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gas blown away from galactic disks by supernova (sn) feedback plays a key role in galaxy evolution. we investigate outflows utilizing the solar neighborhood model of our high-resolution, local galactic disk simulation suite, tigress. in our numerical implementation, star formation and sn feedback are self-consistently treated and well resolved in the multiphase, turbulent, magnetized interstellar medium. bursts of star formation produce spatially and temporally correlated sne that drive strong outflows, consisting of hot (t> 5× 105 k) winds and warm (5050 k< t< 2× 104 k) fountains. the hot gas at distance d> 1 kpc from the midplane has mass and energy fluxes nearly constant with d. the hot flow escapes our local cartesian box barely affected by gravity, and is expected to accelerate up to terminal velocity of vwind∼ 350--500 km s-1. the mean mass and energy loading factors of the hot wind are 0.1 and 0.02, respectively. for warm gas, the mean outward mass flux through d=1 kpc is comparable to the mean star formation rate, but only a small fraction of this gas is at velocity > 50 km s-1. thus, the warm outflows eventually fall back as inflows. the warm fountain flows are created by expanding hot superbubbles at d< 1 kpc; at larger d neither ram pressure acceleration nor cooling transfers significant momentum or energy flux from the hot wind to the warm outflow. the velocity distribution at launching near d∼ 1 kpc is a better representation of warm outflows than a single mass loading factor, potentially enabling development of subgrid models for warm galactic winds in arbitrary large-scale galactic potentials. | numerical simulations of multiphase winds and fountains from star-forming galactic disks. i. solar neighborhood tigress model |
we show that the h0 tension can be resolved by making recombination occur earlier, keeping the fit to cosmic microwave background (cmb) data almost intact. we provide a suite of general necessary conditions to give a good fit to cmb data while realizing a high value of h0 suggested by local measurements. as a concrete example for a successful scenario with early recombination, we demonstrate that a model with a time-varying me can indeed satisfy all of the conditions. we further show that such a model can also be well fitted to low-z distance measurements of baryon acoustic oscillations (bao) and type ia supernovae (sneia) with a simple extension of the model. a time-varying me in the framework of ωkλ cdm is found to be a sufficient and excellent example of a solution to the h0 tension, yielding h0=72.3-2.8+2.7 km /sec /mpc from the combination of cmb, bao, and sneia data even without incorporating any direct local h0 measurements. employing the bayesian posterior predictive distribution, we find that this model can reduce the h0 tension in the reference λ cdm model from 4.8 σ down to 2.2 σ . apart from the h0 tension, this model is also favored from the viewpoint of the cmb lensing anomaly. | early recombination as a solution to the h0 tension |
we present a novel framework for the equation of state of dense and hot quantum chromodynamics (qcd), which focuses on the region of the phase diagram relevant for neutron star mergers and core-collapse supernovae. the model combines predictions from the gauge/gravity duality with input from lattice field theory, qcd perturbation theory, chiral effective theory, and statistical modeling. it is therefore, by construction, in good agreement with theoretical constraints both at low and high densities and temperatures. the main ingredients of our setup are the nonperturbative v-qcd model based on the gauge/gravity duality, a van der waals model for nucleon liquid, and the dd2 version of the hempel-schaffner-bielich statistical model of nuclear matter. by consistently combining these models, we also obtain a description for the nuclear to quark matter phase transition and its critical end point. the parameter dependence of the model is represented by three (soft, intermediate, and stiff) variants of the equation of state, all of which agree with observational constraints from neutron stars and their mergers. we discuss resulting constraints for the equation of state, predictions for neutron stars, and the location of the critical point. | dense and hot qcd at strong coupling |
we present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (slsne) discovered by the palomar transient factory prior to 2013 and derive measurements of their luminosities, star formation rates, stellar masses, and gas-phase metallicities. we find that type i (hydrogen-poor) slsne (slsne i) are found almost exclusively in low-mass ({m}* \lt 2× {10}9 {m}⊙ ) and metal-poor (12 + log10[o/h] \lt 8.4) galaxies. we compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of slsne i as a fraction of all sne is heavily suppressed in galaxies with metallicities ≳ 0.5 {z}⊙ . extremely low metallicities are not required and indeed provide no further increase in the relative slsn rate. several slsn i hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star formation histories. type ii (hydrogen-rich) slsne (slsne ii) are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. two hosts exhibit unusual properties: ptf 10uhf is an slsn i in a massive, luminous infrared galaxy at redshift z = 0.29, while ptf 10tpz is an slsn ii located in the nucleus of an early-type host at z = 0.04. | host-galaxy properties of 32 low-redshift superluminous supernovae from the palomar transient factory |
we present a new determination of the concentration-mass (c-m) relation for galaxy clusters based on our comprehensive lensing analysis of 19 x-ray selected galaxy clusters from the cluster lensing and supernova survey with hubble (clash). our sample spans a redshift range between 0.19 and 0.89. we combine weak-lensing constraints from the hubble space telescope (hst) and from ground-based wide-field data with strong lensing constraints from hst. the results are reconstructions of the surface-mass density for all clash clusters on multi-scale grids. our derivation of navarro-frenk-white parameters yields virial masses between 0.53× {{10}15} {{m}⊙ }/h and 1.76× {{10}15} {{m}⊙ }/h and the halo concentrations are distributed around {{c}200c}∼ 3.7 with a 1σ significant negative slope with cluster mass. we find an excellent 4% agreement in the median ratio of our measured concentrations for each cluster and the respective expectation from numerical simulations after accounting for the clash selection function based on x-ray morphology. the simulations are analyzed in two dimensions to account for possible biases in the lensing reconstructions due to projection effects. the theoretical c-m relation from our x-ray selected set of simulated clusters and the c-m relation derived directly from the clash data agree at the 90% confidence level. | clash: the concentration-mass relation of galaxy clusters |
we explore the impact of small-scale flavor conversions of neutrinos, the so-called fast flavor conversions (ffcs), on the dynamical evolution and neutrino emission of core-collapse supernovae (ccsne). in order to do that, we implement ffcs in the spherically symmetric (1d) ccsn simulations of a 20 m⊙ progenitor model parametrically, assuming that ffcs happen at densities lower than a systematically varied threshold value and lead to an immediate flavor equilibrium consistent with lepton number conservation. we find that besides hardening the νe and ν¯e spectra, which helps the expansion of the shock by enhanced postshock heating, ffcs can cause significant, nontrivial modifications of the energy transport in the sn environment via increasing the νμ ,τ luminosities. in our nonexploding models this results in extra cooling of the layers around the neutrinospheres, which triggers a faster contraction of the protoneutron star and hence, in our 1d models, hampers the ccsn explosion. although our study is limited by the 1d nature of our simulations, it provides valuable insights into how neutrino flavor conversions in the deepest ccsn regions can impact the neutrino release and the corresponding response of the stellar medium. | fast neutrino flavor conversion in core-collapse supernovae: a parametric study in 1d models |
fast-pairwise collective neutrino oscillation represents a key uncertainty in the theory of core-collapse supernova (ccsn). despite the potentially significant impact on ccsn dynamics, it is usually neglected in numerical models of ccsn because of the formidable technical difficulties of self-consistently incorporating this physics. in this paper, we investigate the prospects for the occurrence of fast flavor conversion by diagnosing electron neutrino lepton number (eln) crossing in more than a dozen state-of-the-art three-dimensional ccsn models. eln crossings provide a necessary condition for triggering flavor conversion. although only zeroth and first angular moments are available from the simulations, our new method enables us to look into the angular distributions of neutrinos in momentum space and provide accurate insight into eln crossings. our analysis suggests that fast flavor conversion generally occurs in the postshock region of ccsne, and that explosive models provide more favorable conditions for the flavor conversion than failed ccsne. we also find that there are both common and progenitor-dependent characteristics. classifying eln crossings into two types, we analyze the generation mechanism of each case by scrutinizing the neutrino radiation field and matter interactions. we find key ingredients of ccsn dynamics driving the eln crossings: proto-neutron star convection, asymmetric neutrino emission, neutrino absorptions, and scatterings. this study suggests that we need to accommodate fast flavor conversions in realistic ccsn models. | where, when, and why: occurrence of fast-pairwise collective neutrino oscillation in three-dimensional core-collapse supernova models |
the all-sky automated survey for supernovae (asas-sn) provides long-baseline (∼4 yr) light curves for sources brighter than v ≲ 17 mag across the whole sky. the transiting exoplanet survey satellite (tess) has started to produce high-quality light curves with a baseline of at least 27 d, eventually for most of the sky. the combination of asas-sn and tess light curves probes both long- and short-term variability in great detail, especially towards the tess continuous viewing zones (cvz) at the ecliptic poles. we have produced ∼1.3 million v-band light curves covering a total of {∼ }1000 deg^2 towards the southern tess cvz and have systematically searched these sources for variability. we have identified ∼11 700 variables, including ∼7 000 new discoveries. the light curves and characteristics of the variables are all available through the asas-sn variable stars data base (https://asas-sn.osu.edu/variables). we also introduce an online resource to obtain pre-computed asas-sn v-band light curves (https://asas-sn.osu.edu/photometry) starting with the light curves of the ∼1.3 million sources studied in this work. this effort will be extended to provide asas-sn light curves for ∼50 million sources over the entire sky. | the asas-sn catalogue of variable stars iii: variables in the southern tess continuous viewing zone |
our current understanding of the stellar initial mass function and massive star evolution suggests that young globular clusters (gcs) may have formed hundreds to thousands of stellar-mass black holes (bhs), the remnants of stars with initial masses from ~20-100 m ⊙. birth kicks from supernova explosions may eject some bhs from their birth clusters, but most should be retained. using a monte carlo method we investigate the long-term dynamical evolution of gcs containing large numbers of stellar bhs. we describe numerical results for 42 models, covering a broad range of realistic initial conditions, including up to 1.6 × 106 stars. in almost all models we find that significant numbers of bhs (up to ~103) are retained all the way to the present. this is in contrast to previous theoretical expectations that most bhs should be ejected dynamically within a few gigayears the main reason for this difference is that core collapse driven by bhs (through the spitzer "mass segregation instability") is easily reverted through three-body processes, and involves only a small number of the most massive bhs, while lower-mass bhs remain well-mixed with ordinary stars far from the central cusp. thus the rapid segregation of stellar bhs does not lead to a long-term physical separation of most bhs into a dynamically decoupled inner core, as often assumed previously. combined with the recent detections of several bh x-ray binary candidates in galactic gcs, our results suggest that stellar bhs could still be present in large numbers in many gcs today, and that they may play a significant role in shaping the long-term dynamical evolution and the present-day dynamical structure of many clusters. | the dynamical evolution of stellar black holes in globular clusters |
context. as a result of their formation via massive single and binary stellar evolution, the masses of stellar-remnant black holes (bh) are subjects of great interest in this era of gravitational-wave detection from binary black hole (bbh) and binary neutron star merger events.aims: in this work, we present new developments in the stellar-remnant formation and related schemes of the current n-body evolution program nbody7. we demonstrate that the newly implemented stellar-wind and remnant-formation schemes in the stellar-evolutionary sector or bse of the nbody7 code, such as the "rapid" and the "delayed" supernova (sn) schemes along with an implementation of pulsational-pair-instability and pair-instability supernova (ppsn/psn), now produce neutron star (ns) and bh masses that agree nearly perfectly, over large ranges of zero-age-main-sequence (zams) mass and metallicity, with those from the widely recognised startrack population-synthesis program. we also demonstrate the new, recipe-based implementations of various widely debated mechanisms of natal kicks on nss and bhs, such as "convection-asymmetry-driven", "collapse-asymmetry-driven", and "neutrino-emission-driven" kicks, in addition to a fully consistent implementation of the standard, fallback-dependent, momentum-conserving natal kick.methods: all the above newly implemented schemes are also shared with the standalone versions of sse and bse. all these demonstrations are performed with both the updated standalone bse and the updated nbody7/bse.results: when convolved with stellar and primordial-binary populations as observed in young massive clusters, such remnant-formation and natal-kick mechanisms crucially determine the accumulated number, mass, and mass distribution of the bhs retained in young massive, open, and globular clusters (gcs); these bhs would eventually become available for long-term dynamical processing.conclusions: among other conclusions, we find that although the newer, delayed sn remnant formation model gives birth to the largest number (mass) of bhs, the older remnant-formation schemes cause the largest number (mass) of bhs to survive in clusters, when incorporating sn material fallback onto the bhs. the sn material fallback also causes the convection-asymmetry-driven sn kick to effectively retain similar numbers and masses of bhs in clusters as for the standard, momentum-conserving kick. the collapse-asymmetry-driven sn kick would cause nearly all bhs to be retained in clusters irrespective of their mass, remnant-formation model, and metallicity, whereas the inference of a large population of bhs in gcs would potentially rule out the neutrino-driven sn kick mechanism. pre-sn mergers of massive primordial binaries would potentially cause bh masses to deviate from the theoretical, single-star zams to mass-remnant mass relation unless a substantial of the total merging stellar mass of up to ≈40% is lost during a merger process. in particular, such mergers, at low metallicities, have the potential to produce low-spinning bhs within the psn mass gap that can be retained in a stellar cluster and be available for subsequent dynamical interactions. as recent studies indicate, the new remnant-formation modelling reassures us that young massive and open clusters would potentially contribute to the dynamical bbh merger detection rate to a similar extent as their more massive gc counterparts. | bse versus startrack: implementations of new wind, remnant-formation, and natal-kick schemes in nbody7 and their astrophysical consequences |
we construct modified cosmological scenarios through the application of the first law of thermodynamics on the universe horizon, but using the generalized, nonextensive tsallis entropy instead of the usual bekenstein-hawking one. we result to modified cosmological equations that possess the usual ones as a particular limit, but which in the general case contain extra terms that appear for the first time, that constitute an effective dark energy sector quantified by the nonextensive parameter δ . when the matter sector is dust, we extract analytical expressions for the dark energy density and equation-of-state parameters, and we extend these solutions to the case where radiation is present too. we show that the universe exhibits the usual thermal history, with the sequence of matter and dark-energy eras, and according to the value of δ the dark-energy equation-of-state parameter can be quintessence-like, phantom-like, or experience the phantom-divide crossing during the evolution. even in the case where the explicit cosmological constant is absent, the scenario at hand can very efficiently mimic λ cdm cosmology, and is in excellent agreement with supernovae type ia observational data. | modified cosmology through nonextensive horizon thermodynamics |
in this paper, we present the results of our three-dimensional, multigroup, multineutrino-species radiation/hydrodynamic simulation using the state-of-the-art code fornax of the terminal dynamics of the core of a non-rotating 16 m⊙ stellar progenitor. the calculation incorporates redistribution by inelastic scattering, a correction for the effect of many-body interactions on the neutrino-nucleon scattering rates, approximate general relativity (including the effects of gravitational redshifts), velocity-dependent frequency advection, and an implementation of initial perturbations in the progenitor core. the model explodes within ∼100 ms of bounce (near when the silicon-oxygen interface is accreted through the temporarily stalled shock) and by the end of the simulation (here, ∼677 ms after bounce) is accumulating explosion energy at a rate of ∼2.5 × 1050 erg s-1. the supernova explodes with an asymmetrical multiplume structure, with one hemisphere predominating. the gravitational mass of the residual proto-neutron star at ∼677 ms is ∼1.42 m⊙. even at the end of the simulation, explosion in most of the solid angle is accompanied by some accretion in an annular region at the wasp-like waist of the debris field. the ejecta electron fraction (ye) is distributed between ∼0.48 and ∼0.56, with most of the ejecta mass proton-rich. this may have implications for supernova nucleosynthesis, and could have a bearing on the p- and νp-processes and on the site of the first peak of the r-process. the ejecta spatial distributions of both ye and mass density are predominantly in wide-angle plumes and large-scale structures, but are nevertheless quite patchy. | a successful 3d core-collapse supernova explosion model |
