that if confirmed, this large diversity in the mw satellite population poses a serious test for the structure formation theory with possible implications for the dm nature. for the cold dark matter model, the diversity might be a signature of the combined effects of subhalo tidal disruption by the mw disk and strong supernova feedback. for models with a dwarf-scale cutoff in the power spectrum, the diversity is a consequence of the lower abundance of dwarf-scale halos. this diversity is most challenging for self-interacting dark matter (sidm) models with cross sections σ /mχ≳1 cm2 g-1 where subhalos have too low densities to explain the ultrafaint galaxies. we propose a novel solution to explain the diversity of mw satellites based on the gravothermal collapse of sidm haloes. this solution requires a velocity-dependent cross section that predicts a bimodal distribution of cuspy dense (collapsed) subhaloes consistent with the ultrafaint satellites, and cored lower density subhaloes consistent with the brighter satellites. | diverse dark matter density at sub-kiloparsec scales in milky way satellites: implications for the nature of dark matter |
in this work, we use an observational approach and dynamical system analysis to study the cosmological model recently proposed by saridakis (2020), which is based on the modification of the entropy-area black hole relation proposed by barrow (2020). the friedmann equations governing the dynamics of the universe under this entropy modification can be calculated through the gravity-thermodynamics conjecture. we investigate two models, one considering only a matter component and the other including matter and radiation, which have new terms compared to the standard model sourcing the late cosmic acceleration. a bayesian analysis is performed in which using five cosmological observations (observational hubble data, type ia supernovae, hii galaxies, strong lensing systems, and baryon acoustic oscillations) to constrain the free parameters of both models. from a joint analysis, we obtain constraints that are consistent with the standard cosmological paradigm within 2σ confidence level. in addition, a complementary dynamical system analysis using local and global variables is developed which allows obtaining a qualitative description of the cosmology. as expected, we found that the dynamical equations have a de sitter solution at late times. | barrow entropy cosmology: an observational approach with a hint of stability analysis |
axionlike particles (alps) coupled with electrons would be produced in a supernova (sn) via electron-proton bremsstrahlung and electron-positron fusion. we evaluate the alp emissivity from these processes by taking into account the alp mass and thermal effects on electrons in the strongly degenerate and relativistic sn plasma. using a state-of-the-art sn simulation, we evaluate the sn 1987a cooling bound on alps for masses in the range 1-200 mev, which excludes currently unprobed regions down to ga e∼2.5 ×10-10 at ma∼120 mev . | supernova bound on axionlike particles coupled with electrons |
the cosmographic approach, a taylor expansion of the hubble function, has been used as a model-independent method to investigate the evolution of the universe in the presence of cosmological data. apart from possible technical problems like the radius of convergence, there is an ongoing debate about the tensions that appear when one investigates some high-redshift cosmological data. in this work, we consider two common data sets, namely, type ia supernovae (pantheon sample) and the hubble data, to investigate advantages and disadvantages of the cosmographic approach. to do this, we obtain the evolution of cosmographic functions using the cosmographic method, as well as two other well-known model-independent approaches, namely, the gaussian process and the genetic algorithm. we also assume a λcdm model as the concordance model to compare the results of mentioned approaches. our results indicate that the results of cosmography compared with the other approaches are not exact enough. considering the hubble data, which are less certain, the results of q 0 and j 0 obtained in cosmography provide a tension at more than 3σ away from the best result of λcdm. assuming both of the data samples in different approaches, we show that the cosmographic approach, because it provides some biased results, is not the best approach for reconstruction of cosmographic functions, especially at higher redshifts. | cosmographic parameters in model-independent approaches |
we present three-dimensional simulations of core-collapse supernovae using the flash code that follow the progression of the explosion to the stellar surface, starting from neutrino radiation hydrodynamic simulations of the neutrino-driven phase performed with the chimera code. we consider a 9.6 m⊙ zero-metallicity progenitor starting from both 2d and 3d chimera models and a 10 m⊙ solar-metallicity progenitor starting from a 2d chimera model, all simulated until shock breakout in 3d while tracking 160 nuclear species. the relative velocity difference between the supernova shock and the metal-rich rayleigh-taylor (r-t) "bullets" determines how the metal-rich ejecta evolves as it propagates through the density profile of the progenitor and dictates the final morphology of the explosion. we find maximum 56ni velocities of ~1950 and ~1750 km s-1 at shock breakout from 2d and 3d 9.6 m⊙ chimera models, respectively, due to the bullets' ability to penetrate the he/h shell. when mapping from 2d, we find that the development of higher-velocity structures is suppressed when the 2d chimera model and 3d flash model meshes are aligned. the development of faster-growing spherical-bubble structures, as opposed to the slower-growing toroidal structure imposed by axisymmetry, allows for interaction of the bullets with the shock and seeds further r-t instabilities at the he/h interface. we see similar effects in the 10 m⊙ model, which achieves maximum 56ni velocities of ~2500 km s-1 at shock breakout. | three-dimensional core-collapse supernova simulations with 160 isotopic species evolved to shock breakout |
