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we use the sphinx suite of high-resolution cosmological radiation hydrodynamics simulations to study how spatially and temporally inhomogeneous reionization impacts the baryonic content of dwarf galaxies and cosmic filaments. we compare simulations with and without stellar radiation to isolate the effects of radiation feedback from that of supernova, cosmic expansion, and numerical resolution. we find that the gas content of cosmic filaments can be reduced by more than 80 per cent following reionization. the gas inflow rates into haloes with ${m_{\rm vir}\lesssim 10^8\, \mathrm{m}_{\odot }}$ are strongly affected and are reduced by more than an order of magnitude compared to the simulation without reionization. a significant increase in gas outflow rates is found for halo masses ${m_{\rm vir}\lesssim 7\times 10^7\, \mathrm{m}_{\odot }}$. our simulations show that inflow suppression (i.e. starvation), rather than photoevaporation, is the dominant mechanism by which the baryonic content of high-redshift dwarf galaxies is regulated. at fixed redshift and halo mass, there is a large scatter in the halo baryon fractions that is entirely dictated by the timing of reionization in the local region surrounding a halo which can change by δz ≳ 3 at fixed mass. finally, although the gas content of high-redshift dwarf galaxies is significantly impacted by reionization, we find that most haloes with ${m_{\rm vir}\lesssim 10^8\, \mathrm{m}_{\odot }}$ can remain self-shielded and form stars long after reionization, until their local gas reservoir is depleted, suggesting that local group dwarf galaxies do not necessarily exhibit star formation histories that peak prior to z = 6. significantly larger simulation boxes will be required to capture the full process of reionization and understand how our results translate to environments not probed by our current work. | how to quench a dwarf galaxy: the impact of inhomogeneous reionization on dwarf galaxies and cosmic filaments |
we present the first simulations evolving resolved spectra of cosmic rays (crs) from mev-tev energies (including electrons, positrons, (anti)protons, and heavier nuclei), in live kinetic-magnetohydrodynamics galaxy simulations with star formation and feedback. we utilize new numerical methods including terms often neglected in historical models, comparing milky way analogues with phenomenological scattering coefficients ν to solar-neighbourhood [local interstellar medium (lism)] observations (spectra, b/c, e+/e-, $\mathrm{\bar{p}}/\mathrm{p}$, 10be/9be, ionization, and γ-rays). we show it is possible to reproduce observations with simple single-power-law injection and scattering coefficients (scaling with rigidity r), similar to previous (non-dynamical) calculations. we also find: (1) the circumgalactic medium in realistic galaxies necessarily imposes an $\sim 10\,$ kpc cr scattering halo, influencing the required ν(r). (2) increasing the normalization of ν(r) re-normalizes cr secondary spectra but also changes primary spectral slopes, owing to source distribution and loss effects. (3) diffusive/turbulent reacceleration is unimportant and generally sub-dominant to gyroresonant/streaming losses, which are sub-dominant to adiabatic/convective terms dominated by $\sim 0.1-1\,$ kpc turbulent/fountain motions. (4) cr spectra vary considerably across galaxies; certain features can arise from local structure rather than transport physics. (5) systematic variation in cr ionization rates between lism and molecular clouds (or galactic position) arises naturally without invoking alternative sources. (6) abundances of cno nuclei require most cr acceleration occurs around when reverse shocks form in sne, not in ob wind bubbles or later sedov-taylor stages of sne remnants. | first predicted cosmic ray spectra, primary-to-secondary ratios, and ionization rates from mhd galaxy formation simulations |
recent work has revealed that the light curves of hydrogen-poor (type i) superluminous supernovae (slsne), thought to be powered by magnetar central engines, do not always follow the smooth decline predicted by a simple magnetar spin-down model. here we present the first systematic study of the prevalence and properties of "bumps" in the post-peak light curves of 34 slsne. we find that the majority (44%-76%) of events cannot be explained by a smooth magnetar model alone. we do not find any difference in supernova properties between events with and without bumps. by fitting a simple gaussian model to the light-curve residuals, we characterize each bump with an amplitude, temperature, phase, and duration. we find that most bumps correspond with an increase in the photospheric temperature of the ejecta, although we do not see drastic changes in spectroscopic features during the bump. we also find a moderate correlation (ρ ≈ 0.5; p ≈ 0.01) between the phase of the bumps and the rise time, implying that such bumps tend to happen at a certain "evolutionary phase," (3.7 ± 1.4)t rise. most bumps are consistent with having diffused from a central source of variable luminosity, although sources further out in the ejecta are not excluded. with this evidence, we explore whether the cause of these bumps is intrinsic to the supernova (e.g., a variable central engine) or extrinsic (e.g., circumstellar interaction). both cases are plausible, requiring low-level variability in the magnetar input luminosity, small decreases in the ejecta opacity, or a thin circumstellar shell or disk. | bumpy declining light curves are common in hydrogen-poor superluminous supernovae |