the post-helium-burning evolution of stars from 7 {m}⊙to 11 {m}⊙is complicated by the lingering effects of degeneracy and off-center ignition. here, stars in this mass range are studied using a standard set of stellar physics. two important aspects of the study are the direct coupling of a reaction network of roughly 220 nuclei to the structure calculation at all stages and the use of a subgrid model to describe the convective bounded flame that develops during neon and oxygen burning. below 9.0 {m}⊙degenerate oxygen-neon cores form that may become either white dwarfs or electron-capture supernovae. above 10.3 {m}⊙the evolution proceeds “normally” to iron-core collapse, without composition inversions or degenerate flashes. emphasis here is upon the stars in between, which typically ignite oxygen burning off-center. after oxygen burns in a convectively bounded flame, silicon burning ignites in a degenerate flash that commences closer to the stellar center and with increasing violence for stars of larger mass. in some cases the silicon flash is so violent that it could lead to the early ejection of the hydrogen envelope. this might have interesting observable consequences. for example, the death of a 10.0 {m}⊙star could produce two supernova-like displays, a faint low-energy event due to the silicon flash, and an unusually bright supernova many months later as the low-energy ejecta from core collapse collides with the previously ejected envelope. the potential relation to the crab supernova is discussed. | the remarkable deaths of 9-11 solar mass stars |
the preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay—these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. the deep underground neutrino experiment (dune) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. the dune far detector technical design report (tdr) describes the dune physics program and the technical designs of the single- and dual-phase dune liquid argon tpc far detector modules. volume iii of this tdr describes how the activities required to design, construct, fabricate, install, and commission the dune far detector modules are organized and managed. this volume details the organizational structures that will carry out and/or oversee the planned far detector activities safely, successfully, on time, and on budget. it presents overviews of the facilities, supporting infrastructure, and detectors for context, and it outlines the project-related functions and methodologies used by the dune technical coordination organization, focusing on the areas of integration engineering, technical reviews, quality assurance and control, and safety oversight. because of its more advanced stage of development, functional examples presented in this volume focus primarily on the single-phase (sp) detector module. | volume iii. dune far detector technical coordination |
we introduce tigress, a novel framework for multi-physics numerical simulations of the star-forming interstellar medium (ism) implemented in the athena mhd code. the algorithms of tigress are designed to spatially and temporally resolve key physical features, including: (1) the gravitational collapse and ongoing accretion of gas that leads to star formation in clusters; (2) the explosions of supernovae (sne), both near their progenitor birth sites and from runaway ob stars, with time delays relative to star formation determined by population synthesis; (3) explicit evolution of sn remnants prior to the onset of cooling, which leads to the creation of the hot ism; (4) photoelectric heating of the warm and cold phases of the ism that tracks the time-dependent ambient fuv field from the young cluster population; (5) large-scale galactic differential rotation, which leads to epicyclic motion and shears out overdense structures, limiting large-scale gravitational collapse; (6) accurate evolution of magnetic fields, which can be important for vertical support of the ism disk as well as angular momentum transport. we present tests of the newly implemented physics modules, and demonstrate application of tigress in a fiducial model representing the solar neighborhood environment. we use a resolution study to demonstrate convergence and evaluate the minimum resolution {{δ }}x required to correctly recover several ism properties, including the star formation rate, wind mass-loss rate, disk scale height, turbulent and alfvénic velocity dispersions, and volume fractions of warm and hot phases. for the solar neighborhood model, all these ism properties are converged at {{δ }}x≤slant 8 {pc}. | three-phase interstellar medium in galaxies resolving evolution with star formation and supernova feedback (tigress): algorithms, fiducial model, and convergence |
interaction-powered supernovae (sne) explode within an optically thick circumstellar medium (csm) that could be ejected during eruptive events. to identify and characterize such pre-explosion outbursts, we produce forced-photometry light curves for 196 interacting sne, mostly of type iin, detected by the zwicky transient facility between early 2018 and 2020 june. extensive tests demonstrate that we only expect a few false detections among the 70,000 analyzed pre-explosion images after applying quality cuts and bias corrections. we detect precursor eruptions prior to 18 type iin sne and prior to the type ibn sn 2019uo. precursors become brighter and more frequent in the last months before the sn and month-long outbursts brighter than magnitude -13 occur prior to 25% (5-69%, 95% confidence range) of all type iin sne within the final three months before the explosion. with radiative energies of up to 1049 erg, precursors could eject ∼1 m⊙ of material. nevertheless, sne with detected precursors are not significantly more luminous than other sne iin, and the characteristic narrow hydrogen lines in their spectra typically originate from earlier, undetected mass-loss events. the long precursor durations require ongoing energy injection, and they could, for example, be powered by interaction or by a continuum-driven wind. instabilities during the neon- and oxygen-burning phases are predicted to launch precursors in the final years to months before the explosion; however, the brightest precursor is 100 times more energetic than anticipated. | bright, months-long stellar outbursts announce the explosion of interaction-powered supernovae |
we present a set of multiwavelength mosaics and photometric catalogs in the atacama large millimeter/submillimeter array (alma) lensing cluster survey fields. the catalogs were built by the reprocessing of archival data from the complete hubble archive for galaxy evolution compilation, taken by the hubble space telescope (hst) in the reionization lensing cluster survey, cluster lensing and supernova survey with hubble, and hubble frontier fields. additionally, we have reconstructed the spitzer infrared array camera 3.6 and 4.5 μm mosaics, by utilizing all the available archival ipac infrared science archive/spitzer heritage archive exposures. to alleviate the effect of blending in such a crowded region, we have modeled the spitzer photometry by convolving the hst detection image with the spitzer point-spread function using the novel golfir software. the final catalogs contain 218,000 sources, covering a combined area of 690 arcmin2, a factor of ~2 improvement over the currently existing photometry. a large number of detected sources is a result of reprocessing of all available and sometimes deeper exposures, in conjunction with a combined optical-near-ir detection strategy. these data will serve as an important tool in aiding the search of the submillimeter galaxies in future alma surveys, as well as follow-ups of the hst dark and high-z sources with jwst. coupled with the available hst photometry, the addition of the 3.6 and 4.5 μm bands will allow us to place a better constraint on the photometric redshifts and stellar masses of these objects, thus giving us an opportunity to identify high-redshift candidates for spectroscopic follow-ups and to answer the important questions regarding the epoch of reionization and formation of the first galaxies. the mosaics, photometric catalogs, and the best-fit physical properties are publicly available at https://github.com/dawn-cph/alcs-clusters. | alma lensing cluster survey: hubble space telescope and spitzer photometry of 33 lensed fields built with charge |
we wish to investigate whether there is an extension to the base λcdm cosmology that can resolve the tension between the planck observation of the cosmic microwave background anisotropies and the local measurement of the hubble constant. we consider various plausible extended models in this work, and we use the planck 2015 observations, combined with the baryon acoustic oscillation data, the jla type ia supernovae data, and the local measurement of the hubble constant (by riess et al. in 2016), to make an analysis. we find that the holographic dark energy plus sterile neutrino model can reduce the tension to be at the 1.11σ level, but this model is obviously not favored by the current observations. among these extended models, the λcdm+neff model is most favored by the current observations, and this model can reduce the tension to be at the 1.87σ level. by a careful test, we conclude that none of these extended models can convincingly resolve the h0 tension. | can the h0 tension be resolved in extensions to λcdm cosmology? |
new developments in liquid scintillators, high-efficiency, fast photon detectors, and chromatic photon sorting have opened up the possibility for building a large-scale detector that can discriminate between cherenkov and scintillation signals. such a detector could reconstruct particle direction and species using cherenkov light while also having the excellent energy resolution and low threshold of a scintillator detector. situated deep underground, and utilizing new techniques in computing and reconstruction, this detector could achieve unprecedented levels of background rejection, enabling a rich physics program spanning topics in nuclear, high-energy, and astrophysics, and across a dynamic range from hundreds of kev to many gev. the scientific program would include observations of low- and high-energy solar neutrinos, determination of neutrino mass ordering and measurement of the neutrino cp-violating phase δ , observations of diffuse supernova neutrinos and neutrinos from a supernova burst, sensitive searches for nucleon decay and, ultimately, a search for neutrinoless double beta decay, with sensitivity reaching the normal ordering regime of neutrino mass phase space. this paper describes uc(theia), a detector design that incorporates these new technologies in a practical and affordable way to accomplish the science goals described above. | uc(theia): an advanced optical neutrino detector |
we investigate the impact of stellar rotation on the formation of black holes (bhs) by means of our population synthesis code sevn. rotation affects the mass function of bhs in several ways. in massive metal-poor stars, fast rotation reduces the minimum zero-age main sequence (zams) mass for a star to undergo pair instability and pulsational pair instability. moreover, stellar winds are enhanced by rotation, peeling off the entire hydrogen envelope. as a consequence of these two effects, the maximum bh mass we expect from the collapse of a rotating metal-poor star is only ∼45 m ⊙, while the maximum mass of a bh born from a nonrotating star is ∼60 m ⊙. furthermore, stellar rotation reduces the minimum zams mass for a star to collapse into a bh from ∼18-25 m ⊙ to ∼13-18 m ⊙. finally, we have investigated the impact of different core-collapse supernova (ccsn) prescriptions on our results. while the threshold value of compactness for direct collapse and the fallback efficiency strongly affect the minimum zams mass for a star to collapse into a bh, the fraction of the hydrogen envelope that can be accreted onto the final bh is the most important ingredient in determining the maximum bh mass. our results confirm that the interplay between stellar rotation, ccsne and pair instability plays a major role in shaping the bh mass spectrum. | impact of the rotation and compactness of progenitors on the mass of black holes |
studies of dark energy at advanced gravitational-wave (gw) interferometers normally focus on the dark energy equation of state wde(z ). however, modified gravity theories that predict a nontrivial dark energy equation of state generically also predict deviations from general relativity in the propagation of gws across cosmological distances, even in theories where the speed of gravity is equal to c . we find that, in generic modified gravity models, the effect of modified gw propagation dominates over that of wde(z ), making modified gw propagation a crucial observable for dark energy studies with standard sirens. we present a convenient parametrization of the effect in terms of two parameters (ξ0,n ), analogue to the (w0,wa) parametrization of the dark energy equation of state, and we give a limit from the ligo/virgo measurement of h0 with the neutron star binary gw170817. we then perform a markov chain monte carlo analysis to estimate the sensitivity of the einstein telescope (et) to the cosmological parameters, including (ξ0,n ), both using only standard sirens, and combining them with other cosmological data sets. in particular, the hubble parameter can be measured with an accuracy better than 1% already using only standard sirens while, when combining et with current cmb +bao +sne data, ξ0 can be measured to 0.8%. we discuss the predictions for modified gw propagation of a specific nonlocal modification of gravity, recently developed by our group, and we show that they are within the reach of et. modified gw propagation also affects the gw transfer function, and therefore the tensor contribution to the isw effect. | modified gravitational-wave propagation and standard sirens |
we present final natural-system optical (ugribv) and near-infrared (yjh) photometry of 134 supernovae (sne) with probable white dwarf progenitors that were observed in 2004-2009 as part of the first stage of the carnegie supernova project (csp-i). the sample consists of 123 type ia sne, 5 type iax sne, 2 super-chandrasekhar sn candidates, 2 type ia sne interacting with circumstellar matter, and 2 sn 2006bt-like events. the redshifts of the objects range from z=0.0037 to 0.0835; the median redshift is 0.0241. for 120 (90%) of these sne, near-infrared photometry was obtained. average optical extinction coefficients and color terms are derived and demonstrated to be stable during the five csp-i observing campaigns. measurements of the csp-i near-infrared bandpasses are also described, and near-infrared color terms are estimated through synthetic photometry of stellar atmosphere models. optical and near-infrared magnitudes of local sequences of tertiary standard stars for each supernova are given, and a new calibration of y-band magnitudes of the persson et al. standards in the csp-i natural system is presented. | the carnegie supernova project. i. third photometry data release of low-redshift type ia supernovae and other white dwarf explosions |
progenitor models for the "luminous" subclass of fast blue optical transients (lfbots; prototype: at2018cow) are challenged to simultaneously explain all of their observed properties: fast optical rise times of days or less; peak luminosities ≳1044 erg s-1; low yields ≲0.1m ⊙ of 56ni; aspherical ejecta with a wide velocity range (≲3000 km s-1 to ≳0.1-0.5c with increasing polar latitude); presence of hydrogen-depleted-but-not-free dense circumstellar material (csm) on radial scales from ~1014 cm to ~3 × 1016 cm; embedded variable source of non-thermal x-ray/γ-rays, suggestive of a compact object. we show that all of these properties are consistent with the tidal disruption and hyper-accretion of a wolf-rayet (wr) star by a black hole or neutron star binary companion. in contrast with related previous models, the merger occurs with a long delay (≳100 yr) following the common envelope (ce) event responsible for birthing the binary, as a result of gradual angular momentum loss to a relic circumbinary disk. disk-wind outflows from the merger-generated accretion flow generate the 56ni-poor aspherical ejecta with the requisite velocity range. the optical light curve is powered primarily by reprocessing x-rays from the inner accretion flow/jet, though csm shock interaction also contributes. primary csm sources include wr mass loss from the earliest stages of the merger (≲1014 cm) and the relic ce disk and its photoevaporation-driven wind (≳1016 cm). longer delayed mergers may instead give rise to supernovae type ibn/icn (depending on the wr evolutionary state), connecting these transient classes with lfbots. | luminous fast blue optical transients and type ibn/icn sne from wolf-rayet/black hole mergers |
in the present work, the optical properties of polyvinyl alcohol (pva)/polyvinyl pyrrolidone (pvp) (1:1) polymeric blend have been tuned in situ using tin sulfide (sns) semiconductor for optoelectronics. the solution casting technique was used to prepare plain pva/pvp polymeric blend and different weight ratios percentages (x: 0, 0.1, 0.5, 1.0, 5.0 and 10.0 wt%) of sns filled pva/pvp polymeric blend nanocomposite films. the prepared films were characterized using a scanning electron microscope, x-ray diffractometer, ft-ir spectroscopic technique and uv-visible-nir spectrophotometer. the effect of sns concentration on the optical parameters (optical energy gap, refractive index, optical conductivity, dielectric constants, dispersion energy and average oscillator strength) has been investigated. the ability to tune the optical parameters of the prepared sns nanocomposite polymeric blend films makes them effective candidates in many applications especially optoelectronics and optical devices. | engineering the optical properties of pva/pvp polymeric blend in situ using tin sulfide for optoelectronics |
in 1964, refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. we report the discovery of such a system. in hubble space telescope imaging, we have found four images of a single supernova forming an einstein cross configuration around a redshift z = 0.54 elliptical galaxy in the macs j1149.6+2223 cluster. the cluster’s gravitational potential also creates multiple images of the z = 1.49 spiral supernova host galaxy, and a future appearance of the supernova elsewhere in the cluster field is expected. the magnifications and staggered arrivals of the supernova images probe the cosmic expansion rate, as well as the distribution of matter in the galaxy and cluster lenses. | multiple images of a highly magnified supernova formed by an early-type cluster galaxy lens |