stellar candidates in the ursa minor (umi) dwarf galaxy have been found using a new bayesian algorithm applied to gaia edr3 data. five of these targets are located in the extreme outskirts of umi, from ~5 to 12 elliptical half-light radii (rh), where rh(umi) = 17.32 ± 0.11 arcmin, and have been observed with the high-resolution gemini remote access to cfht espadons spectrograph at the gemini north telescope. precise radial velocities (σrv < 2 km s-1) and metallicities ($\sigma _{\rm {{\rm [fe/h]}}}\ \lt\ 0.2$ dex) confirm their memberships of umi. detailed analysis of the brightest and outermost star (target 1, at ~12rh), yields precision chemical abundances for the α (mg, ca, and ti), odd-z (na, k, and sc), fe-peak (fe, ni, and cr), and neutron-capture (ba) elements. with data from the literature and apogee data release 17, we find the chemical patterns in umi are consistent with an outside-in star-formation history that includes yields from core-collapse supernovae, asymptotic giant branch stars, and type ia supernovae. evidence for a knee in the [α/fe] ratios near [fe/h] ~ -2.1 indicates a low star-formation efficiency similar to that in other dwarf galaxies. detailed analysis of the surface number density profile shows evidence that umi's outskirts have been populated by tidal effects, likely as a result of completing multiple orbits around the galaxy. | the extended 'stellar halo' of the ursa minor dwarf galaxy |
we analyze the simulation of dirac neutrino oscillations using quantum walks, both in a vacuum and in matter. we show that this simulation, in the continuum limit, reproduces a set of coupled dirac equations that describe neutrino flavor oscillations, and we make use of this to establish a connection with neutrino phenomenology, thus allowing one to fix the parameters of the simulation for a given neutrino experiment. we also analyze how matter effects for neutrino propagation can be simulated in the quantum walk. in this way, important features, such as the msw effect, can be incorporated. thus, the simulation of neutrino oscillations with the help of quantum walks might be useful to illustrate these effects in extreme conditions, such as the solar interior or supernovae. | quantum walks as simulators of neutrino oscillations in a vacuum and matter |
if the thermal evolution of the hot young neutron star in the supernova remnant hess j1731-347 is driven by neutrino emission, it provides a stringent constraint on the coupling of light (mass ≪10 kev ) axion-like particles to neutrons. using markov-chain monte carlo we find that for the values of axion-neutron coupling gan n 2>7.7 ×10-20 (90% c.l.) the axion cooling from the bremsstrahlung reaction n +n →n +n +a is too rapid to account for the high observed surface temperature. this implies that the pecci-quinn scale or axion decay constant fa>6.7 ×107gev for ksvz axions and fa>1.7 ×109gev for dfsz axions. the high temperature of this neutron star also allows us to tighten constraints on the size of the nucleon pairing gaps. | constraints on axion-like particles and nucleon pairing in dense matter from the hot neutron star in hess j1731-347 |
in this research, we construct kaniadakis holographic dark energy (khde) model within a nonflat universe by considering the friedmann-robertson-walker (frw) metric with open and closed spatial geometries. the kaniadakis entropy is indeed a one-parameter generalization of the classical boltzmann-gibbs-shannon entropy which emerges from a coherent and self-consistent relativistic statistical theory. we therefore investigate cosmic evolution by employing the density parameter of the dark energy (de), the equation-of-state (eos) parameter and the deceleration parameter (dp). the transition from decelerated to accelerated expanding phase for the khde universe is explained through dynamical behavior of dp. with the classification of matter- and de-dominated epochs, we find that the universe thermal history can be defined through the khde scenario, and moreover, a phantom regime is experienceable. the model parameters are constrained by applying the newest 30 data cases of h(z) measurements, over the redshift span 0.07 ≤ z ≤ 2.36, and the distance modulus measurement of the recent union 2.1 data set of type ia supernovae. the classical stability of khde model has also been addressed. | kaniadakis holographic dark energy in nonflat universe |
we examine the physical basis for algorithms to replace mixing-length theory (mlt) in stellar evolutionary computations. our 321d procedure is based on numerical solutions of the navier-stokes equations. these implicit large eddy simulations (iles) are three-dimensional (3d), time-dependent, and turbulent, including the kolmogorov cascade. we use the reynolds-averaged navier-stokes (rans) formulation to make concise the 3d simulation data, and use the 3d simulations to give closure for the rans equations. we further analyze this data set with a simple analytical model, which is non-local and time-dependent, and which contains both mlt and the lorenz convective roll as particular subsets of solutions. a characteristic length (the damping length) again emerges in the simulations; it is determined by an observed balance between (1) the large-scale driving, and (2) small-scale damping. the nature of mixing and convective boundaries is analyzed, including dynamic, thermal and compositional effects, and compared to a simple model. we find that (1) braking regions (boundary layers in which mixing occurs) automatically appear beyond the edges of convection as defined by the schwarzschild criterion, (2) dynamic (non-local) terms imply a non-zero turbulent kinetic energy flux (unlike mlt), (3) the effects of composition gradients on flow can be comparable to thermal effects, and (4) convective boundaries in neutrino-cooled stages differ in nature from those in photon-cooled stages (different péclet numbers). the algorithms are based upon iles solutions to the navier-stokes equations, so that, unlike mlt, they do not require any calibration to astronomical systems in order to predict stellar properties. implications for solar abundances, helioseismology, asteroseismology, nucleosynthesis yields, supernova progenitors and core collapse are indicated. | beyond mixing-length theory: a step toward 321d |
neutrinos emitted from a supernova may undergo flavor conversions almost immediately above the core, with possible consequences for supernova dynamics and nucleosynthesis. however, the precise conditions for such fast conversions can be difficult to compute and require knowledge of the full angular distribution of the flavor-dependent neutrino fluxes that is not available in typical supernova simulations. in this paper, we show that the overall flavor evolution is qualitatively similar to the growth of a so-called "zero mode" determined by the background matter and neutrino densities, which can be reliably predicted using only the second angular moments of the electron lepton number distribution, i.e., the difference in the angular distributions of the νe and ν¯ e fluxes. we propose that this zero mode, which neither requires computing the full green's function nor detailed knowledge of the angular distributions, may be useful for a preliminary diagnosis of possible fast flavor conversions in supernova simulations with modestly resolved angular distributions. | simple method of diagnosing fast flavor conversions of supernova neutrinos |
scalar fields aptly describe equation of state of dark energy. the scalar field models were initially proposed to circumvent the fine tuning problem of cosmological constant. however, the model parameters also need a fine tuning of their own and it is important to use different observations to determine these parameters. in this paper, we use a combination of low redshift data to constrain the low redshift evolution of canonical scalar field parameters. for this analysis, we use the supernova type ia observations, the baryon acoustic observations and the hubble parameter measurement data. we consider scalar field models of the thawing type of two different functional forms of potentials. the constraints on the model parameters are more stringent than those from earlier observations although these datasets do not rule out the models entirely. the parameters which let dark energy dynamics closely emulate that of a cosmological constant are preferred. the constraints on the parameters are suitable priors for further quintessence dark energy studies. | observational constraints on quintessence models of dark energy |
we propose a common envelope jets supernova (cejsn) scenario for the fast-rising blue optical transient at2018cow. in a cejsn, a neutron star (ns) spirals-in inside the extended envelope of a massive giant star and enters the core. the ns accretes mass from the core through an accretion disc and launches jets. these jets explode the core and the envelope. in the specific polar cejsn scenario that we propose here, the jets clear the polar regions of the giant star before the ns enters the core. the jets that the ns launches after it enters the core expand almost freely along the polar directions that contain a small amount of mass. this, we suggest, explains the fast rise to maximum and the fast ejecta observed at early times of the enigmatic transient at2018cow. the slower later time ejecta are the more massive equatorial outflow. we roughly estimate the accretion phase on to the ns during the explosion phase to last for a time of {≈ } 103 s, during which the average mass accretion rate is {≈ } 10^{-4} m_{\odot } s^{-1}. we outline the possible diversity of cejsne by listing five other scenarios in addition to the polar cejsn scenario. | diversity of common envelope jets supernovae and the fast transient at2018cow |
galactic winds from star-forming galaxies are crucial to the process of galaxy formation and evolution, regulating star formation, shaping the stellar mass function and the mass-metallicity relation, and enriching the intergalactic medium with metals. galactic winds associated with stellar feedback may be driven by overlapping supernova explosions, radiation pressure of starlight on dust grains, and cosmic rays. galactic winds are multiphase, the growing observations of emission and absorption of cold molecular, cool atomic, ionized warm and hot outflowing gas in a large number of galaxies have not been completely understood. in this review article, i summarize the possible mechanisms associated with stars to launch galactic winds, and review the multidimensional hydrodynamic, radiation hydrodynamic and magnetohydrodynamic simulations of winds based on various algorithms. i also briefly discuss the theoretical challenges and possible future research directions. | a review of the theory of galactic winds driven by stellar feedback |
during the first several days after explosion, type ia supernova light curves probe the outer layers of the exploding star, and therefore provide important clues for identifying their progenitors. we investigate how both the shallow 56ni distribution and the presence of circumstellar material shape these early light curves. this is performed using a series of numerical experiments with parameterized properties for systematic exploration. although not all of the considered models may be realized in nature (and indeed there are arguments why some of them should not occur), the spirit of this work is to provide a broader exploration of the diversity of possibilities. we find that shallower 56ni leads to steeper, bluer light curves. differences in the shape of the rise can introduce errors in estimating the explosion time, and thus impact efforts to infer upper limits on the progenitor or companion radius from a lack of observed shock cooling emission. circumstellar material can lead to significant luminosity during the first few days, but its presence can be difficult to identify depending on the degree of nickel mixing. in some cases, the hot emission of circumstellar material may even lead to a signature similar to an interaction with a companion, and thus in the future additional diagnostics should be gathered for properly assessing early light curves. | exploring the potential diversity of early type ia supernova light curves |
i review the physics of the diffuse supernova neutrino flux (or background, dsnb), in the context of future searches at the next generation of neutrino observatories. the theory of the dsnb is discussed in its fundamental elements, namely the cosmological rate of supernovae, neutrino production inside a core collapse supernova, redshift, and flavor oscillation effects. the current upper limits are also reviewed, and results are shown for the rates and energy distributions of the events expected at future liquid argon and liquid scintillator detectors of o(10) kt mass, and water cherenkov detectors up to a 0.5 mt mass. perspectives are given on the significance of future observations of the dsnb, both at the discovery and precision phases, for the investigation of the physics of supernovae and of the properties of the neutrino. | diffuse supernova neutrinos at underground laboratories |
it is difficult to establish the properties of massive stars that explode as supernovae. the electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. however, the unpredictable nature of supernova events hinders the detection of this brief initial phase. here we report the serendipitous discovery of a newly born, normal type iib supernova (sn 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. the very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. we develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. this result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion. | a surge of light at the birth of a supernova |