in this paper, we investigate a recent proposed model - so called the tsallis holographic dark energy (thde) model with consideration of the hubble and the event future horizon as ir cutoffs. in this case, we consider the non-gravitational and phenomenological interaction between dark sectors. we fit the free parameters of the model using pantheon supernovae type ia data, baryon acoustic oscillations, cosmic microwave background, gamma-ray burst and the the local value of the hubble constant. we examine the thde model to check its compatibility with observational data using objective information criterion (ic). we find that the thde models cannot be supported by observational data once the λ cdm is considered as the referring model. therefore we re-examine the analysis with the standard holographic dark energy model (hde) as another reference. changing the λ cdm to main standard dark energy model (hde), we observe the compatibility of the thde models. using the alcock-paczynski (ap) test we check the deviation of the model compared to λ cdm and hde. surveying the evolution of squared of sound speed v^2_s as an another test we check the stability of the interacting and non-interacting thde models and we find that while the thde model with the hubble horizon as ir cutoff is unstable against the background perturbation, the future event horizon as ir cutoff show stability at the late time. in addition, using the modified version of the camb package, we observe the suppressing the cmb spectrum at small k-modes and large scale. | observational constraints on interacting tsallis holographic dark energy model |
feedback from massive stars plays a key role in molecular cloud evolution. after the onset of star formation, the young stellar population is exposed by photoionization, winds, supernovae, and radiation pressure from massive stars. recent observations of nearby galaxies have provided the evolutionary timeline between molecular clouds and exposed young stars, but the duration of the embedded phase of massive star formation is still ill-constrained. we measure how long massive stellar populations remain embedded within their natal cloud, by applying a statistical method to six nearby galaxies at $20{-}100~\mbox{${\rm ~pc}$}$ resolution, using co, spitzer 24$\rm \, \mu m$, and h α emission as tracers of molecular clouds, embedded star formation, and exposed star formation, respectively. we find that the embedded phase (with co and 24$\rm \, \mu m$ emission) lasts for 2-7 myr and constitutes $17{-}47{{\ \rm per\ cent}}$ of the cloud lifetime. during approximately the first half of this phase, the region is invisible in h α, making it heavily obscured. for the second half of this phase, the region also emits in h α and is partially exposed. once the cloud has been dispersed by feedback, 24$\rm \, \mu m$ emission no longer traces ongoing star formation, but remains detectable for another 2-9 myr through the emission from ambient co-dark gas, tracing star formation that recently ended. the short duration of massive star formation suggests that pre-supernova feedback (photoionization and winds) is important in disrupting molecular clouds. the measured time-scales do not show significant correlations with environmental properties (e.g. metallicity). future jwst observations will enable these measurements routinely across the nearby galaxy population. | on the duration of the embedded phase of star formation |
during the first three observing runs of the advanced gravitational-wave detector network, the ligo/virgo collaboration detected several black hole binary (bhbh) mergers. as the population of detected bhbh mergers grows, it will become possible to constrain different channels for their formation. here we consider the chemically homogeneous evolution (che) channel in close binaries, by performing population synthesis simulations that combine realistic binary models with detailed cosmological calculations of the chemical and star-formation history of the universe. this allows us to constrain population properties, as well as cosmological and aligo/avirgo detection rates of bhbh mergers formed through this pathway. we predict a bhbh merger rate at redshift zero of $5.8 \textrm {gpc}^{-3} \textrm {yr}^{-1}$ through the che channel, to be compared with aligo/avirgo's measured rate of ${53.2}_{-28.2}^{+55.8} \text{gpc}^{-3}\text{yr}^{-1}$ , and find that eventual merger systems have bh masses in the range $17{-}43 \,\textrm {m}_{\odot }$ below the pair-instability supernova (pisn) gap, and ${\gt}124 \textrm {m}_{\odot }$ above the pisn gap. we investigate effects of momentum kicks during black hole formation, and calculate cosmological and magnitude limited pisn rates. we also study the effects of high-redshift deviations in the star formation rate. we find that momentum kicks tend to increase delay times of bhbh systems, and our magnitude limited pisn rate estimates indicate that current deep surveys should be able to detect such events. lastly, we find that our cosmological merger rate estimates change by at most ${\sim}8{{\ \rm per\ cent}}$ for mild deviations of the star formation rate in the early universe, and by up to ${\sim}40\,\text{per cent}$ for extreme deviations. | cosmic rates of black hole mergers and pair-instability supernovae from chemically homogeneous binary evolution |
we present the fourth simulation of the cholla galactic outflow simulations suite. using a physically motivated prescription for clustered supernova feedback, we successfully drive a multiphase outflow from a disk galaxy. the high resolution (<5 pc) across a relatively large domain (20 kpc) allows us to capture the hydrodynamic mixing and dynamical interactions between the hot and cool (t ∼ 104 k) phases in the outflow, which in turn leads to direct evidence of a qualitatively new mechanism for cool gas acceleration in galactic winds. we show that mixing of momentum from the hot phase to the cool phase accelerates the cool gas to 800 km s-1 on kiloparsec scales, with properties inconsistent with the physical models of ram pressure acceleration or bulk cooling from the hot phase. the mixing process also affects the hot phase, modifying its radial profiles of temperature, density, and velocity from the expectations of radial supersonic flow. this mechanism provides a physical explanation for the high-velocity, blueshifted, low-ionization absorption lines often observed in the spectra of starburst and high-redshift galaxies. | the physical nature of starburst-driven galactic outflows |
over the last years some interest has been gathered by f (q ) theories, which are new candidates to replace einstein's prescription for gravity. the nonmetricity tensor q allows to put forward the assumption of a free torsionless connection and, consequently, new degrees of freedom in the action are taken into account. this work focuses on a class of f (q ) theories, characterized by the presence of a general power-law term which adds up to the standard (linear in) q term in the action, and on new cosmological scenarios arising from them. using the markov chain monte carlo method, we carry out statistical tests relying upon background data such as type ia supernovae luminosities and direct hubble data (from cosmic clocks), along with cosmic microwave background shift and baryon acoustic oscillations data. this allows us to perform a multifaceted comparison between these new cosmologies and the (concordance) λ cdm setup. we conclude that, at the current precision level, the best fits of our f (q ) models correspond to values of their specific parameters which make them hardly distinguishable from our general relativity "échantillon," that is, λ cdm . | observational constraints on cosmological solutions of f (q ) theories |
i present a set of long-term, direct, relativistic many-body computations of model dense stellar clusters with up-to-date stellar-evolutionary, supernova (sn), and remnant natal-kick models, including pair instability and pulsation pair instability supernova (psn and ppsn), using an updated version of ${\rm{\small nbody7}}$ n-body simulation program. the n-body model also includes stellar evolution-based natal spins of black holes (bhs) and treatments of binary black hole (bbh) mergers based on numerical relativity. these, for the first time in a direct n-body simulation, allow for second-generation bbh mergers. the set of 65 evolutionary models have initial masses $10^4{\!-\!}10^5\, \mathrm{m}_{\odot }$ , sizes 1-3 pc, metallicity 0.0001-0.02, with the massive stars in primordial binaries and they represent young massive clusters (ymc) and moderately massive open clusters (oc). such models produce dynamically paired bbh mergers that agree well with the observed masses, mass ratios, effective spin parameters, and final spins of the lvc o1/o2 merger events, provided bhs are born with low or no spin but spin-up after undergoing a bbh merger or matter accretion on to it. in particular, the distinctly higher mass, effective spin parameter, and final spin of gw170729 merger event is naturally reproduced, as also the mass asymmetry of the o3 event gw190412. the computed models produce intermediate-mass, $\sim 100\, \mathrm{m}_{\odot }$ bbh mergers with primary mass within the 'psn gap' and also yield mergers involving remnants in the 'mass gap'. they also suggest that ymcs and ocs produce persistent, local-universe gw sources detectable by lisa. such clusters are also capable of producing eccentric ligo-virgo mergers. | stellar-mass black holes in young massive and open stellar clusters - iv. updated stellar-evolutionary and black hole spin models and comparisons with the ligo-virgo o1/o2 merger-event data |
the era of large transient surveys, gravitational-wave observatories, and multi-messenger astronomy has opened up new possibilities for our understanding of the evolution and final fate of massive stars. most massive stars are born in binary or higher-order multiple systems and exchange mass with a companion star during their lives. in particular, the progenitors of a large fraction of compact-object mergers, and galactic neutron stars (nss) and black holes (bhs) have been stripped of their envelopes by a binary companion. here, we study the evolution of single and stripped binary stars up to core collapse with the stellar evolution code mesa and their final fates with a parametric supernova (sn) model. we find that stripped binary stars can have systematically different pre-sn structures compared to genuine single stars and thus also different sn outcomes. these differences are already established by the end of core helium burning and are preserved up to core collapse. consequently, we find that case a and b stripped stars and single and case c stripped stars develop qualitatively similar pre-sn core structures. we find a non-monotonic pattern of ns and bh formation as a function of co core mass that is different in single and stripped binary stars. in terms of initial mass, single stars of ≳35 m⊙ all form bhs, while this transition is only at about 70 m⊙ in stripped stars. on average, stripped stars give rise to lower ns and bh masses, higher explosion energies, higher kick velocities, and higher nickel yields. within a simplified population-synthesis model, we show that our results lead to a significant reduction in the rates of bh-ns and bh-bh mergers with respect to typical assumptions made on ns and bh formation. therefore, our models predict lower detection rates of such merger events with for example the advanced laser interferometer gravitational-wave observatory (ligo) than is often considered. further, we show how certain features in the ns-bh mass distribution of single and stripped stars relate to the chirp-mass distribution of compact object mergers. further implications of our findings are discussed with respect to the missing red-supergiant problem, a possible mass gap between nss and bhs, x-ray binaries, and observationally inferred nickel masses from type ib/c and iip sne. | pre-supernova evolution, compact-object masses, and explosion properties of stripped binary stars |
the most precise local measurements of h0 rely on observations of type ia supernovae (sne ia) coupled with cepheid distances to sn ia host galaxies. recent results have shown tension comparing h0 to the value inferred from cmb observations assuming λcdm, making it important to check for potential systematic uncertainties in either approach. to date, precise local h0 measurements have used sn ia distances based on optical photometry, with corrections for light curve shape and colour. here, we analyse sne ia as standard candles in the near-infrared (nir), where luminosity variations in the supernovae and extinction by dust are both reduced relative to the optical. from a combined fit to 9 nearby calibrator sne with host cepheid distances from riess et al. (2016) and 27 sne in the hubble flow, we estimate the absolute peak j magnitude mj = -18.524 ± 0.041 mag and h0 = 72.8 ± 1.6 (statistical) ±2.7 (systematic) km s-1 mpc-1. the 2.2% statistical uncertainty demonstrates that the nir provides a compelling avenue to measuring sn ia distances, and for our sample the intrinsic (unmodeled) peak j magnitude scatter is just 0.10 mag, even without light curve shape or colour corrections. our results do not vary significantly with different sample selection criteria, though photometric calibration in the nir may be a dominant systematic uncertainty. our findings suggest that tension in the competing h0 distance ladders is likely not a result of supernova systematics that could be expected to vary between optical and nir wavelengths, like dust extinction. we anticipate further improvements in h0 with a larger calibrator sample of sne ia with cepheid distances, more hubble flow sne ia with nir light curves, and better use of the full nir photometric data set beyond simply the peak j-band magnitude. | measuring the hubble constant with type ia supernovae as near-infrared standard candles |
low-mass galaxies are thought to provide the bulk of the ionizing radiation necessary to reionize the universe. the amount of photons escaping the galaxies is poorly constrained theoretically, and difficult to measure observationally. yet it is an essential parameter of reionization models. we study in detail how ionizing radiation can leak from high-redshift galaxies. for this purpose, we use a series of high-resolution radiation hydrodynamics simulations, zooming on three dwarf galaxies in a cosmological context. we find that the energy and momentum input from the supernova explosions has a pivotal role in regulating the escape fraction by disrupting dense star-forming clumps, and clearing sightlines in the halo. in the absence of supernovae, photons are absorbed very locally, within the birth clouds of massive stars. we follow the time evolution of the escape fraction and find that it can vary by more than six orders of magnitude. this explains the large scatter in the value of the escape fraction found by previous studies. this fast variability also impacts the observability of the sources of reionization: a survey even as deep as m1500 = -14 would miss about half of the underlying population of lyman-continuum emitters. | fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies |
we introduce the 'engineering dwarfs at galaxy formation's edge' (edge) project to study the cosmological formation and evolution of the smallest galaxies in the universe. in this first paper, we explore the effects of resolution and sub-grid physics on a single low-mass halo (m_halo=109{ m}_⊙), simulated to redshift z = 0 at a mass and spatial resolution of ∼ 20{ m}_⊙ and ∼3 pc. we consider different star formation prescriptions, supernova feedback strengths, and on-the-fly radiative transfer (rt). we show that rt changes the mode of galactic self-regulation at this halo mass, suppressing star formation by causing the interstellar and circumgalactic gas to remain predominantly warm (∼104 k) even before cosmic reionization. by contrast, without rt, star formation regulation occurs only through starbursts and their associated vigorous galactic outflows. in spite of this difference, the entire simulation suite (with the exception of models without any feedback) matches observed dwarf galaxy sizes, velocity dispersions, v-band magnitudes, and dynamical mass-to-light-ratios. this is because such structural scaling relations are predominantly set by the host dark matter halo, with the remaining model-to-model variation being smaller than the observational scatter. we find that only the stellar mass-metallicity relation differentiates the galaxy formation models. explosive feedback ejects more metals from the dwarf, leading to a lower metallicity at a fixed stellar mass. we conclude that the stellar mass-metallicity relation of the very smallest galaxies provides a unique constraint on galaxy formation physics. | edge: the mass-metallicity relation as a critical test of galaxy formation physics |
existing models for the dependence of the halo mass function on cosmological parameters will become a limiting source of systematic uncertainty for cluster cosmology in the near future. we present a halo mass function emulator and demonstrate improved accuracy relative to state-of-the-art analytic models. in this work, mass is defined using an overdensity criteria of 200 relative to the mean background density. our emulator is constructed from the aemulus simulations, a suite of 40 n-body simulations with snapshots from z = 3 to z = 0. these simulations cover the flat wcdm parameter space allowed by recent cosmic microwave background, baryon acoustic oscillation and sne ia results, varying the parameters w, ω m , ω b , σ 8, n eff, ns , and h 0. we validate our emulator using five realizations of seven different cosmologies, for a total of 35 test simulations. these test simulations were not used in constructing the emulator, and were run with fully independent initial conditions. we use our test simulations to characterize the modeling uncertainty of the emulator, and introduce a novel way of marginalizing over the associated systematic uncertainty. we confirm nonuniversality in our halo mass function emulator as a function of both cosmological parameters and redshift. our emulator achieves better than 1% precision over much of the relevant parameter space, and we demonstrate that the systematic uncertainty in our emulator will remain a negligible source of error for cluster abundance studies through at least the lsst year 1 data set. | the aemulus project. ii. emulating the halo mass function |
we present the analysis underpinning the measurement of cosmological parameters from 207 spectroscopically classified sne ia from the first 3 years of the dark energy survey supernova program (des-sn), spanning a redshift range of 0.017 < z < 0.849. we combine the des-sn sample with an external sample of 122 low-redshift (z < 0.1) sne ia, resulting in a “des-sn3yr” sample of 329 sne ia. our cosmological analyses are blinded: after combining our des-sn3yr distances with constraints from the cosmic microwave background, our uncertainties in the measurement of the dark energy equation-of-state parameter, w, are 0.042 (stat) and 0.059 (stat+syst) at 68% confidence. we provide a detailed systematic uncertainty budget, which has nearly equal contributions from photometric calibration, astrophysical bias corrections, and instrumental bias corrections. we also include several new sources of systematic uncertainty. while our sample is less than one-third the size of the pantheon sample, our constraints on w are only larger by 1.4×, showing the impact of the des-sn ia light-curve quality. we find that the traditional stretch and color standardization parameters of the des-sne ia are in agreement with earlier sn ia samples such as pan-starrs1 and the supernova legacy survey. however, we find smaller intrinsic scatter about the hubble diagram (0.077 mag). interestingly, we find no evidence for a hubble residual step (0.007 ± 0.018 mag) as a function of host-galaxy mass for the des subset, in 2.4σ tension with previous measurements. we also present novel validation methods of our sample using simulated sne ia inserted in decam images and using large catalog-level simulations to test for biases in our analysis pipelines. | first cosmology results using sne ia from the dark energy survey: analysis, systematic uncertainties, and validation |
short gamma-ray bursts (grbs) are explosions of cosmic origins believed to be associated with the merger of two compact objects, either two neutron stars or a neutron star and a black hole (bh). the presence of at least one neutron star has long been thought to be an essential element of the model: its tidal disruption provides the needed baryonic material whose rapid accretion onto the post-merger bh powers the burst. the recent tentative detection by the fermi satellite of a short grb in association with the gravitational wave signal gw150914 produced by the merger of two bhs has challenged this standard paradigm. here, we show that the evolution of two high-mass, low-metallicity stars with main-sequence rotational speeds a few tens of percent of the critical speed eventually undergoing a weak supernova explosion can produce a short grb. the outer layers of the envelope of the last exploding star remain bound and circularize at large radii. with time, the disk cools and becomes neutral, suppressing the magnetorotational instability, and hence the viscosity. the disk remains “long-lived dead” until tidal torques and shocks during the pre-merger phase heat it up and re-ignite accretion, rapidly consuming the disk and powering the short grb. | short gamma-ray bursts from the merger of two black holes |
we investigate r-process nucleosynthesis in 3d general-relativistic magnetohydrodynamic simulations of rapidly rotating strongly magnetized core collapse. the simulations include a microphysical finite-temperature equation of state and a leakage scheme that captures the overall energetics and lepton number exchange due to postbounce neutrino emission and absorption. we track the composition of the ejected material using the nuclear reaction network skynet. our results show that the 3d dynamics of magnetorotational core-collapse supernovae (ccsn) are important for their nucleosynthetic signature. we find that production of r-process material beyond the second peak is reduced by a factor of 100 when the magnetorotational jets produced by the rapidly rotating core undergo a kink instability. our results indicate that 3d magnetorotationally powered ccsne are robust r-process sources only if they are obtained by the collapse of cores with unrealistically large precollapse magnetic fields of the order of 1013 g. additionally, a comparison simulation that we restrict to axisymmetry results in overly optimistic r-process production for lower magnetic field strengths. | r-process nucleosynthesis from three-dimensional magnetorotational core-collapse supernovae |
we extend the analysis of a physical model within the standard cosmology that robustly predicts a high star-formation efficiency (sfe) in massive galaxies at cosmic dawn due to feedback-free starbursts (ffb). it implies an excess of bright galaxies at z>~10 compared to the standard models based on the low sfe at later epochs, an excess that is indicated by jwst observations. here we provide observable predictions based on the analytic ffb scenario, to be compared with simulations and jwst observations. we use the model to approximate the sfe as a function of redshift and mass, assuming a maximum sfe of 0.2~1 in the ffb regime. from this, we derive the evolution of the galaxy mass and luminosity functions as well as the evolution of stellar and star-formation densities. we then predict the star-formation history (sfh), galaxy sizes, outflows, gas fractions, metallicities and dust attenuation, all as functions of mass and redshift in the ffb regime. the major distinguishing feature is the occurrence of ffbs above a mass threshold that declines with redshift. the luminosities and star formation rates in bright galaxies are predicted to be in excess of extrapolations of standard empirical models and cosmological simulations, an excess that grows from z~9 to higher redshifts. the ffb phase of ~100myr is predicted to show a characteristic sfh that fluctuates on a timescale of ~10myr. the stellar systems are compact (re~0.3kpc at z~10 and declining with z). the galactic gas consists of a steady wind driven by supernovae from earlier generations, with high outflow velocities (fwhm~1400-6700km/s), low gas fractions (<0.1), low metallicities (<~0.1solar), and low dust attenuation ($a_{uv}$~0.5 at z~10 and declining with z). tentative comparisons with current jwst observations are made for preliminary impression, to be performed quantitatively when more complete reliable data become available. | feedback-free starbursts at cosmic dawn: observable predictions for jwst |
shock breakout emission is light that arises when a shockwave, generated by core-collapse explosion of a massive star, passes through its outer envelope. hitherto, the earliest detection of such a signal was at several hours after the explosion, though a few others had been reported. the temporal evolution of early light curves should reveal insights into the shock propagation, including explosion asymmetry and environment in the vicinity, but this has been hampered by the lack of multiwavelength observations. here we report the instant multiband observations of a type ii supernova (sn 2023ixf) in the galaxy m101 (at a distance of 6.85+/-0.15 mpc), beginning at about 1.4 hours after the explosion. the exploding star was a red supergiant with a radius of about 440 solar radii. the light curves evolved rapidly, on timescales of 1-2 hours, and appeared unusually fainter and redder than predicted by models within the first few hours, which we attribute to an optically thick dust shell before it was disrupted by the shockwave. we infer that the breakout and perhaps the distribution of the surrounding dust were not spherically symmetric. | a shock flash breaking out of a dusty red supergiant |
we consider a low redshift (z <0.7 ) cosmological data set comprising megamasers, cosmic chronometers, type ia supernovae and baryon acoustic oscillations, which we bin according to their redshift. for each bin, we read the value of h0 by fitting directly to the flat λ cdm model. doing so, we find that h0 descends with redshift, allowing one to fit a line with a nonzero slope of statistical significance 2.1 σ . our analysis rests on the use of cosmic chronometers to break a degeneracy in baryon acoustic oscillations data and it will be imperative to revisit this feature as data improves. nevertheless, our results provide the first independent indication of the descending trend reported by the h0licow collaboration. if substantiated going forward, early universe solutions to the hubble tension will struggle explaining this trend. | is there an early universe solution to hubble tension? |
the rapidly growing statistical precision of galaxy surveys has led to a need for ever more precise predictions of the observables used to constrain cosmological and galaxy formation models. the primary avenue through which such predictions will be obtained is suites of numerical simulations. these simulations must span the relevant model parameter spaces, be large enough to obtain the precision demanded by upcoming data, and be thoroughly validated in order to ensure accuracy. in this paper, we present one such suite of simulations, forming the basis for the aemulus project, a collaboration devoted to precision emulation of galaxy survey observables. we have run a set of 75 (1.05 h -1 gpc)3 simulations with mass resolution and force softening of 3.51× {10}10≤ft({{{ω }}}m/0.3\right) {h}-1 {m}⊙and 20 h -1 kpc, respectively, in 47 different wcdm cosmologies spanning the range of parameter space allowed by the combination of recent cosmic microwave background, baryon acoustic oscillation, and type ia supernova results. we present convergence tests of several observables including spherical overdensity halo mass functions, galaxy projected correlation functions, galaxy clustering in redshift space, and matter and halo correlation functions and power spectra. we show that these statistics are converged to 1% (2%) or to the sample variance of the statistic, whichever is larger, for halos with more than 500 (200) particles, respectively, and scales of r > 200 h -1 kpc in real space or k ∼ 3 h mpc-1 in harmonic space for z ≤ 1. we find that the dominant source of uncertainty comes from varying the particle loading of the simulations. this leads to large systematic errors for statistics using halos with fewer than 200 particles and scales smaller than k ∼ 4 h mpc-1. we provide the halo catalogs and snapshots detailed in this work to the community at https://aemulusproject.github.io. | the aemulus project. i. numerical simulations for precision cosmology |
reliable indirect diagnostics of lyc photon escape from galaxies are required to understand which sources were the dominant contributors to reionization. while multiple escape fraction ($f_{\rm esc}$) indicators have been proposed to trace favourable conditions for lyc leakage from the interstellar medium of low-redshift ``analog'' galaxies, it remains unclear whether these are applicable at high redshifts where lyc emission cannot be directly observed. using a library of 14,120 mock spectra of star-forming galaxies with redshifts $4.64 \leq z \leq 10$ from the sphinx$^{20}$ cosmological radiation hydrodynamics simulation, we develop a framework for the physics that leads to high $f_{\rm esc}$. we investigate lyc leakage from our galaxies based on the criteria that successful lyc escape diagnostics must \textit{i)} track a high specific star formation rate, \textit{ii)} be sensitive to stellar population age in the range $3.5-10$~myr representing the times when supernova first explode to when lyc production significantly drops, and \textit{iii)} include a proxy for neutral gas content and gas density in the interstellar medium. ${\rm o}_{32}$, $\sigma_{\rm sfr}$, m$_{\rm uv}$, and h$\beta$ equivalent width select for one or fewer of our criteria, rendering them either necessary but insufficient or generally poor diagnostics. in contrast, uv slope ($\beta$), and ${\rm e(b-v)}$ match two or more of our criteria, rendering them good $f_{\rm esc}$ diagnostics (albeit with significant scatter). using our library, we build a quantitative model for predicting $f_{\rm esc}$ based on $\beta$, ${\rm e(b-v)}$, h$\beta$, m$_{\rm uv}$, ${\rm r_{23}}$, and ${\rm o_{32}}$. when applied to bright $z > 6$ ly$\alpha$ emitters observed with jwst, we find that the majority of them have $f_{\rm esc} \lesssim 10\%$. | the physics of indirect estimators of lyman continuum escape and their application to high-redshift jwst galaxies |
we present a new subgrid model for neutrino quantum kinetics, which is primarily designed to incorporate effects of collective neutrino oscillations into neutrino-radiation-hydrodynamic simulations for core-collapse supernovae and mergers of compact objects. we approximate the neutrino oscillation term in quantum kinetic equation by bhatnagar-gross-krook (bgk) relaxation-time prescription, and the transport equation is directly applicable for classical neutrino transport schemes. the bgk model is motivated by recent theoretical indications that non-linear phases of collective neutrino oscillations settle into quasi-steady structures. we explicitly provide basic equations of the bgk subgrid model for both multi-angle and moment-based neutrino transport to facilitate the implementation of the subgrid model in the existing neutrino transport schemes. we also show the capability of our bgk subgrid model by comparing to fully quantum kinetic simulations for fast neutrino-flavor conversion. we find that the overall properties can be well reproduced in the subgrid model; the error of angular-averaged survival probability of neutrinos is within $\sim 20 \%$. by identifying the source of error, we also discuss perspectives to improve the accuracy of the subgrid model. | bgk subgrid model for neutrino quantum kinetics |
synthesized in the cores of stars and supernovae, most metals disperse over cosmic scales and are ultimately deposited well outside the gravitational potential of their host galaxies. since their presence is well visible through their x-ray emission lines in the hot gas pervading galaxy clusters, measuring metal abundances in the intracluster medium (icm) offers us a unique view of chemical enrichment of the universe as a whole. despite extraordinary progress in the field thanks to four decades of x-ray spectroscopy using ccd (and gratings) instruments, understanding the precise stellar origins of the bulk of metals, and when the latter were mixed on mpc scales, requires an x-ray mission capable of spatial, non-dispersive high resolution spectroscopy covering at least the soft x-ray band over a large field of view. in this white paper, we demonstrate how the line emission mapper (lem) probe mission concept will revolutionize our current picture of the icm enrichment. specifically, we show that lem will be able to (i) spatially map the distribution of ten key chemical elements out to the virial radius of a nearby relaxed cluster and (ii) measure metal abundances in serendipitously discovered high-redshift protoclusters. altogether, these key observables will allow us to constrain the chemical history of the largest gravitationally bound structures of the universe. they will also solve key questions such as the universality of the initial mass function (imf) and the initial metallicity of the stellar populations producing these metals, as well as the relative contribution of asymptotic giant branch (agb) stars, core-collapse, and type ia supernovae to enrich the cosmic web over mpc scales. concrete observing strategies are also briefly discussed. | exploring chemical enrichment of the intracluster medium with the line emission mapper |
we present simulations of the multiphase interstellar medium (ism) at solar neighbourhood conditions including thermal and non-thermal ism processes, star cluster formation, and feedback from massive stars: stellar winds, hydrogen ionizing radiation computed with the novel treeray radiative transfer method, supernovae (sn), and the injection of cosmic rays (cr). n-body dynamics is computed with a 4th-order hermite integrator. we systematically investigate the impact of stellar feedback on the self-gravitating ism with magnetic fields, cr advection and diffusion, and non-equilibrium chemical evolution. sn-only feedback results in strongly clustered star formation with very high star cluster masses, a bi-modal distribution of the ambient sn densities, and low volume-filling factors (vff) of warm gas, typically inconsistent with local conditions. early radiative feedback prevents an initial starburst, reduces star cluster masses and outflow rates. furthermore, star formation rate surface densities of $\sigma _{\dot{m}_\star } = 1.4-5.9 \times 10^{-3}$$\mathrm{m}_\odot \, \mathrm{yr}^{-1}\, \mathrm{kpc}^{-2}$, vffwarm = 60-80 per cent as well as thermal, kinetic, magnetic, and cosmic ray energy densities of the model including all feedback mechanisms agree well with observational constraints. on the short, 100 myr, time-scales investigated here, crs only have a moderate impact on star formation and the multiphase gas structure and result in cooler outflows, if present. our models indicate that at low gas surface densities sn-only feedback only captures some characteristics of the star-forming ism and outflows/inflows relevant for regulating star formation. instead, star formation is regulated on star cluster scales by radiation and winds from massive stars in clusters, whose peak masses agree with solar neighbourhood estimates. | silcc vi - multiphase ism structure, stellar clustering, and outflows with supernovae, stellar winds, ionizing radiation, and cosmic rays |
we further investigate the dark energy model based on the finsler geometry inspired osculating barthel-kropina cosmology. the barthel-kropina cosmological approach is based on the introduction of a barthel connection in an osculating finsler geometry, with the connection having the property that it is the levi-civita connection of a riemannian metric. from the generalized friedmann equations of the barthel-kropina model, obtained by assuming that the background riemannian metric is of the friedmann-lemaitre-robertson-walker type, an effective geometric dark energy component can be generated, with the effective, geometric type pressure, satisfying a linear barotropic type equation of state. the cosmological tests, and comparisons with observational data of this dark energy model are considered in detail. to constrain the barthel-kropina model parameters, and the parameter of the equation of state, we use 57 hubble data points, and the pantheon supernovae type ia data sample. the st statistical analysis is performed by using markov chain monte carlo (mcmc) simulations. a detailed comparison with the standard λ cdm model is also performed, with the akaike information criterion (aic), and the bayesian information criterion (bic) used as the two model selection tools. the statefinder diagnostics consisting of jerk and snap parameters, and the om(z) diagnostics are also considered for the comparative study of the barthel-kropina and λ cdm cosmologies. our results indicate that the barthel-kropina dark energy model gives a good description of the observational data, and thus it can be considered a viable alternative of the λ cdm model. | cosmological tests of the osculating barthel-kropina dark energy model |
we describe the dark energy survey (des) deep fields, a set of images and associated multiwavelength catalogue (ugrizjhks) built from dark energy camera (decam) and visible and infrared survey telescope for astronomy (vista) data. the des deep fields comprise 11 fields (10 des supernova fields plus cosmos), with a total area of ~30 sq. deg. in ugriz bands and reaching a maximum i-band depth of 26.75 (ab, 10σ, 2 arcsec). we present a catalogue for the des 3-yr cosmology analysis of those four fields with full 8-band coverage, totalling 5.88 sq. deg. after masking. numbering 2.8 million objects (1.6 million post-masking), our catalogue is drawn from images coadded to consistent depths of r = 25.7, i = 25, and z = 24.3 mag. we use a new model-fitting code, built upon established methods, to deblend sources and ensure consistent colours across the u-band to ks-band wavelength range. we further detail the tight control we maintain over the point-spread function modelling required for the model fitting, astrometry and consistency of photometry between the four fields. the catalogue allows us to perform a careful star-galaxy separation and produces excellent photometric redshift performance (nmad = 0.023 at i < 23). the deep-fields catalogue will be made available as part of the cosmology data products release, following the completion of the des 3-yr weak lensing and galaxy clustering cosmology work. | dark energy survey year 3 results: deep field optical + near-infrared images and catalogue |