neutrino flavor transformations in core-collapse supernovae and binary neutron star mergers represent a complex and unsolved problem that is integral to our understanding of the dynamics and nucleosynthesis in these environments. the high number densities of neutrinos present in these environments can engender various collective effects in neutrino flavor transformations, driven either by neutrino-neutrino coherent scattering, or in some cases, through collisional (incoherent) interactions. an ensemble of neutrinos undergoing coherent scattering among themselves is an interacting quantum many-body system -- as such, there is a tantalising prospect of quantum entanglement developing between the neutrinos, which can leave imprints on their flavor evolution histories. here, we seek to summarize recent progress that has been made towards understanding this phenomenon. | many-body collective neutrino oscillations: recent developments |
young neutron stars (nss) born in core-collapse explosions are promising candidates for the central engines of fast radio bursts (frbs), since the first localized repeating burst frb 121102 occurs in a star-forming dwarf galaxy similar to the host galaxies of superluminous supernovae and long gamma-ray bursts. however, frb 180924 and frb 190523 are localized to massive galaxies with low rates of star formation, compared with the host of frb 121102. the offsets between the bursts and host centers are about 4 and 29 kpc for frb 180924 and frb 190523, respectively. these host properties are similar to those of short gamma-ray bursts (grbs), which are produced by binary neutron star (bns) or ns-black hole mergers. therefore, the nss powering frbs may be formed in bns mergers. in this paper, we study bns merger rates and merger times, and predict the most likely merger locations for different types of host galaxies using the population synthesis method. we find that the bns merger channel is consistent with the recently reported offsets of frb 180924 and frb 190523. the offset distribution of short grbs is well reproduced by population synthesis using a galaxy model similar to that of grb hosts. the event rate of frbs (including non-repeating and repeating), is larger than those of bns mergers and short grbs, and requires a large fraction of observed frbs emitting several bursts. using curvature radiation by bunches in ns magnetospheres, we also predict the observational properties of frbs from bns mergers, including the dispersion measure and rotation measure. at late times (t ≥ 1 yr), the contribution to dispersion measure and rotation measure from bns merger ejecta can be neglected. | fast radio bursts from activity of neutron stars newborn in bns mergers: offset, birth rate, and observational properties |
we present magnetohydrodynamic (mhd) simulations of the star-forming multiphase interstellar medium (ism) in stratified galactic patches with gas surface densities σgas = 10, 30, 50, and 100 $\mathrm{m_\odot \, pc^{-2}}$. the silcc project simulation framework accounts for non-equilibrium thermal and chemical processes in the warm and cold ism. the sink-based star formation and feedback model includes stellar winds, hydrogen-ionizing uv radiation, core-collapse supernovae, and cosmic ray (cr) injection and diffusion. the simulations follow the observed relation between σgas and the star formation rate surface density σsfr. crs qualitatively change the outflow phase structure. without crs, the outflows transition from a two-phase (warm and hot at 1 kpc) to a single-phase (hot at 2 kpc) structure. with crs, the outflow always has three phases (cold, warm, and hot), dominated in mass by the warm phase. the impact of crs on mass loading decreases for higher σgas and the mass loading factors of the cr-supported outflows are of order unity independent of σsfr. similar to observations, vertical velocity dispersions of the warm ionized medium (wim) and the cold neutral medium (cnm) correlate with the star formation rate as $\sigma _\mathrm{z} \propto \sigma _\mathrm{sfr}^a$, with a ~ 0.20. in the absence of stellar feedback, we find no correlation. the velocity dispersion of the wim is a factor ~2.2 higher than that of the cnm, in agreement with local observations. for $\sigma _\mathrm{sfr} \gtrsim 1.5 \times 10^{-2}\, \mathrm{m}_\odot \, \mathrm{yr}^{-1}\, \mathrm{kpc}^{-2}$ the wim motions become supersonic. | silcc - vii. gas kinematics and multiphase outflows of the simulated ism at high gas surface densities |
we present the detection of very-high-energy gamma-ray emission above 100 tev from hawc j2227+610 with the high-altitude water cherenov gamma-ray observatory (hawc) observatory. combining our observations with previously published results by the very energetic radiation imaging telescope array system (vertias), we interpret the gamma-ray emission from hawc j2227+610 as emission from protons with a lower limit in their cutoff energy of 800 tev. the most likely source of the protons is the associated supernova remnant g106.3+2.7, making it a good candidate for a galactic pevatron. however, a purely leptonic origin of the observed emission cannot be excluded at this time. | hawc j2227+610 and its association with g106.3+2.7, a new potential galactic pevatron |
solar neutrinos upscattering inside the earth can source unstable particles that subsequently decay inside large volume detectors (e.g., neutrino experiments). contrary to naive expectations, when the decay length is much shorter than the radius of the earth (rather than the length of the detector), the event rate is independent of the decay length. in this paper, we study a neutrino-dipole portal (transition dipole operator) and show that existing data from borexino and super-kamiokande probes previously untouched parameter space in the 0.5-20 mev regime, complementing recent cosmological and supernova bounds. we discuss similarities and differences with luminous dark matter and comment on future prospects for analogous signals stemming from atmospheric neutrinos. a companion paper explores an analogous mass-mixing portal. | luminous solar neutrinos. i. dipole portals |