the tip of the red giant branch (trgb) provides a luminous standard candle for constructing distance ladders to measure the hubble constant. in practice, its measurements via edge-detection response (edr) are complicated by the apparent fuzziness of the tip and the multipeak landscape of the edr. previously, we optimized an unsupervised algorithm, comparative analysis of trgbs, to minimize the variance among multiple halo fields per host without relying on individualized choices, achieving state-of-the-art ~<0.05 mag distance measures for optimal data. here we apply this algorithm to an expanded sample of sn ia hosts to standardize these to multiple fields in the geometric anchor, ngc 4258. in concert with the pantheon+ sn ia sample, this analysis produces a (baseline) result of h 0 = 73.22 ± 2.06 km s-1 mpc-1. the largest difference in h 0 between this and similar studies employing the trgb derives from corrections for sn survey differences and local flows used in the most recent sn ia compilations that were absent in earlier studies. the sn-related differences total ~2.0 km s-1 mpc-1. a smaller share, ~1.4 km s-1 mpc-1, results from the inhomogeneity of the trgb calibration across the distance ladder. we employ a grid of 108 variants around the optimal trgb algorithm and find that the median of the variants is 72.94 ± 1.98 km s-1 mpc-1 with an additional uncertainty due to algorithm choices of 0.83 km s-1 mpc-1. none of these trgb variants result in an h 0 of less than 71.6 km s-1 mpc-1. | cats: the hubble constant from standardized trgb and type ia supernova measurements |
we present detailed optical photometry and spectroscopy of the type iin supernova (sn) 2021qqp. its unusual light curve is marked by a long gradual brightening (i.e., precursor) for about 300 days, a rapid increase in brightness for about 60 days, and then a sharp increase of about 1.6 mag in only a few days to a first peak of $m_r\approx -19.5$ mag. the light curve then turns over and declines rapidly, until it re-brightens to a second distinct and sharp peak with $m_r\approx -17.3$ mag centered at about 335 days after the first peak. the spectra are dominated by balmer-series lines with a complex morphology that includes a narrow component with a width of $\approx 1300$ km s$^{-1}$ (first peak) and $\approx 2500$ km s$^{-1}$ (second peak) that we associate with the circumstellar medium (csm), and a p cygni component with an absorption velocity of $\approx 8500$ km s$^{-1}$ (first peak) and $\approx 5600$ km s$^{-1}$ (second peak) that we associate with the sn-csm interaction shell. using the bolometric light curve and velocity evolution, we construct an analytical model to extract the csm profile and sn properties. we find two significant mass-loss episodes with peak mass loss rates of $\approx 10$ m$_\odot$ yr$^{-1}$ and $\approx 5$ m$_\odot$ yr$^{-1}$ about 0.8 and 2 years before explosion, and a total csm mass of $\approx 2-4\,m_\odot$. we show that the most recent mass-loss episode can explain the precursor for the year preceding the explosion. the sn ejecta mass is constrained to be $m_{\rm sn}\approx 5-30\,m_\odot$ for an explosion energy of $e_{\rm sn}\approx (3-10)\times10^{51}\,{\rm erg}$. we discuss eruptive massive stars (luminous blue variable, pulsational pair instability) and an extreme stellar merger with a compact object as possible progenitor channels for generating the energetic explosion in the complex csm environment. | multiple peaks and a long precursor in the type iin supernova 2021qqp: an energetic explosion in a complex circumsteller environment |
we identify the progenitor star of sn 2023ixf in the nearby galaxy messier 101 using keck/nirc2 adaptive optics imaging and pre-explosion hst/acs images. the supernova position, localized with diffraction-spike pattern and high precision relative astrometry, unambiguously coincides with a single progenitor candidate of m_f814w=24.96(-0.04)(+0.05). forced photometry further recovers 2-sigma detections in the f673n and f675w bands and imposes robust flux limits on the bluer bands. given the reported infrared excess and semi-regular variability of the progenitor, we fit a time-dependent spectral energy distribution (sed) model of a dusty red supergiant (rsg) to a combined dataset of hst photometry, as well as ground-based near-infrared and spitzer/irac [3.6], [4.5] photometry from the literature. the progenitor closely resembles a rsg of t_eff=3343+/-27 k and logl=5.10+/-0.02, with a 0.11+/-0.01 dex (25.2+/-1.7 per cent) variation over the mean luminosity at a period of p=1128.3+/-6.5 days, heavily obscured by a dust envelope with an optical depth of tau=2.83+/-0.03 at 1 micron (or a_v=10.28+/-0.11 mag). such observed signatures match a post-main sequence star of 18.1(-1.2)(+0.7) msun, close to the most massive sn ii progenitor, with a pulsation-enhanced mass-loss rate of m_dot=(3.58+/-0.15) x 10^(-4) msun/yr. the dense and confined circumstellar material is likely ejected during the last episode of radial pulsation before the explosion. notably, we find strong evidence for periodic variation of tau (or both t_eff and tau) along with luminosity, a necessary assumption to reproduce the wavelength dependence of the variability, which implies dust sublimation and condensation during radial pulsations. given the observed sed, partial dust obscuration remains a possible scenario, but any unobstructed binary companion over 7.1 msun can be ruled out. | the progenitor star of sn 2023ixf: a massive red supergiant with enhanced, episodic pre-supernova mass loss |
neutrinos play pivotal roles in determining fluid dynamics, nucleosynthesis, and their observables in core-collapse supernova (ccsn) and binary neutron star merger (bnsm). in this letter, we present a novel phenomenon, collisional flavor swap, in which neutrino-matter interactions trigger the complete interchange of neutrino spectra between two different flavors, aided by neutrino self-interactions. we find a necessary condition to trigger the collisional swap is occurrences of resonance-like collisional flavor instability. after the collisional swap, spectral-swap like features emerge in neutrino spectra. since flavor swaps correspond to the most extreme case in flavor conversions, they have a great potential to affect ccsn and bnsm phenomena. | collisional flavor swap with neutrino self-interactions |
we present 1.3 mm (230 ghz) observations of the recent and nearby type ii supernova, sn 2023ixf, obtained with the submillimeter array (sma) at 2.6-18.6 days after explosion. the observations were obtained as part the sma large program, poets (pursuit of extragalactic transients with the sma). we do not detect any emission at the location of sn 2023ixf, with the deepest limits of lν (230 ghz) ≲ 8.6 × 1025 erg s-1 hz-1 at 2.7 and 7.7 days, and lν (230 ghz) ≲ 3.4 × 1025 erg s-1 hz-1 at 18.6 days. these limits are about a factor of 2 times dimmer than the millimeter emission from sn 2011dh (iib), about 1 order of magnitude dimmer compared to sn 1993j (iib) and sn 2018ivc (iil), and about 30 times dimmer than the most luminous nonrelativistic sne in the millimeter band (type iib/ib/ic). using these limits in the context of analytical models that include synchrotron self-absorption and free-free absorption, we place constraints on the proximate circumstellar medium around the progenitor star, to a scale of ~2 × 1015 cm, excluding the range $\dot{m}\sim \mathrm{few}\times {10}^{-6}-{10}^{-2}$ m ⊙ yr-1 (for a wind velocity, vw= 115 km s-1, and ejecta velocity, v ej ~ (1 - 2) × 104 km s-1). these results are consistent with an inference of the mass-loss rate based on optical spectroscopy (~2 × 10-2 m ⊙ yr-1 for vw= 115 km s-1), but are in tension with the inference from hard x-rays (~7 × 10-4 m ⊙ yr-1 for vw= 115 km s-1). this tension may be alleviated by a nonhomogeneous and confined csm, consistent with results from high-resolution optical spectroscopy. | millimeter observations of the type ii sn 2023ixf: constraints on the proximate circumstellar medium |
recent observations have revealed massive galactic molecular outflows that may have the physical conditions (high gas densities) required to form stars. indeed, several recent models predict that such massive outflows may ignite star formation within the outflow itself. this star-formation mode, in which stars form with high radial velocities, could contribute to the morphological evolution of galaxies, to the evolution in size and velocity dispersion of the spheroidal component of galaxies, and would contribute to the population of high-velocity stars, which could even escape the galaxy. such star formation could provide in situ chemical enrichment of the circumgalactic and intergalactic medium (through supernova explosions of young stars on large orbits), and some models also predict it to contribute substantially to the star-formation rate observed in distant galaxies. although there exists observational evidence for star formation triggered by outflows or jets into their host galaxy, as a consequence of gas compression, evidence for star formation occurring within galactic outflows is still missing. here we report spectroscopic observations that unambiguously reveal star formation occurring in a galactic outflow at a redshift of 0.0448. the inferred star-formation rate in the outflow is larger than 15 solar masses per year. star formation may also be occurring in other galactic outflows, but may have been missed by previous observations owing to the lack of adequate diagnostics. | star formation inside a galactic outflow |
the origin of cosmic rays in our galaxy remains a subject of active debate. while supernova remnant (snr) shocks are often invoked as the sites of acceleration, it is now widely accepted that the difficulties of such sources in reaching pev energies are daunting and it seems likely that only a subclass of rare remnants can satisfy the necessary conditions. moreover, the spectra of cosmic rays escaping the remnants have a complex shape that is not obviously the same as the spectra observed at the earth. here, we investigate the process of particle acceleration at the termination shock that develops in the bubble excavated by star clusters' winds in the interstellar medium. while the main limitation to the maximum energy in snrs comes from the need for effective wave excitation upstream so as to confine particles in the near-shock region and speed up the acceleration process, at the termination shock of star clusters the confinement of particles upstream is guaranteed by the geometry of the problem. we develop a theory of diffusive shock acceleration at such shock and we find that the maximum energy may reach the pev region for powerful clusters in the high end of the luminosity tail for these sources. a crucial role in this problem is played by the dissipation of energy in the wind to magnetic perturbations. under reasonable conditions, the spectrum of the accelerated particles has a power-law shape with a slope 4/4.3, in agreement with what is required based upon standard models of cosmic ray transport in the galaxy. | particle acceleration in winds of star clusters |
the origin of heavy elements produced through rapid neutron capture (`r-process’) by seed nuclei is one of the current nucleosynthesis mysteries. core collapse supernovae (cc-sne; ref. ) and compact binary mergers are considered as possible sites. the first produces small amounts of material at a high event rate whereas the latter produces large amounts in rare events. radioactive elements with the right lifetime can break the degeneracy between high-rate/low-yield and low-rate/high-yield scenarios. among radioactive elements, most interesting is 244pu (half-life of 81 million years), for which both the current accumulation of live 244pu particles accreted via interstellar particles in the earth’s deep-sea floor and the early solar system (ess) abundances have been measured. interestingly, the estimated 244pu abundance in the current interstellar medium inferred from deep-sea measurements is significantly lower than that corresponding to the ess measurements. here we show that both the current and ess abundances of 244pu are naturally explained within the low-rate/high-yield scenario. the inferred event rate remarkably agrees with compact binary merger rates estimated from galactic neutron star binaries and from short gamma-ray bursts. furthermore, the ejected mass of r-process elements per event agrees with both theoretical and observational macronova/kilonova estimates. | short-lived 244pu points to compact binary mergers as sites for heavy r-process nucleosynthesis |
massive stars can explode in powerful supernovae (sne) forming neutron stars but they may also collapse directly into black holes (bhs). understanding and predicting their final fate is increasingly important, e.g, in the context of gravitational-wave astronomy. the interior mixing of stars in general and convective boundary mixing remain some of the largest uncertainties in their evolution. here, we investigate the influence of convective boundary mixing on the pre-sn structure and explosion properties of massive stars. using the 1d stellar evolution code mesa, we model single, non-rotating stars of solar metallicity with initial masses of $5-70\mathrm{m_\odot}$ and convective core step-overshooting of $0.05-0.50h_\mathrm{p}$. stars are evolved until the onset of iron core collapse, and the pre-sn models are exploded using a parametric, semi-analytic sn code. we use the compactness parameter to describe the interior structure of stars at core collapse. larger convective core overshooting shifts the location of the compactness peak by $1-2\mathrm{m_\odot}$ to higher $m_\mathrm{co}$. as the luminosity of the pre-sn progenitor is determined by $m_\mathrm{co}$, we predict bh formation for progenitors with luminosities $5.35<\log(l/\mathrm{l_\odot})<5.50$ and $\log(l/\mathrm{l_\odot})>5.80$. the luminosity range of bh formation agrees well with the observed luminosity of the red supergiant star n6946bh1 that disappeared without a bright sn and likely collapsed into a bh. while some of our models in the luminosity range $\log(l/\mathrm{l_\odot})=5.1-5.5$ indeed collapse to form bhs, this does not fully explain the lack of observed sn~iip progenitors at these luminosities, ie the missing red-supergiant problem. convective core overshooting affects the bh masses, the pre-sn location of stars in the hertzsprung-russell diagram, the plateau luminosity and duration of sn~iip lightcurves.[abridged] | convective-core overshooting and the final fate of massive stars |
we have simulated the collapse and evolution of the core of a solar-metallicity 40 m ⊙ star and find that it explodes vigorously by the neutrino mechanism, despite its very high "compactness." within ~1.5 s of explosion, a black hole forms. the explosion is very asymmetrical and has a total explosion energy of ~1.6 × 1051 erg. at black hole formation, its baryon mass is ~2.434 m ⊙ and gravitational mass is 2.286 m ⊙. seven seconds after black hole formation, an additional ~0.2 m ⊙ is accreted, leaving a black hole baryon mass of ~2.63 m ⊙. a disk forms around the proto-neutron star, from which a pair of neutrino-driven jets emanates. these jets accelerate some of the matter up to speeds of ~45,000 km s-1 and contain matter with entropies of ~50. the large spatial asymmetry in the explosion results in a residual black hole recoil speed of ~1000 km s-1. this novel black hole formation channel now joins the other black hole formation channel between ~12 and ~15 m ⊙ discovered previously and implies that the black hole/neutron star birth ratio for solar-metallicity stars could be ~20%. however, one channel leaves black holes in perhaps the ~5-15 m ⊙ range with low kick speeds, while the other leaves black holes in perhaps the ~2.5-3.0 m ⊙ mass range with high kick speeds. however, even ~8.8 s after core bounce the newly formed black hole is still accreting at a rate of ~2 × 10-2 m ⊙ s-1, and whether the black hole eventually achieves a significantly larger mass over time is yet to be determined. | black hole formation accompanied by the supernova explosion of a 40 m ⊙ progenitor star |
the spallation neutron source (sns) at oak ridge national laboratory provides an intense, high-quality source of neutrinos from pion decay at rest. this source was recently used for the first measurements of coherent elastic neutrino-nucleus scattering (cevns) by the coherent collaboration, which resulted in new constraints of physics beyond the standard model. the sns neutrino source will enable further cevns measurements, exploration of inelastic neutrino-nucleus interactions of particular relevance for understanding supernova neutrinos, and searches for accelerator-produced sub-gev dark matter. taking advantage of this unique facility, coherent's suite of detectors in neutrino alley at the sns is accumulating more data to address a broad physics program at the intersection of particle physics, nuclear physics, and astrophysics. this review describes coherent's first two cevns measurements, their interpretation, and the potential of a future physics program at the sns. | coherent at the spallation neutron source |
we present a comprehensive analysis of strong-lensing, weak-lensing shear and magnification data for a sample of 16 x-ray-regular and 4 high-magnification galaxy clusters at 0.19≲ z≲ 0.69 selected from cluster lensing and supernova survey with hubble (clash). our analysis combines constraints from 16-band hubble space telescope observations and wide-field multi-color imaging taken primarily with suprime-cam on the subaru telescope, spanning a wide range of cluster radii (10″-16‧). we reconstruct surface mass density profiles of individual clusters from a joint analysis of the full lensing constraints, and determine masses and concentrations for all of the clusters. we find the internal consistency of the ensemble mass calibration to be ≤5% ± 6% in the one-halo regime (200-2000 kpc h-1) compared to the clash weak-lensing-only measurements of umetsu et al. for the x-ray-selected subsample of 16 clusters, we examine the concentration-mass (c-m) relation and its intrinsic scatter using a bayesian regression approach. our model yields a mean concentration of c{| }z=0.34=3.95+/- 0.35 at m200c ≃ 14 × 1014 m⊙ and an intrinsic scatter of σ ({ln}{c}200{{c}})=0.13+/- 0.06, which is in excellent agreement with λ cold dark matter predictions when the clash selection function based on x-ray morphological regularity and the projection effects are taken into account. we also derive an ensemble-averaged surface mass density profile for the x-ray-selected subsample by stacking their individual profiles. the stacked lensing signal is detected at 33σ significance over the entire radial range ≤4000 kpc h-1, accounting for the effects of intrinsic profile variations and uncorrelated large-scale structure along the line of sight. the stacked mass profile is well described by a family of density profiles predicted for cuspy dark-matter-dominated halos in gravitational equilibrium, namely, the navarro-frenk-white (nfw), einasto, and darkexp models, whereas the single power-law, cored isothermal and burkert density profiles are disfavored by the data. we show that cuspy halo models that include the large-scale two-halo term provide improved agreement with the data. for the nfw halo model, we measure a mean concentration of {c}200{{c}}={3.79}-0.28+0.30 at {m}200{{c}}={14.1}-1.0+1.0× {10}14 {m}⊙ , demonstrating consistency between the complementary analysis methods. based in part on data collected at the subaru telescope, which is operated by the national astronomical society of japan. | clash: joint analysis of strong-lensing, weak-lensing shear, and magnification data for 20 galaxy clusters |
we present the results of a search for z = 9-10 galaxies within the first eight pointings of the hubble frontier fields (hff) survey and 20 cluster fields from the cluster lensing and supernova survey with hubble (clash) survey. combined with our previous analysis of the hubble ultra deep field, we have now completed a search for z = 9-10 galaxies over ≃ 130 arcmin2, spread across 29 hubble space telescope wide field camera 3/ir pointings. we confine our primary search for high-redshift candidates in this imaging to the uniformly deep, relatively low magnification regions (i.e. σ160 > 30 ab mag for hff and σ160 > 28.8 ab mag for clash in 0.5-arcsec apertures). we unveil a sample of 33 galaxy candidates at zphot ≥ 8.4, five of which have primary photometric redshift solutions in the range 9.6 < zphot < 11.2. the improved statistics and reduced cosmic variance provided by our new sample allows a more accurate determination of the ultraviolet (uv)-selected galaxy luminosity function (lf) at z ≃ 9. our new results strengthen our previous conclusion that the lf appears to evolve smoothly from z = 8 to 9, an evolution which can be equally well modelled by a factor of ≃ 2 drop in density, or a dimming of ≃ 0.5 mag in m⋆. moreover, we are able to place initial constraints on the z = 10 lf, finding that the number density at m1500 ≃ -19.7 is log (φ ) = -4.1^{+0.2}_{-0.3}, a factor of ≃ 2 lower than at z = 9. finally, we use our new results to revisit the issue of the decline in uv luminosity density (ρuv) at z ≥ 8. we conclude that the data continue to support a smooth decline in ρuv over the redshift interval 6 < z < 10, in agreement with simple models of early galaxy evolution driven by the growth in the underlying dark matter halo mass function. | the z = 9-10 galaxy population in the hubble frontier fields and clash surveys: the z = 9 luminosity function and further evidence for a smooth decline in ultraviolet luminosity density at z≥ 8 |
the cosmic merger rate density of black hole binaries (bhbs) can give us an essential clue to constraining the formation channels of bhbs, in light of current and forthcoming gravitational wave detections. following a monte carlo approach, we couple new population-synthesis models of bhbs with the illustris cosmological simulation, to study the cosmic history of bhb mergers. we explore six population-synthesis models, varying the prescriptions for supernovae, common envelope and natal kicks. in most considered models, the cosmic bhb merger rate follows the same trend as the cosmic star formation rate. the normalization of the cosmic bhb merger rate strongly depends on the treatment of common envelope and on the distribution of natal kicks. we find that most bhbs merging within ligo's instrumental horizon come from relatively metal-poor progenitors (<0.2 z⊙). the total masses of merging bhbs span a large range of values, from ∼6 to ∼82 m⊙. in our fiducial model, merging bhbs consistent with gw150914, gw151226 and gw170104 represent ∼6, 3 and 12 per cent of all bhbs merging within the ligo horizon, respectively. the heavy systems, like gw150914, come from metal-poor progenitors (<0.15 z⊙). most gw150914-like systems merging in the local universe appear to have formed at high redshift, with a long delay time. in contrast, gw151226-like systems form and merge all the way through the cosmic history, from progenitors with a broad range of metallicities. future detections will be crucial to put constraints on common envelope, on natal kicks, and on the bhb mass function. | the cosmic merger rate of stellar black hole binaries from the illustris simulation |
recently, constructing van der waals (vdw) heterojunctions by stacking different two-dimensional (2d) materials has been considered to be effective strategy to obtain the desired properties. here, through first-principles calculations, we find theoretically that the 2d n -inse/p -gese(sns) vdw heterojunctions are the direct-band-gap semiconductor with typical type-ii band alignment, facilitating the effective separation of photogenerated electron and hole pairs. moreover, they possess the high optical absorption strength (∼105 ), broad spectrum width, and excellent carrier mobility (∼103c m2v-1s-1 ). interestingly, under the influences of the interlayer coupling and external electric field, the characteristics of type-ii band alignment is robust, while the band-gap values and band offset are tunable. these results indicate that 2d n -inse/p -gese(sns) heterojunctions possess excellent optoelectronic and transport properties, and thus can become good candidates for next-generation optoelectronic nanodevices. | two-dimensional n -inse/p -gese(sns) van der waals heterojunctions: high carrier mobility and broadband performance |
double white dwarf (dwd) binaries are expected to be very common in the milky way, but their intrinsic faintness challenges the detection of these systems. currently, only a few tens of detached dwds are know. such systems offer the best chance of extracting the physical properties that would allow us to address a wealth of outstanding questions ranging from the nature of white dwarfs and thermonuclear supernovae, over stellar and binary evolution to mapping the galaxy. in this paper, we explore the prospects for detections of ultra-compact (with binary separations of a few solar radii or less) detached dwds in (1) optical radiation with gaia and the large synoptic survey telescope (lsst) and (2) gravitational wave radiation with large synoptic survey telescope (lisa). we show that gaia, lsst and lisa have the potential to detect, respectively, around a few hundred, a thousand and 25 thousand dwd systems. moreover, gaia and lsst data will extend by, respectively, a factor of 2 and 7 the guaranteed sample of lisa verification sources, binaries detectable in electromagnetic and gravitational wave radiation, opening the era of multimessenger astronomy for these sources. | prospects for detection of detached double white dwarf binaries with gaia, lsst and lisa |
we investigate whether the 4.4σ tension on h0 between sh0es 2019 and planck 2018 can be alleviated by a variation of newton's constant gn between the early and the late universe. this changes the expansion rate before recombination, similarly to the addition of δ neff extra relativistic degrees of freedom. we implement a varying gn in a scalar-tensor theory of gravity, with a non-minimal coupling of the form (m2+β phi2)r. if the scalar phi starts in the radiation era at an initial value phii ~ 0.5 mp and with β<0, a dynamical transition occurs naturally around the epoch of matter-radiation equality and the field evolves towards zero at late times. as a consequence, the h0 tension between sh0es (2019) and planck 2018+bao slightly decreases, as in δ neff models, to the 3.8σ level. we then perform a fit to a combined planck, bao and supernovae (sh0es and pantheon) dataset. when including local constraints on post-newtonian (pn) parameters, we find h0=69.08-0.71+0.6 km/s/mpc and a marginal improvement of δχ2simeq-3.2 compared to λcdm, at the cost of 2 extra parameters. in order to take into account scenarios where local constraints could be evaded, we also perform a fit without pn constraints and find h0=69.65-0.78+0.8 km/s/mpc and a more significant improvement δχ2=-5.4 with 2 extra parameters. for comparison, we find that the δ neff model gives h0=70.08-0.95+0.91 km/s/mpc and δχ2=-3.4 at the cost of one extra parameter, which disfavors the λcdm limit just above 2σ, since δ neff=0.34-0.16+0.15. overall, our varying gn model performs similarly to the δ neff model in respect to the h0 tension, if a physical mechanism to remove pn constraints can be implemented. | the h0 tension: δ gn vs. δ neff |
we present observations of asassn-19dj, a nearby tidal disruption event (tde) discovered in the post-starburst galaxy kug 0810+227 by the all-sky automated survey for supernovae (asas-sn) at a distance of d ≃ 98 mpc. we observed asassn-19dj from -21 to 392 d relative to peak ultraviolet (uv)/optical emission using high-cadence, multiwavelength spectroscopy and photometry. from the asas-sn g-band data, we determine that the tde began to brighten on 2019 february 6.8 and for the first 16 d the rise was consistent with a flux ∝t2 power law. asassn-19dj peaked in the uv/optical on 2019 march 6.5 (mjd = 58548.5) at a bolometric luminosity of l = (6.2 ± 0.2) × 1044 erg s-1. initially remaining roughly constant in x-rays and slowly fading in the uv/optical, the x-ray flux increased by over an order of magnitude ~225 d after peak, resulting from the expansion of the x-ray emitting region. the late-time x-ray emission is well fitted by a blackbody with an effective radius of ~1 × 1012 cm and a temperature of ~6 × 105 k. the x-ray hardness ratio becomes softer after brightening and then returns to a harder state as the x-rays fade. analysis of catalina real-time transient survey images reveals a nuclear outburst roughly 14.5 yr earlier with a smooth decline and a luminosity of lv ≥ 1.4 × 1043 erg s-1, although the nature of the flare is unknown. asassn-19dj occurred in the most extreme post-starburst galaxy yet to host a tde, with lick hδa = 7.67 ± 0.17 å. | discovery and follow-up of asassn-19dj: an x-ray and uv luminous tde in an extreme post-starburst galaxy |
neutron star mergers have been long considered as promising sites of heavy r-process nucleosynthesis. we overview the observational evidence supporting this scenario including: the total amount of r-process elements in the galaxy, extreme metal-poor stars, geological radioactive elemental abundances, dwarf galaxies and short gamma-ray bursts (sgrbs). recently, the advanced ligo and virgo observatories discovered a gravitational-wave signal of a neutron star merger, gw170817, as well as accompanying multi-wavelength electromagnetic (em) counterparts. the ultra-violet, optical and near infrared (n/r) observations point to r-process elements that have been synthesized in the merger ejecta. the rate and ejected mass inferred from gw170817 and the em counterparts are consistent with other observations. we however, find that, within the simple one zone chemical evolution models (based on merger rates with reasonable delay time distributions as expected from evolutionary models, or from observations of sgrbs), it is difficult to reconcile the current observations of the eu abundance history of galactic stars for [fe/h] ≳-1. this implies that to account for the role of mergers in the galactic chemical evolution, we need a galactic model with multiple populations that have different spatial distributions and/or varying formation rates. | neutron star mergers as sites of r-process nucleosynthesis and short gamma-ray bursts |
we use the physically consistent tilted spatially flat and untilted non-flat λcdm inflation models to constrain cosmological parameter values with the planck 2015 cosmic microwave background (cmb) anisotropy data and recent sne ia measurements, baryonic acoustic oscillations (bao) data, growth rate observations, and hubble parameter measurements. the most dramatic consequence of including the four non-cmb data sets is the significant strengthening of the evidence for non-flatness in the non-flat λcdm model, from 1.8σ for the cmb data alone to 5.1σ for the full data combination. the bao data is the most powerful of the non-cmb data sets in more tightly constraining model-parameter values and in favoring a spatially closed universe in which spatial curvature contributes about a percent to the current cosmological energy budget. the untilted non-flat λcdm model better fits the large-angle cmb temperature anisotropy angular spectrum and is more consistent with the dark energy survey constraints on the current value of the rms amplitude of mass fluctuations (σ 8) as a function of the current value of the nonrelativistic matter-density parameter (ω m ) but does not provide as good a fit to the smaller-angle cmb temperature anisotropy data, as does the tilted flat-λcdm model. some measured cosmological parameter values differ significantly between the two models, including the reionization optical depth and the baryonic matter density parameter, both of whose 2σ ranges (in the two models) are disjointed or almost so. | using the tilted flat-λcdm and the untilted non-flat λcdm inflation models to measure cosmological parameters from a compilation of observational data |
recent theoretical work indicates that the neutrino radiation in core-collapse supernovae may be susceptible to flavor instabilities that set in far behind the shock, grow extremely rapidly, and have the potential to profoundly affect supernova dynamics and composition. here we analyze the nonlinear collective oscillations that are prefigured by these instabilities. we demonstrate that a zero crossing in nνe-nν¯e as a function of propagation angle is not sufficient to generate instability. our analysis accounts for this fact and allows us to formulate complementary criteria. using fornax simulation data, we show that fast collective oscillations qualitatively depend on how forward peaked the neutrino angular distributions are. | neutrino oscillations in supernovae: angular moments and fast instabilities |
evolutionary models have shown the substantial effect that strong mass-loss rates ( $\dot{m}$ s) can have on the fate of massive stars. red supergiant (rsg) mass-loss is poorly understood theoretically, and so stellar models rely on purely empirical $\dot{m}$ -luminosity relations to calculate evolution. empirical prescriptions usually scale with luminosity and effective temperature, but $\dot{m}$ should also depend on the current mass and hence the surface gravity of the star, yielding more than one possible $\dot{m}$ for the same position on the hertzsprung-russell diagram. one can solve this degeneracy by measuring $\dot{m}$ for rsgs that reside in clusters, where age and initial mass (minit) are known. in this paper we derive $\dot{m}$ values and luminosities for rsgs in two clusters, ngc 2004 and rsgc1. using newly derived minit measurements, we combine the results with those of clusters with a range of ages and derive an minit-dependent $\dot{m}$ prescription. when comparing this new prescription to the treatment of mass-loss currently implemented in evolutionary models, we find models drastically overpredict the total mass-loss, by up to a factor of 20. importantly, the most massive rsgs experience the largest downward revision in their mass-loss rates, drastically changing the impact of wind mass-loss on their evolution. our results suggest that for most initial masses of rsg progenitors, quiescent mass-loss during the rsg phase is not effective at removing a significant fraction of the h-envelope prior to core-collapse, and we discuss the implications of this for stellar evolution and observations of sne and sn progenitors. | a new mass-loss rate prescription for red supergiants |
we investigate the thermal cosmology and terrestrial and astrophysical phenomenology of a sub-gev hadrophilic dark sector. the specific construction explored in this work features a dirac fermion dark matter candidate interacting with a light scalar mediator that dominantly couples to the up-quark. the correct freeze-out relic abundance may be achieved via dark matter annihilation directly to hadrons or through secluded annihilation to scalar mediators. a rich and distinctive phenomenology is present in this scenario, with probes arising from precision meson decays, proton beam dump experiments, colliders, direct detection experiments, supernovae, and nucleosynthesis. in the future, experiments such as na62, redtop, ship, sbnd, and news-g will be able to explore a significant portion of the cosmologically motivated parameter space. | probing light dark matter with a hadrophilic scalar mediator |
we analyze brans-dicke gravity with a cosmological constant, λ, and cold dark matter (bd-λcdm) in the light of the latest cosmological observations on distant supernovae, hubble rate measurements at different redshifts, baryonic acoustic oscillations, large-scale structure formation data, gravitational weak-lensing, and the cosmic microwave background under full planck 2015 cosmic microwave background likelihood. our analysis includes both the background and perturbations equations. we find that bd-λcdm is observationally favored as compared to the concordance λcdm model, which is traditionally defined within general relativity (gr). in particular, some well-known persisting tensions of the λcdm with the data, such as the excess in the mass fluctuation amplitude {σ }8 and especially the acute h 0-tension with the local measurements, essentially disappear in this context. furthermore, viewed from the gr standpoint, bd-λcdm cosmology mimics quintessence at ≳ 3σ c.l. near our time. | brans-dicke gravity with a cosmological constant smoothes out λcdm tensions |
realistic models of the galactic double white dwarf (dwd) population are crucial for testing and quantitatively defining the science objectives of the laser interferometer space antenna (lisa), a future european space agency's gravitational-wave observatory. in addition to numerous individually detectable dwds, lisa will also detect an unresolved confusion foreground produced by the underlying galactic population, which will affect the detectability of all lisa sources at frequencies below a few mhz. so far, the modelling of the dwd population for lisa has been based on binary population synthesis (bps) techniques. the aim of this study is to construct an observationally driven population. to achieve this, we employ a model developed by maoz, hallakoun & badenes for the statistical analysis of the local dwd population using two complementary large, multi-epoch, spectroscopic samples: the sloan digital sky survey, and the supernova ia progenitor survey. we calculate the number of lisa-detectable dwds and the galactic confusion foreground, based on their assumptions and results. we find that the observationally driven estimates yield (1) 2-5 times more individually detectable dwds than various bps forecasts, and (2) a significantly different shape of the dwd confusion foreground. both results have important implications for the lisa mission. a comparison between several variations to our underlying assumptions shows that our observationally driven model is robust, and that the uncertainty on the total number of lisa-detectable dwds is in the order of 20 per cent. | observationally driven galactic double white dwarf population for lisa |
we examine the scalings of galactic outflows with halo mass across a suite of 20 high-resolution cosmological zoom galaxy simulations covering halo masses in the range {10}9.5{--}{10}12 {m}⊙ . these simulations self-consistently generate outflows from the available supernova energy in a manner that successfully reproduces key galaxy observables, including the stellar mass-halo mass, tully-fisher, and mass-metallicity relations. we quantify the importance of ejective feedback to setting the stellar mass relative to the efficiency of gas accretion and star formation. ejective feedback is increasingly important as galaxy mass decreases; we find an effective mass loading factor that scales as {v}{{circ}}-2.2, with an amplitude and shape that are invariant with redshift. these scalings are consistent with analytic models for energy-driven wind, based solely on the halo potential. recycling is common: about half of the outflow mass across all galaxy masses is later reaccreted. the recycling timescale is typically ∼1 gyr, virtually independent of halo mass. recycled material is reaccreted farther out in the disk and with typically ∼2-3 times more angular momentum. these results elucidate and quantify how the baryon cycle plausibly regulates star formation and alters the angular momentum distribution of disk material across the halo mass range where most cosmic star formation occurs. | in-n-out: the gas cycle from dwarfs to spiral galaxies |