dark energy could play a role at redshifts z ≫o (1 ). many quintessence models possess scaling or attractor solutions where the fraction of dark energy follows the dominant component in previous epochs of the universe's expansion, or phase transitions may happen close to the time of matter-radiation equality. a non-negligible early dark energy (ede) fraction around matter-radiation equality could contribute to alleviate the well-known h0 tension. in this work, we constrain the fraction of ede using two approaches: first, we use a fluid parametrization that mimics the plateaux of the dominant components in the past. an alternative tomographic approach constrains the ede density in binned redshift intervals. the latter allows us to reconstruct the evolution of ωde(z ) before and after the decoupling of the cosmic microwave background (cmb) photons. we have employed planck data 2018, the pantheon compilation of supernovae of type ia (snia), data on galaxy clustering, the prior on the absolute magnitude of snia by sh0es, and weak lensing data from kids +viking -450 and des-y1. when we use a minimal parametrization mimicking the background plateaux, ede has only a small impact on current cosmological tensions. we show how the constraints on the ede fraction weaken considerably when its sound speed is allowed to vary. by means of our binned analysis we put very tight constraints on the ede fraction around the cmb decoupling time, ≲0.4 % at 2 σ c.l. we confirm previous results that a significant ede fraction in the radiation-dominated epoch loosens the h0 tension, but tends to worsen the tension for σ8. a subsequent presence of ede in the matter-dominated era helps to alleviate this issue. when both the sh0es prior and weak lensing data are considered in the fitting analysis in combination with data from cmb, snia and baryon acoustic oscillations, the ede fractions are constrained to be ≲2.6 % in the radiation-dominated epoch and ≲1.5 % in the redshift range z ∈(100 ,1000 ) at 2 σ c.l. the two tensions remain with a statistical significance of ∼2 - 3 σ c.l. | early dark energy in the pre- and postrecombination epochs |
gamma-ray bursts are the most powerful explosions in the universe and are mainly placed at very large redshifts, up to z≃9. in this short review, we first discuss gamma-ray burst classification and morphological properties. we then report the likely relations between gamma-ray bursts and other astronomical objects, such as black holes, supernovae, neutron stars, etc., discussing in detail gamma-ray burst progenitors. we classify long and short gamma-ray bursts, working out their timescales, and introduce the standard fireball model. afterwards, we focus on direct applications of gamma-ray bursts to cosmology and underline under which conditions such sources would act as perfect standard candles if correlations between photometric and spectroscopic properties were not jeopardized by the circularity problem. in this respect, we underline how the shortage of low-z gamma-ray bursts prevents anchor gamma-ray bursts with primary distance indicators. moreover, we analyze in detail the most adopted gamma-ray burst correlations, highlighting their main differences. we therefore show calibration techniques, comparing such treatments with non-calibration scenarios. for completeness, we discuss the physical properties of the correlation scatters and systematics occurring during experimental computations. finally, we develop the most recent statistical methods, star formation rate, and high-redshift gamma-ray burst excess and show the most recent constraints obtained from experimental analyses. | a roadmap to gamma-ray bursts: new developments and applications to cosmology |
we study the impact of neutrino magnetic moments on astrophysical neutrinos, in particular supernova neutrinos and ultra-high energy neutrinos from extragalactic sources. we show that magnetic moment-induced conversion of left-handed neutrinos into unobservable right-handed singlet states can substantially change the flux and flavour composition of these neutrinos at earth. notably, neutrinos from a supernova's neutronisation burst, whose flux can be predicted with o(10%) accuracy, offer a discovery reach to neutrino magnetic moments $\sim \text{few} \times 10^{-13} \mu_b$, up to one order of magnitude below current limits. for high-energy neutrinos from distant sources, for which no robust flux prediction exists, we show how the flavour composition at earth can be used as a handle to establish the presence of non-negligible magnetic moments, potentially down to $\text{few} \times 10^{-17} \mu_b$ if the measurement can be performed on neutrinos from a single source. in both cases, the sensitivity strongly depends on the galactic resp. intergalactic magnetic field profiles along the line of sight. therefore, while a discovery is possible down to very small values of the magnetic moment, the absence of a discovery does not imply an equally strong limit. we also comment on the dependence of our results on the right-handed neutrino mass, paying special attention to the transition from coherent deflection by a classical magnetic field to incoherent scattering on individual scattering targets. finally, we show that a measurement of standard model dirac neutrino magnetic moments, of order $10^{-19} \mu_b$, could be possible under rather optimistic, but not completely outrageous, assumptions using flavour ratios of high-energy astrophysical neutrinos. | magnetic moments of astrophysical neutrinos |
supernovae ia are bright explosive events that can be used to estimate cosmological distances, allowing us to study the expansion of the universe. they are understood to result from a thermonuclear detonation in a white dwarf that formed from the exhausted core of a star more massive than the sun. however, the possible progenitor channels leading to an explosion are a long-standing debate, limiting the precision and accuracy of supernovae ia as distance indicators. here we present hd 265435, a binary system with an orbital period of less than a hundred minutes that consists of a white dwarf and a hot subdwarf, which is a stripped core-helium-burning star. the total mass of the system is 1.65 ± 0.25 solar masses, exceeding the chandrasekhar limit (the maximum mass of a stable white dwarf). the system will merge owing to gravitational wave emission in 70 million years, likely triggering a supernova ia event. we use this detection to place constraints on the contribution of hot subdwarf-white dwarf binaries to supernova ia progenitors. | a hot subdwarf-white dwarf super-chandrasekhar candidate supernova ia progenitor |
we apply bayesn, our new hierarchical bayesian model for the seds of type ia supernovae (sne ia), to analyse the griz light curves of 157 nearby sne ia (0.015 < z < 0.08) from the public foundation supernova survey data set. we train a new version of bayesn, continuous from 0.35 to 0.95 μm, which we use to model the properties of sne ia in the rest-frame z-band, study the properties of dust in their host galaxies, and construct a hubble diagram of sn ia distances determined from full griz light curves. our griz hubble diagram has a low total rms of 0.13 mag using bayesn, compared to 0.16 mag using salt2. additionally, we test the consistency of the dust law rv between low- and high-mass host galaxies by using our model to fit the full time- and wavelength-dependent seds of sne ia up to moderate reddening (peak apparent b - v ≲ 0.3). splitting the population at the median host mass, we find rv = 2.84 ± 0.31 in low-mass hosts, and rv = 2.58 ± 0.23 in high-mass hosts, both consistent with the global value of rv = 2.61 ± 0.21 that we estimate for the full sample. for all choices of mass split we consider, rv is consistent across the step within ≲ 1.2σ. modelling population distributions of dust laws in low- and high-mass hosts, we find that both subsamples are highly consistent with the full sample's population mean μ(rv) = 2.70 ± 0.25 with a 95 per cent upper bound on the population σ(rv) < 0.61. the rv population means are consistent within ≲ 1.2σ. we find that simultaneous fitting of host-mass-dependent dust properties within our hierarchical model does not account for the conventional mass step. | testing the consistency of dust laws in sn ia host galaxies: a bayesn examination of foundation dr1 |