an excess of ∼10 - 20 gev cosmic-ray antiprotons has been identified in the spectrum reported by the ams-02 collaboration. the systematic uncertainties associated with this signal, however, have made it difficult to interpret these results. in this paper, we revisit the uncertainties associated with the time, charge and energy-dependent effects of solar modulation, the antiproton production cross section, and interstellar cosmic-ray propagation. after accounting for these uncertainties, we confirm the presence of a 4.7 σ antiproton excess, consistent with that arising from a mχ≈64 - 88 gev dark matter particle annihilating to b b ¯ with a cross section of σ v ≃(0.8 - 5.2 )×10-26 cm3/s . if we allow for the stochastic acceleration of secondary antiprotons in supernova remnants, the data continue to favor a similar range of dark matter models (mχ≈46 - 94 gev , σ v ≈(0.7 - 3.8 )×10-26 cm3/s ) with a significance of 3.3 σ . the same range of dark matter models that are favored to explain the antiproton excess can also accommodate the excess of gev-scale gamma rays observed from the galactic center. | a robust excess in the cosmic-ray antiproton spectrum: implications for annihilating dark matter |
we use the largest sample to date of spectroscopic supernova (sn) ia distances and redshifts to look for evidence in the hubble diagram of large-scale outflows caused by local voids suggested to exist at z < 0.15. our sample combines data from the pantheon sample with the foundation survey, and the most recent release of light curves from the carnegie supernova project, to create a sample of 1295 sne over a redshift range of 0.01 < z < 2.26. we make use of an inhomogeneous and isotropic lemaitre-tolman-bondi metric to model a void in the sn ia distance-redshift relation. we conclude that the sn luminosity distance-redshift relation is inconsistent at the 4-5σ confidence level with large local underdensities (| δ | > 20 % , where the density contrast δ = δρ/ρ) proposed in some galaxy count studies, and find no evidence of a change in the hubble constant corresponding to a void with a sharp edge in the redshift range 0.023 < z < 0.15. with an empirical precision of {σ }{h0}=0.60 % , we conclude that the distance ladder measurement is not affected by local density contrasts, in agreement with a cosmic variance of {σ }{h0}=0.42 % , predicted from simulations of large-scale structure. given that uncertainty in the distance ladder value is {σ }{h0}=2.2 % , this does not affect the hubble tension. we derive a 5σ constraint on local density contrasts on scales larger than 69 {mpc} {h}-1 of | δ | < 27 % . the presence of local structure does not appear to impede the possibility of measuring the hubble constant to 1% precision. | the local perspective on the hubble tension: local structure does not impact measurement of the hubble constant |
we report the discovery of a multiply imaged, gravitationally lensed type ia supernova, iptf16geu (sn 2016geu), at redshift z = 0.409. this phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. we used high-spatial-resolution observations to resolve four images of the lensed supernova, approximately 0.3 arc seconds from the center of the foreground galaxy. the observations probe a physical scale of ~1 kiloparsec, smaller than is typical in other studies of extragalactic gravitational lensing. the large magnification and symmetric image configuration imply close alignment between the lines of sight to the supernova and to the lens. the relative magnifications of the four images provide evidence for substructures in the lensing galaxy. | iptf16geu: a multiply imaged, gravitationally lensed type ia supernova |
red supergiants are the most common final evolutionary stage of stars that have initial masses between 8 and 35 times that of the sun1. during this stage, which lasts roughly 100,000 years1, red supergiants experience substantial mass loss. however, the mechanism for this mass loss is unknown2. mass loss may affect the evolutionary path, collapse and future supernova light curve3 of a red supergiant, and its ultimate fate as either a neutron star or a black hole4. from november 2019 to march 2020, betelgeuse—the second-closest red supergiant to earth (roughly 220 parsecs, or 724 light years, away)5,6—experienced a historic dimming of its visible brightness. usually having an apparent magnitude between 0.1 and 1.0, its visual brightness decreased to 1.614 ± 0.008 magnitudes around 7-13 february 20207—an event referred to as betelgeuse's great dimming. here we report high-angular-resolution observations showing that the southern hemisphere of betelgeuse was ten times darker than usual in the visible spectrum during its great dimming. observations and modelling support a scenario in which a dust clump formed recently in the vicinity of the star, owing to a local temperature decrease in a cool patch that appeared on the photosphere. the directly imaged brightness variations of betelgeuse evolved on a timescale of weeks. our findings suggest that a component of mass loss from red supergiants8 is inhomogeneous, linked to a very contrasted and rapidly changing photosphere. | a dusty veil shading betelgeuse during its great dimming |
we perform systematic investigation on the geometric, energetic, and electronic properties of group iv-vi binary monolayers (xy ), which are the counterparts of phosphorene, by employing density functional theory based electronic structure calculations. for this purpose, we choose the binary systems x y consisting of equal numbers of group iv (x = c, si, ge, sn) and group vi elements (y = o, s, se, te) in three geometrical configurations, the puckered, buckled and planar structures. the results of binding energy calculations show that all the binary systems studied are energetically stable. it is observed that, the puckered structure, similar to that of phosphorene, is the energetically most stable geometric configuration. moreover, the binding energies of buckled configuration are very close to those of the puckered configuration. our results of electronic band structure predict that puckered sio and cse are direct band semiconductors with gaps of 1.449 and 0.905 ev, respectively. band structure of cse closely resembles that of phosphorene. remaining group iv-vi binary monolayers in the puckered configuration and all the buckled monolayers are also semiconductors, but with indirect band gaps. importantly, we find that the difference between indirect and direct band gaps is very small for many puckered monolayers. thus there is a possibility of making these systems undergo transition from indirect to direct band gap semiconducting state by a suitable external influence. indeed, we show in the present work that seven binary monolayers, namely, sns, sise, gese, snse, site, gete, and snte become direct band gap semiconductors when they are subjected to a small mechanical strain (≤3 % ). this makes nine out of sixteen binary monolayers studied in the present work direct band gap semiconductors. thus there is a possibility of utilizing these binary counterparts of phosphorene in future light-emitting diodes and solar cells. | direct band gaps in group iv-vi monolayer materials: binary counterparts of phosphorene |
we explore three sets of cosmological hydrodynamical simulations, illustristng (tng50, tng100, and tng300), eagle, and simba, to investigate the physical processes impacting the distribution of baryons in and around haloes across an unprecedented mass range of $10^8\lt m_{\rm 200c}/\rm {{\rm m}_{\odot }}\lt 10^{15}$, from the halo centre out to scales as large as $30\, r_{\rm 200c}$. we demonstrate that baryonic feedback mechanisms significantly redistribute gas, lowering the baryon fractions inside haloes while simultaneously accumulating this material outside the virial radius. to understand this large-scale baryonic redistribution and identify the dominant physical processes responsible, we examine several variants of tng that selectively exclude stellar and active galactic nucleus (agn) feedback, cooling, and radiation. we find that heating from the uv background in low-mass haloes ($10^{8}\le {m_{\rm 200c}}/\rm {{\rm m}_{\odot }}\lt 10^{10}$), stellar feedback in intermediate-mass haloes ($10^{10}\le {m_{\rm 200c}}/\rm {{\rm m}_{\odot }}\lt 10^{12}$), and agn feedback in groups ($10^{12}\le {m_{\rm 200c}}/\rm {{\rm m}_{\odot }}\lt 10^{14}$) are the dominant processes. galaxy clusters ($m_{\rm 200c}/\rm {{\rm m}_{\odot }}\gt 10^{14}$) are the least influenced by these processes on large scales. we define a halo mass-dependent characteristic scale, the closure radius rc, within which all baryons associated with haloes are found. for groups and clusters, we introduce a universal relation between this scale and the halo baryon fraction: rc/r200c, 500c - 1 = β(z)(1 - fb(< r200c, 500c)/fb, cosmic), where $\beta (z)=\alpha \, (1+z)^\gamma$, and α and γ are free parameters fit using the simulations. accordingly, we predict that all baryons associated with observed x-ray haloes can be found within rc ~ 1.5-2.5r200c. our results can be used to constrain theoretical models, particularly the physics of supernova and agn feedback, as well as their interplay with environmental processes, through comparison with current and future x-ray and sunyaev-zel'dovich (sz) observations. | feedback reshapes the baryon distribution within haloes, in halo outskirts, and beyond: the closure radius from dwarfs to massive clusters |
coordination-related, 2d structural phase transitions are a fascinating facet of 2d materials with structural degeneracy. phosphorene and its new phases, exhibiting unique electronic properties, have received considerable attention. the 2d group iv-iv monochalcogenides (i.e. ges, gese, sns and snse) like black phosphorous possess puckered layered orthorhombic structure. the 2d group iv-iv monochalcogenides with advantages of earth-abundance, less toxicity, environmental compatibility and chemical stability, can be widely used in optoelectronics, piezoelectrics, photodetectors, sensors, li-batteries and thermoelectrics. in this review, we summarized recent research progress in theory and experiment, which studies the fundamental properties, applications and fabrication of 2d group iv-iv monochalcogenides and their new phases, and brings new perspectives and challenges for the future of this emerging field. | recent progress in 2d group iv-iv monochalcogenides: synthesis, properties and applications |
we present a novel set of stellar feedback models, implemented in the moving-mesh code arepo, designed for galaxy formation simulations with near-parsec (or better) resolution. these include explicit sampling of stars from the imf, allowing feedback to be linked to individual massive stars, an improved method for the modelling of h ii regions, photoelectric (pe) heating from a spatially varying fuv field and supernova feedback. we perform a suite of 32 simulations of isolated $m_\mathrm{vir} = 10^{10}\, \mathrm{m_\odot }$ galaxies with a baryonic mass resolution of $20\, \mathrm{m_\odot }$ in order to study the non-linear coupling of the different feedback channels. we find that photoionization (pi) and supernova feedback are both independently capable of regulating star formation to the same level, while pe heating is inefficient. pi produces a considerably smoother star formation history than supernovae. when all feedback channels are combined, the additional suppression of star formation rates is minor. however, outflow rates are substantially reduced relative to the supernova only simulations. we show that this is directly caused by a suppression of supernova clustering by the pi feedback, disrupting star-forming clouds prior to the first supernovae. we demonstrate that our results are robust to variations of our star formation prescription, feedback models and the baryon fraction of the galaxy. our results also imply that the burstiness of star formation and the mass loading of outflows may be overestimated if the adopted star particle mass is considerably larger than the mass of individual stars because this imposes a minimum cluster size. | efficient early stellar feedback can suppress galactic outflows by reducing supernova clustering |
gw190521 is a merger of two black holes (bhs), wherein at least one bh lies within the pair-instability (pi) mass gap, and it is difficult to form because of the effects of pi supernovae and pulsational pi (ppi). in this study, we examined the formation of gw190521-like bh-bhs under population (pop) iii environments by binary population synthesis calculations. we reveal that convective overshooting in stellar evolution strongly affects the formation of gw190521-like bh-bhs. a model with a small overshoot parameter (similar to genec) can form gw190521-like bh-bhs. the derived merger rate is 4 × 10-2 yr-1 gpc-3 at a redshift of ~0.82, which is comparable to the merger rate of gw190521-like bh-bhs inferred by gravitational wave (gw) observations. in this model, a ~90 m⊙ star collapses to form a ~90 m⊙ bh by avoiding ppi and pisn even if it is a member of a binary star. this is because it expands up to 102 r⊙, and lose only little mass through binary evolution. however, a model with a large overshoot parameter (similar to stern) cannot form gw190521-like bh-bhs at all. thus, we cannot conclude that a pop iii binary system is the origin of gw190521 because determination of the overshoot parameter involves highly uncertain. if a pop iii binary system is the origin of gw190521, the merger rate of bh-bhs including a 100-135 m⊙ bh is substantially smaller than that of gw190521-like bh-bhs. this will be assessed by gw observations in the near future. | population iii binary black holes: effects of convective overshooting on formation of gw190521 |
with myriads of detection events from a prospective galactic core-collapse supernova, current and future neutrino detectors will be able to sample detailed, time-dependent neutrino fluxes and spectra. this will offer significant possibilities of inferring supernova physics from the various phases of the neutrino signal, ranging from the neutronization burst through the accretion and early explosion phases to the cooling phase. the signal will constrain the time evolution of bulk parameters of the young proto-neutron star, such as its mass and radius, as well as the structure of the progenitor; probe multidimensional phenomena in the supernova core; and constrain the dynamics of the early explosion phase. aside from further astrophysical implications, supernova neutrinos may also shed light on the properties of matter at supranuclear densities and on open problems in particle physics. | neutrino emission as diagnostics of core-collapse supernovae |
the ligo/virgo gravitational-wave observatories have detected at least 50 double black hole (bh) coalescences. this sample is large enough to have allowed several recent studies to draw conclusions about the implied branching ratios between isolated binaries versus dense stellar clusters as the origin of double bhs. it has also led to the exciting suggestion that the population is highly likely to contain primordial bhs. here we demonstrate that such conclusions cannot yet be robust because of the large current uncertainties in several key aspects of binary stellar evolution. these include the development and survival of a common envelope, the mass and angular-momentum loss during binary interactions, mixing in stellar interiors, pair-instability mass loss, and supernova outbursts. using standard tools such as the rapid population synthesis codes startrack and compas and the detailed stellar evolution code mesa, we examine as a case study the possible future evolution of melnick 34, the most massive known binary star system (with initial component masses of 144 m ⊙ and 131 m ⊙). we show that, despite its fairly well-known orbital architecture, various assumptions regarding stellar and binary physics predict a wide variety of outcomes: from a close bh-bh binary (which would lead to a potentially detectable coalescence), through a wide bh-bh binary (which might be seen in microlensing observations), or a thorne-żytkow object, to a complete disruption of both objects by a pair-instability supernova. thus, because the future of massive binaries is inherently uncertain, sound predictions about the properties of bh-bh systems formed in the isolated binary evolution scenario are highly challenging at this time. consequently, it is premature to draw conclusions about the formation channel branching ratios that involve isolated binary evolution for the ligo/virgo bh-bh merger population. | the uncertain future of massive binaries obscures the origin of ligo/virgo sources |
we use 1169 pan-starrs supernovae (sne) and 195 low-z (z < 0.1) sne ia to measure cosmological parameters. though most pan-starrs sne lack spectroscopic classifications, in a previous paper we demonstrated that photometrically classified sne can be used to infer unbiased cosmological parameters by using a bayesian methodology that marginalizes over core-collapse (cc) sn contamination. our sample contains nearly twice as many sne as the largest previous sn ia compilation. combining sne with cosmic microwave background (cmb) constraints from planck, we measure the dark energy equation-of-state parameter w to be -0.989 ± 0.057 (stat+sys). if w evolves with redshift as w(a) = w 0 + wa (1 - a), we find w 0 = -0.912 ± 0.149 and wa= -0.513 ± 0.826. these results are consistent with cosmological parameters from the joint light-curve analysis and the pantheon sample. we try four different photometric classification priors for pan-starrs sne and two alternate ways of modeling cc sn contamination, finding that no variant gives a w differing by more than 2% from the baseline measurement. the systematic uncertainty on w due to marginalizing over cc sn contamination, {σ }wcc}=0.012, is the third-smallest source of systematic uncertainty in this work. we find limited (1.6σ) evidence for evolution of the sn color-luminosity relation with redshift, a possible systematic that could constitute a significant uncertainty in future high-z analyses. our data provide one of the best current constraints on w, demonstrating that samples with ∼5% cc sn contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a bayesian framework. | measuring dark energy properties with photometrically classified pan-starrs supernovae. ii. cosmological parameters |
we investigate the star formation-feedback cycle in cosmological galaxy formation simulations, focusing on the progenitors of milky way (mw)-sized galaxies. we find that in order to reproduce key properties of the mw progenitors, such as semi-empirically derived star formation histories (sfhs) and the shape of rotation curves, our implementation of star formation and stellar feedback requires (1) a combination of local early momentum feedback via radiation pressure and stellar winds, and subsequent efficient supernovae feedback, and (2) an efficacy of feedback that results in the self-regulation of the global star formation rate on kiloparsec scales. we show that such feedback-driven self-regulation is achieved globally for a local star formation efficiency per free fall time of {{ɛ }ff}≈ 10%. although this value is larger that the {{ɛ }ff}∼ 1% value usually inferred from the kennicutt-schmidt (ks) relation, we show that it is consistent with direct observational estimates of {{ɛ }ff} in molecular clouds. moreover, we show that simulations with local efficiency of {{ɛ }ff}≈ 10% reproduce the global observed ks relation. such simulations also reproduce the cosmic sfh of the mw-sized galaxies and satisfy a number of other observational constraints. conversely, we find that simulations that a priori assume an inefficient mode of star formation, instead of achieving it via stellar feedback regulation, fail to produce sufficiently vigorous outflows and do not reproduce observations. this illustrates the importance of understanding the complex interplay between star formation and feedback, and the detailed processes that contribute to the feedback-regulated formation of galaxies. | on the interplay between star formation and feedback in galaxy formation simulations |
we study the impact of stellar winds and supernovae on the multiphase interstellar medium using three-dimensional hydrodynamical simulations carried out with flash. the selected galactic disc region has a size of (500 pc)2 × ±5 kpc and a gas surface density of 10 m⊙ pc-2. the simulations include an external stellar potential and gas self-gravity, radiative cooling and diffuse heating, sink particles representing star clusters, stellar winds from these clusters that combine the winds from individual massive stars by following their evolution tracks, and subsequent supernova explosions. dust and gas (self-) shielding is followed to compute the chemical state of the gas with a chemical network. we find that stellar winds can regulate star (cluster) formation. since the winds suppress the accretion of fresh gas soon after the cluster has formed, they lead to clusters that have lower average masses (102-104.3 m⊙) and form on shorter time-scales (10-3-10 myr). in particular, we find an anticorrelation of cluster mass and accretion time-scale. without winds, the star clusters easily grow to larger masses for ∼5 myr until the first supernova explodes. overall, the most massive stars provide the most wind energy input, while objects beginning their evolution as b-type stars contribute most of the supernova energy input. a significant outflow from the disc (mass loading ≳1 at 1 kpc) can be launched by thermal gas pressure if more than 50 per cent of the volume near the disc mid-plane can be heated to t > 3 × 105 k. stellar winds alone cannot create a hot volume-filling phase. the models that are in best agreement with observed star formation rates drive either no outflows or weak outflows. | the silcc project - iii. regulation of star formation and outflows by stellar winds and supernovae |
gravitational transitions at low redshifts (zt<0.1 ) have been recently proposed as a solution to the hubble and growth tensions. such transitions would naturally lead to a transition in the absolute magnitude m of type ia supernovae (snia) at zt (late m transitions—l m t ) and possibly in the dark energy equation of state parameter w (late w -m transitions). here, we compare the quality of fit of this class of models to cosmological data, with the corresponding quality of fit of the cosmological constant model (λ cdm ) and some of the best smooth h (z ) deformation models [w cdm (cold dark matter), chevallier-polarski-linder, phenomenologically emergent dark energy]. we also perform model selection via the akaike information criterion (aic) and the bayes factor. we use the full cosmic microwave background temperature anisotropy spectrum data, the baryon acoustic oscillations data, the pantheon snia data, the snia absolute magnitude m as determined by cepheid calibrators and the value of the hubble constant h0 as determined by local snia calibrated using cepheids. we find that smooth h (z ) deformation models perform worse than transition models for the following reasons: (1) they have a worse fit to low-z geometric probes (baryon acoustic oscillations and snia data); (2) they favor values of the snia absolute magnitude m that are lower as compared to the value mc obtained with local cepheid calibrators at z <0.01 ; (3) they tend to worsen the ωm ,0-σ8 ,0 growth tension. we also find that the w -m transition model does not provide a better quality of fit to cosmological data than a pure m transition model (l m t ), where w is fixed to the λ cdm value w =-1 at all redshifts. we conclude that the l m t model has significant statistical advantages over smooth late-time h (z ) deformation models in addressing the hubble crisis. | late-transition versus smooth h (z )-deformation models for the resolution of the hubble crisis |
we investigate the impacts of the gravitational-wave (gw) standard siren observation of the einstein telescope (et) on constraining the total neutrino mass. we simulate 1000 gw events that would be observed by the et in its 10-year observation by taking the standard λcdm cosmology as a fiducial model. we combine the simulated gw data with other cosmological observations including cosmic microwave background (cmb), baryon acoustic oscillations (bao), and type ia supernovae (sn). we consider three mass hierarchy cases for the neutrino mass, i.e., normal hierarchy (nh), inverted hierarchy (ih), and degenerate hierarchy (dh). using planck+bao+sn, we obtain ∑mν < 0.175 ev for the nh case, ∑mν < 0.200 ev for the ih case, and ∑mν < 0.136 ev for the dh case. after considering the gw data, i.e., using planck+bao+sn+gw, the constraint results become ∑mν < 0.151 ev for the nh case, ∑mν < 0.185 ev for the ih case, and ∑mν < 0.122 ev for the dh case. we find that the gw data can help reduce the upper limits of ∑mν by 13.7%, 7.5%, and 10.3% for the nh, ih, and dh cases, respectively. in addition, we find that the gw data can also help break the degeneracies between ∑mν and other parameters. we show that the gw data of the et could greatly improve the constraint accuracies of cosmological parameters. | impacts of gravitational-wave standard siren observation of the einstein telescope on weighing neutrinos in cosmology |
we make the case that there can be no low-redshift solution to the h0 tension. to robustly answer this question, we use a very flexible parametrization for the dark energy equation of state such that every cosmological distance still allowed by data exists within this prior volume. to then answer whether there exists a satisfactory solution to the h0 tension within this comprehensive parametrization, we constrained the parametric form using different partitions of the planck cosmic microwave background, sdss-iv/eboss dr16 baryon acoustic oscillation, and pantheon supernova datasets. when constrained by just the cosmic microwave background dataset, there exists a set of equations of state which yields high h0 values, but these equations of state are ruled out by the combination of the supernova and baryon acoustic oscillation datasets. in other words, the constraint from the cosmic microwave background, baryon acoustic oscillation, and supernova datasets together does not allow for high h0 values and converges around an equation of state consistent with a cosmological constant. thus, since this very flexible parametrization does not offer a solution to the h0 tension, there can be no solution to the h0 tension that adds physics at only low redshifts. this is directly related to the expansion history of the universe and its geometrical properties and would include models beyond those parametrized by w (z ). | ruling out new physics at low redshift as a solution to the h0 tension |
gravitational waves (gws) from binary black hole (bbh) mergers provide a new probe of massive-star evolution and the formation channels of binary compact objects. by coupling the growing sample of bbh systems with population synthesis models, we can begin to constrain the parameters of such models and glean unprecedented knowledge about the inherent physical processes that underpin binary stellar evolution. in this study, we apply a hierarchical bayesian model to mass measurements from a synthetic gw sample to constrain the physical prescriptions in population models and the relative fraction of systems generated from various channels. we employ population models of two canonical formation scenarios in our analysis—isolated binary evolution involving a common-envelope phase and dynamical formation within globular clusters—with model variations for different black hole natal kick prescriptions. we show that solely with chirp mass measurements, it is possible to constrain natal kick prescriptions and the relative fraction of systems originating from each formation channel with { o }(100) of confident detections. this framework can be extended to include additional formation scenarios, model parameters, and measured properties of the compact binary. | constraining formation models of binary black holes with gravitational-wave observations |
improving the thermoelectric efficiency is one of the greatest challenges in materials science. the recent discovery of excellent thermoelectric performance in simple orthorhombic snse crystal offers new promise in this prospect [zhao et al. nature 508, 373 (2014)]. by calculating the thermoelectric properties of orthorhombic iv-vi compounds ges,gese,sns, and snse based on the first-principles combined with the boltzmann transport theory, we show that the seebeck coefficient, electrical conductivity, and thermal conductivity of orthorhombic snse are in agreement with the recent experiment. importantly, ges, gese, and sns exhibit comparative thermoelectric performance compared to snse. especially, the seebeck coefficients of ges, gese, and sns are even larger than that of snse under the studied carrier concentration and temperature region. we also use the cahill's model to estimate the lattice thermal conductivities at the room temperature. the large seebeck coefficients, high power factors, and low thermal conductivities make these four orthorhombic iv-vi compounds promising candidates for high-efficient thermoelectric materials. | high-efficient thermoelectric materials: the case of orthorhombic iv-vi compounds |
we introduce a new relativistic astrophysics code, spectre, that combines a discontinuous galerkin method with a task-based parallelism model. spectre's goal is to achieve more accurate solutions for challenging relativistic astrophysics problems such as core-collapse supernovae and binary neutron star mergers. the robustness of the discontinuous galerkin method allows for the use of high-resolution shock capturing methods in regions where (relativistic) shocks are found, while exploiting high-order accuracy in smooth regions. a task-based parallelism model allows efficient use of the largest supercomputers for problems with a heterogeneous workload over disparate spatial and temporal scales. we argue that the locality and algorithmic structure of discontinuous galerkin methods will exhibit good scalability within a task-based parallelism framework. we demonstrate the code on a wide variety of challenging benchmark problems in (non)-relativistic (magneto)-hydrodynamics. we demonstrate the code's scalability including its strong scaling on the ncsa blue waters supercomputer up to the machine's full capacity of 22 , 380 nodes using 671 , 400 threads. | spectre: a task-based discontinuous galerkin code for relativistic astrophysics |
this paper describes the design and implementation of our new multigroup, multidimensional radiation hydrodynamics code fornax and provides a suite of code tests to validate its application in a wide range of physical regimes. instead of focusing exclusively on tests of neutrino radiation hydrodynamics relevant to the core-collapse supernova problem for which fornax is primarily intended, we present here classical and rigorous demonstrations of code performance relevant to a broad range of multidimensional hydrodynamic and multigroup radiation hydrodynamic problems. our code solves the comoving-frame radiation moment equations using the m1 closure, utilizes conservative high-order reconstruction, employs semi-explicit matter and radiation transport via a high-order time stepping scheme, and is suitable for application to a wide range of astrophysical problems. to this end, we first describe the philosophy, algorithms, and methodologies of fornax and then perform numerous stringent code tests that collectively and vigorously exercise the code, demonstrate the excellent numerical fidelity with which it captures the many physical effects of radiation hydrodynamics, and show excellent strong scaling well above 100,000 mpi tasks. | fornax: a flexible code for multiphysics astrophysical simulations |
the superluminous supernova host galaxies survey aims to provide strong new constraints on the progenitors of superluminous supernovae (slsne) by understanding the relationship to their host galaxies. we present the photometric properties of 53 h-poor and 16 h-rich slsn host galaxies out to z ∼ 4. we model their spectral energy distributions to derive physical properties, which we compare with other galaxy populations. at low redshift, h-poor slsne are preferentially found in very blue, low-mass galaxies with high average specific star formation rates. as redshift increases, the host population follows the general evolution of star-forming galaxies towards more luminous galaxies. after accounting for secular evolution, we find evidence for differential evolution in galaxy mass, but not in the b band and the far-ultraviolet luminosity (3σ confidence). most remarkable is the scarcity of hosts with stellar masses above 1010 m⊙ for both classes of slsne. in case of h-poor slsne, we attribute this to a stifled production efficiency above ∼0.4 solar metallicity. however, we argue that, in addition to low metallicity, a short-lived stellar population is also required to regulate the slsn production. h-rich slsne are found in a very diverse population of star-forming galaxies. still, the scarcity of massive hosts suggests a stifled production efficiency above ∼0.8 solar metallicity. the large dispersion of the h-rich slsne host properties is in stark contrast to those of gamma-ray burst, regular core-collapse sn, and h-poor slsne host galaxies. we propose that multiple progenitor channels give rise to this subclass. | cosmic evolution and metal aversion in superluminous supernova host galaxies |
the electromagnetic observations of gw170817 were able to dramatically increase our understanding of neutron star mergers beyond what we learned from gravitational waves alone. these observations provided insight on all aspects of the merger from the nature of the gamma-ray burst to the characteristics of the ejected material. the ejecta of neutron star mergers are expected to produce such electromagnetic transients, called kilonovae or macronovae. characteristics of the ejecta include large velocity gradients, relative to supernovae, and the presence of heavy r-process elements, which pose significant challenges to the accurate calculation of radiative opacities and radiation transport. for example, these opacities include a dense forest of bound-bound features arising from near-neutral lanthanide and actinide elements. here we investigate the use of fine-structure, line-binned opacities that preserve the integral of the opacity over frequency. advantages of this area-preserving approach over the traditional expansion-opacity formalism include the ability to pre-calculate opacity tables that are independent of the type of hydrodynamic expansion and thus eliminate the computational expense of calculating opacities within radiation-transport simulations. tabular opacities are generated for all 14 lanthanides as well as a representative actinide element, uranium. we demonstrate that spectral simulations produced with the line-binned opacities agree well with results produced with the more accurate continuous monte carlo sobolev approach, as well as with the commonly used expansion-opacity formalism. the agreement between the line-binned and expansion-opacity results is explained as arising from the similarity in their opacities in the limit of low optical depth, where radiation transport is important in the ejecta. additional investigations illustrate the convergence of opacity with respect to the number of included lines, and elucidate sensitivities to different atomic physics approximations, such as fully and semirelativistic approaches. | a line-binned treatment of opacities for the spectra and light curves from neutron star mergers |
we present optical, near-infrared, and mid-infrared imaging of the host galaxy of frb 121102 with the gemini north telescope, the hubble space telescope, and the spitzer space telescope. the frb 121102 host galaxy is resolved, revealing a bright star-forming region located in the outskirts of the irregular, low-metallicity dwarf galaxy. the star-forming region has a half-light radius of 0.68 kpc (0\buildrel{\prime\prime}\over{.} 20), encompassing the projected location of the compact (< 0.7 pc), persistent radio source that is associated with frb 121102. the half-light diameter of the dwarf galaxy is 5-7 kpc, and broadband spectral energy distribution fitting indicates that it has a total stellar mass of {m}\star ∼ {10}8 {m}⊙ . the properties of the host galaxy of frb 121102 are comparable to those of extreme emission line galaxies, also known as hosts to some hydrogen-poor superluminous supernovae and long-duration γ-ray bursts. the projected location of frb 121102 within the star-forming region supports the proposed connection of frbs with newly born neutron stars or magnetars. | frb 121102 is coincident with a star-forming region in its host galaxy |
recent studies suggest spectroscopic differences explain a fraction of the variation in type ia supernova (sn ia) luminosities after light-curve/color standardization. in this work, (i) we empirically characterize the variations of standardized sn ia luminosities, and (ii) we use a spectroscopically inferred parameter, sip, to improve the precision of sne ia along the distance ladder and the determination of the hubble constant (h 0). first, we show that the pantheon+ covariance model modestly overestimates the uncertainty of standardized magnitudes by ~ 7%, in the parameter space used by the sh0es team to measure h 0; accounting for this alone yields h 0 = 73.01 ± 0.92 km s-1 mpc-1. furthermore, accounting for spectroscopic similarity between sne ia on the distance ladder reduces their relative scatter to ~ 0.12 mag per object (compared to ~ 0.14 mag previously). combining these two findings in the model of sn covariance, we find an overall 14% reduction (to ± 0.85 km s-1 mpc-1) of the uncertainty in the hubble constant and a modest increase in its value. including a budget for systematic uncertainties itemized by riess et al. (2022a), we report an updated local hubble constant with ~ 1.2% uncertainty, h 0 = 73.29 ± 0.90 km s-1 mpc-1. we conclude that spectroscopic differences among photometrically standardized sne ia do not explain the "hubble tension". rather, accounting for such differences increases its significance, as the discrepancy against λcdm calibrated by the planck 2018 measurement rises to 5.7σ. | leveraging sn ia spectroscopic similarity to improve the measurement of h 0 |
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