formed in the aftermath of gravitational core-collapse supernova explosions, neutron stars are unique cosmic laboratories for probing the properties of matter under extreme conditions that cannot be reproduced in terrestrial laboratories. the interior of a neutron star, endowed with the highest magnetic fields known and with densities spanning about ten orders of magnitude from the surface to the centre, is predicted to exhibit various phases of dense strongly interacting matter, whose physics is reviewed in this chapter. the outer layers of a neutron star consist of a solid nuclear crust, permeated by a neutron ocean in its densest region, possibly on top of a nuclear "pasta" mantle. the properties of these layers and of the homogeneous isospin asymmetric nuclear matter beneath constituting the outer core may still be constrained by terrestrial experiments. the inner core of highly degenerate, strongly interacting matter poses a few puzzles and questions which are reviewed here together with perspectives for their resolution. consequences of the dense-matter phases for observables such as the neutron-star mass-radius relationship and the prospects to uncover their structure with modern observational programmes are touched upon. | phases of dense matter in compact stars |
directly comparing the 6 expansion rate measured by type ia supernovae data and the lower bound on the expansion rate set by the strong energy conditions or the null hypothesis that there never exists cosmic acceleration, we see 3σ direct evidence of cosmic acceleration and the rh=ct model is strongly excluded by the type ia supernovae data. we also use gaussian process method to reconstruct the expansion rate and the deceleration parameter from the 31 cosmic chronometers data and the 6 data points on the expansion rate measured from type ia supernoave data, the direct evidence of cosmic acceleration is more than 3σ and we find that the transition redshift zt=0.60-0.12+0.21 at which the expansion of the universe underwent the transition from acceleration to deceleration. the hubble constant inferred from the cosmic chronometers data with the gaussian process method is h0=67.46±4.75 km/s/mpc. to understand the properties of cosmic acceleration and dark energy, we fit two different two-parameter models to the observational data, and we find that the constraints on the model parameters from either the full distance modulus data by the pantheon compilation or the compressed expansion rate data are very similar, and the derived hubble constants are consistent with the planck 2018 result. our results confirm that the 6 compressed expansion rate data can replace the full 1048 distance modulus data from the pantheon compilation. we derive the transition redshift zt=0.61-0.16+0.24 by fitting a simple q(z) model to the combination of cosmic chronometers data and the pantheon compilation, the result is consistent with that obtained from the reconstruction with gaussian process. by fitting the observational data by the sslcpl model which approximates the dynamics of general thawing scalar fields over a large redshift range, we obtain that h0=66.8± 1.4, ωphi 0=0.69± 0.01 and w0=-1.03± 0.07. the result shows that λcdm model is consistent with the observational data. | the evidence of cosmic acceleration and observational constraints |
we present a high-resolution view of bubbles within the phantom galaxy (ngc 628), a nearby (~10 mpc), star-forming (~2 m ⊙ yr-1), face-on (i ~ 9°) grand-design spiral galaxy. with new data obtained as part of the physics at high angular resolution in nearby galaxies (phangs)-jwst treasury program, we perform a detailed case study of two regions of interest, one of which contains the largest and most prominent bubble in the galaxy (the phantom void, over 1 kpc in diameter), and the other being a smaller region that may be the precursor to such a large bubble (the precursor phantom void). when comparing to matched-resolution hα observations from the hubble space telescope, we see that the ionized gas is brightest in the shells of both bubbles, and is coincident with the youngest (~1 myr) and most massive (~105 m ⊙) stellar associations. we also find an older generation (~20 myr) of stellar associations is present within the bubble of the phantom void. from our kinematic analysis of the h i, h2 (co), and h ii gas across the phantom void, we infer a high expansion speed of around 15 to 50 km s-1. the large size and high expansion speed of the phantom void suggest that the driving mechanism is sustained stellar feedback due to multiple mechanisms, where early feedback first cleared a bubble (as we observe now in the precursor phantom void), and since then supernovae have been exploding within the cavity and have accelerated the shell. finally, comparison to simulations shows a striking resemblance to our jwst observations, and suggests that such large-scale, stellar-feedback-driven bubbles should be common within other galaxies. | phangs-jwst first results: multiwavelength view of feedback-driven bubbles (the phantom voids) across ngc 628 |
astrophysical collisionless shocks are common in the universe, occurring in supernova remnants, gamma ray bursts, and protostellar jets. they appear in colliding plasma flows when the mean free path for ion-ion collisions is much larger than the system size. it is believed that such shocks could be mediated via the electromagnetic weibel instability in astrophysical environments without pre-existing magnetic fields. here, we present laboratory experiments using high-power lasers and investigate the dynamics of high-mach-number collisionless shock formation in two interpenetrating plasma streams. our recent proton-probe experiments on omega show the characteristic filamentary structures of the weibel instability that are electromagnetic in nature with an inferred magnetization level as high as ∼1% [c. m. huntington et al., "observation of magnetic field generation via the weibel instability in interpenetrating plasma flows," nat. phys. 11, 173-176 (2015)]. these results imply that electromagnetic instabilities are significant in the interaction of astrophysical conditions. | collisionless shock experiments with lasers and observation of weibel instabilities |
we study mass-loss from the outer lagrange point (l2) in binary stellar mergers and their luminous transients by means of radiative hydrodynamical simulations. previously, we showed that for binary mass ratios 0.06 ≲ q ≲ 0.8, synchronous l2 mass-loss results in a radiatively inefficient, dust-forming unbound equatorial outflow. a similar outflow exists irrespective of q if the ratio of the sound speed to the orbital speed at the injection point is sufficiently large, ɛ ≡ ct/vorb ≳ 0.15. by contrast, for cold l2 mass-loss (ɛ ≲ 0.15) from binaries with q ≲ 0.06 or q ≳ 0.8, the equatorial outflow instead remains marginally bound and falls back to the binary over tens to hundreds of binary orbits, where it experiences additional tidal torquing and shocking. as the bound gas becomes virialized with the binary, the luminosity of the system increases slowly at approximately constant photosphere radius, causing the temperature to rise. subsequent evolution depends on the efficiency of radiative cooling. if the bound atmosphere is able to cool efficiently, as quantified by radiative diffusion time being shorter than the advection time (tdiff/tadv ≪ 1), then the virialized gas collapses to an excretion disc, while for tdiff/tadv ≳ 1 an isotropic wind is formed. between these two extremes, an inflated envelope transports the heat generated near the binary to the surface by meridional flows. in all cases, the radiated luminosity reaches a fraction ∼10-2 to 10-1 of dot{m}v_orb^2/2, where dot{m} is the mass outflow rate. we discuss the implications of our results for transients in the luminosity gap between classical novae and supernovae, such as v1309 sco and v838 mon. | binary stellar mergers with marginally bound ejecta: excretion discs, inflated envelopes, outflows, and their luminous transients |
we present results of 2d axisymmetric core-collapse supernova simulations, employing the fornax code, of nine progenitor models spanning 12 to 25 m⊙. four of the models explode with inelastic scattering off electrons and neutrons as well as the many-body correction to neutrino-nucleon scattering opacities. we show that these four models feature sharp si-o interfaces in their density profiles, and that the corresponding dip in density reduces the accretion rate around the stalled shock and prompts explosion. the non-exploding models lack such a steep feature, highlighting the si-o interface as one key to explosion. furthermore, we show that all of the non-exploding models can be nudged to explosion with modest changes to macrophysical inputs, including moderate rotation and perturbations to infall velocities, as well as to microphysical inputs, including reasonable changes to neutrino-nucleon interaction rates, suggesting that all the models are perhaps close to criticality. exploding models have energies of a few × 1050 erg at the end of our simulation, and are rising, emphasizing the need to continue these simulations over larger grids and for longer times to reproduce the energies seen in nature. morphology of the explosion contributes to the explosion energy, with more isotropic ejecta producing larger explosion energies. we do not find evidence for the lepton-number emission self-sustained asymmetry. finally, we look at proto-neutron star (pns) properties and explore the role of dimension in our simulations. we find that convection in the pns produces larger pns radii as well as greater `νμ' luminosities in 2d compared to 1d. | revival of the fittest: exploding core-collapse supernovae from 12 to 25 m⊙ |
recent results from the pierre auger collaboration have shown that the composition of ultrahigh-energy cosmic rays (uhecrs) becomes gradually heavier with increasing energy. although gamma-ray bursts (grbs) have been promising sources of uhecrs, it is still unclear whether they can account for the auger results because of their unknown nuclear composition of ejected uhecrs. in this work, we revisit the possibility that low-luminosity grbs (ll grbs) act as the sources of uhecr nuclei and give new predictions based on the intrajet nuclear composition models considering progenitor dependencies. we find that the nuclear component in the jet can be divided into two groups according to the mass fraction of silicon nuclei, si-free and si-rich. motivated by the connection between ll grbs and transrelativistic supernovae, we also consider the hypernova ejecta composition. then, we discuss the survivability of uhecr nuclei in the jet base and internal shocks of the jets, and show that it is easier for nuclei to survive for typical ll grbs. finally, we numerically propagate uhecr nuclei ejected from ll grbs with different composition models and compare the resulting spectra and composition to auger data. our results show that both the si-rich progenitor and hypernova ejecta models match the auger data well, while the si-free progenitor models have more difficulty in fitting the spectrum. we argue that our model is consistent with the newly reported cross-correlation between the uhecrs and starburst galaxies, since both ll grbs and hypernovae are expected to be tracers of the star-formation activity. ll grbs have also been suggested as the dominant origin of icecube neutrinos in the pev range, and the ll grb origin of uhecrs can be critically tested by near-future multimessenger observations. | low-luminosity gamma-ray bursts as the sources of ultrahigh-energy cosmic ray nuclei |
self induced neutrino flavor conversions in the dense regions of stellar core collapse are almost exclusively studied in the standard two flavor scenario. linear stability analysis has been successfully used to understand these flavor conversions. this is the first linearized study of three flavor fast instabilities. the 'fast' conversions are fascinating distinctions of the dense neutrino systems. in the fast modes the collective oscillation dynamics are independent of the neutrino mass, growing at the scale of the large neutrino-neutrino interaction strength (105 km-1) of the dense core. this is extremely fast, in comparison to the usual 'slow' collective modes driven by much smaller vacuum oscillation frequencies (100 km-1). the three flavor analysis shows distinctive characteristics for both the slow and the fast conversions. the slow oscillation results are in qualitative agreement with the existing nonlinear three flavor studies. for the fast modes, addition of the third flavor opens up possibilities of influencing the growth rates of flavor instabilities when compared to a two flavor scenario. | three flavor neutrino conversions in supernovae: slow & fast instabilities |
realizing refsdal’s original idea from 1964, we present estimates of the hubble constant that are complementary to, and potentially competitive with, those of other cosmological probes. we use the observed positions of 89 multiple images, with extensive spectroscopic information, from 28 background sources and the measured time delays between the images s1-s4 and sx of supernova “refsdal” (z = 1.489), which were obtained thanks to hubble space telescope deep imaging and multi unit spectroscopic explorer data. we extend the strong-lensing modeling of the hubble frontier fields galaxy cluster macs j1149.5+2223 (z = 0.542), published by grillo et al. (2016), and explore different λcdm models. taking advantage of the lensing information associated to the presence of very close pairs of multiple images at various redshifts, and to the extended surface brightness distribution of the sn refsdal host, we can reconstruct the total mass-density profile of the cluster very precisely. the combined dependence of the multiple-image positions and time delays on the cosmological parameters allows us to infer the values of h 0 and ωm with relative (1σ) statistical errors of, respectively, 6% (7%) and 31% (26%) in flat (general) cosmological models, assuming a conservative 3% uncertainty on the final time delay of image sx and, remarkably, no priors from other cosmological experiments. our best estimate of h 0, based on the model described in this work, will be presented when the final time-delay measurement becomes available. our results show that it is possible to utilize time delays in lens galaxy clusters as an important alternative tool for measuring the expansion rate and the geometry of the universe. | measuring the value of the hubble constant “à la refsdal” |
we investigate r-process nucleosynthesis in three-dimensional general relativistic magnetohydrodynamic simulations of jet-driven supernovae resulting from rapidly rotating, strongly magnetized core-collapse. we explore the effect of misaligning the pre-collapse magnetic field with respect to the rotation axis by performing four simulations: one aligned model and models with 15°, 30°, and 45° misalignments. the simulations we present employ a microphysical finite-temperature equation of state and a leakage scheme that captures the overall energetics and lepton number exchange due to post-bounce neutrino emission and absorption. we track the thermodynamic properties of the ejected material with lagrangian tracer particles and analyse its composition with the nuclear reaction network skynet. by using different neutrino luminosities in post-processing the tracer data with skynet, we constrain the impact of uncertainties in neutrino luminosities. we find that, for the aligned model considered here, the use of an approximate leakage scheme results in neutrino luminosity uncertainties corresponding to a factor of 100-1000 uncertainty in the abundance of third peak r-process elements. our results show that for misalignments of 30° or less, r-process elements are robustly produced as long as neutrino luminosities are reasonably low (≲ 5 × 1052 erg s-1). for a more extreme misalignment of 45°, we find the production of r-process elements beyond the second peak significantly reduced. we conclude that robust r-process nucleosynthesis in magnetorotational supernovae requires a progenitor stellar core with a large poloidal magnetic field component that is at least moderately (within ∼30°) aligned with the rotation axis. | r-process nucleosynthesis from three-dimensional jet-driven core-collapse supernovae with magnetic misalignments |
recent observations of type ia supernovae (sne ia) have shown diversified properties of the explosion strength, light curves, and chemical composition. to investigate possible origins of such diversities in sne ia, we have presented multidimensional hydrodynamical studies of explosions and associated nucleosynthesis in near-chandrasekhar-mass carbon-oxygen (co) white dwarfs (wds) for a wide range of parameters. in the present paper, we extend our wide parameter survey of models to the explosions of sub-chandrasekhar-mass co wds. we take the double-detonation model for the explosion mechanism. the model parameters of the survey include a metallicity of z = 0-5 z ⊙, a co wd mass of m = 0.90-1.20 m ⊙, and a he envelope mass of m he = 0.05-0.20 m ⊙. we also study how the initial he detonation configuration, such as spherical, bubble, and ring shapes, triggers the c detonation. for these parameters, we derive the minimum he envelope mass necessary to trigger the c detonation. we then examine how the explosion dynamics and associated nucleosynthesis depend on these parameters, and we compare our results with the previous representative models. we compare our nucleosynthesis yields with the unusual abundance patterns of fe-peak elements and isotopes observed in sne ia sn 2011fe, sn 2012cg, and sn 2014j, as well as sn ia remnant 3c 397, to provide constraints on their progenitors and environments. we provide the nucleosynthesis yields table of the sub-chandrasekhar-mass explosions, to discuss their roles in the galactic chemical evolution and archaeology. | explosive nucleosynthesis in sub-chandrasekhar-mass white dwarf models for type ia supernovae: dependence on model parameters |
the next galactic core-collapse supernova (ccsn) has already exploded, and its electromagnetic (em) waves, neutrinos, and gravitational waves (gws) may arrive at any moment. we present an extensive study on the potential sensitivity of prospective detection scenarios for gws from ccsne within 5 mpc, using realistic noise at the predicted sensitivity of the advanced ligo and advanced virgo detectors for 2015, 2017, and 2019. we quantify the detectability of gws from ccsne within the milky way and large magellanic cloud, for which there will be an observed neutrino burst. we also consider extreme gw emission scenarios for more distant ccsne with an associated em signature. we find that a three-detector network at design sensitivity will be able to detect neutrino-driven ccsn explosions out to ∼5.5 kpc , while rapidly rotating core collapse will be detectable out to the large magellanic cloud at 50 kpc. of the phenomenological models for extreme gw emission scenarios considered in this study, such as long-lived bar-mode instabilities and disk fragmentation instabilities, all models considered will be detectable out to m31 at 0.77 mpc, while the most extreme models will be detectable out to m82 at 3.52 mpc and beyond. | observing gravitational waves from core-collapse supernovae in the advanced detector era |
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