we use the state-of-the-art data on cosmic chronometers (cch) and the pantheon+compilation of supernovae of type ia (snia) to test the constancy of the snia absolute magnitude, m, and the robustness of the cosmological principle (cp) at z ≲ 2 with a model-agnostic approach. we do so by reconstructing m(z) and the curvature parameter ωk(z) using gaussian processes. moreover, we use cch in combination with data on baryon acoustic oscillations (bao) from various galaxy surveys (6dfgs, boss, eboss, wigglez, des y3) to measure the sound horizon at the baryon-drag epoch, rd, from each bao data point and check their consistency. given the precision allowed by the cch, we find that m(z), ωk(z), and rd(z) are fully compatible (at $\lt 68$ per cent c.l.) with constant values. this justifies our final analyses, in which we put constraints on these constant parameters under the validity of the cp, the metric description of gravity and standard physics in the vicinity of the stellar objects, but otherwise in a model-independent way. if we exclude the snia contained in the host galaxies employed by sh0es, our results read $m=(-19.314^{+0.086}_{-0.108})$ mag, rd = (142.3 ± 5.3) mpc, and $\omega _k=-0.07^{+0.12}_{-0.15}$, with h0 = (71.5 ± 3.1) km s-1 mpc-1 (68 per cent c.l.). these values are independent of the main data sets involved in the h0 tension, namely, the cosmic microwave background and the first two rungs of the cosmic distance ladder. if, instead, we also consider the snia in the host galaxies, calibrated with cepheids, we measure $m=(-19.252^{+0.024}_{-0.036})$ mag, $r_\mathrm{ d}=(141.9^{+5.6}_{-4.9})$ mpc, $\omega _\mathrm{ k}=-0.10^{+0.12}_{-0.15}$, and $h_0=(74.0^{+0.9}_{-1.0})$ km s-1 mpc-1. | cosmic chronometers to calibrate the ladders and measure the curvature of the universe. a model-independent study |
stable mass transfer from a massive post-main sequence (post-ms) donor is thought to be a short-lived event of thermal-timescale mass transfer (∼10−3 m⊙ yr−1) which within ≲104 yr strips the donor star of nearly its entire h-rich envelope, producing a hot, compact helium star. this long-standing picture is based on stellar models with rapidly expanding hertzprung gap (hg) donor stars. motivated by a finding that in low-metallicity binaries, post-ms mass transfer may instead be initiated by donors already at the core-helium burning (cheb) stage, we used the mesa stellar-evolution code to compute grids of detailed massive binary models at three metallicities: those of the sun, the large magellanic cloud (lmc, zfe; lmc/zfe; ⊙ ≈ 0.36), and the small magellanic cloud (smc, zfe; smc/zfe; ⊙ ≈ 0.2). our grids span a wide range in orbital periods (∼3 to 5000 days) and initial primary masses (10 m⊙ to 36 − 53 m⊙, depending on metallicity). we find that metallicity strongly influences the course and outcome of mass-transfer evolution. we identify two novel types of post-ms mass transfer: (a) mass exchange on the long nuclear timescale (δtmt ≳ 105 yr, ṁ ∼ 10−5 m⊙ yr−1) that continues until the end of the cheb phase, and (b) rapid mass transfer leading to detached binaries with mass losers that are only partially stripped of their envelopes. at lmc and smc compositions, the majority of binary models with donor masses ≥17 m⊙ follow one of these two types of evolution. in neither (a) nor (b) does the donor become a fully stripped helium star by the end of cheb. boundaries between the different types of post-ms mass transfer evolution are associated with the degree of rapid post-ms expansion of massive stars and, for a given metallicity, are sensitive to the assumptions about internal mixing. at low metallicity, due to partial envelope stripping, we predict fewer hot fully stripped stars formed through binary interactions as well as higher compactness of the presupernova core structures of mass losers. nuclear-timescale post-ms mass transfer suggests a strong preference for metal-poor host galaxies of ultra-luminous x-ray sources with black-hole (bh) accretors and massive donors, some of which might be the immediate progenitors of binary bh mergers. it also implies a population of interacting binaries with blue and yellow supergiant donors. partially stripped stars could potentially explain the puzzling nitrogen-enriched slowly rotating (super)giants in the lmc. | partial-envelope stripping and nuclear-timescale mass transfer from evolved supergiants at low metallicity |
type ia supernovae (sne ia) are more precise standardizable candles when measured in the near-infrared (nir) than in the optical. with this motivation, from 2012 to 2017 we embarked on the raisin program with the hubble space telescope (hst) to obtain rest-frame nir light curves for a cosmologically distant sample of 37 sne ia (0.2 ≲ z ≲ 0.6) discovered by pan-starrs and the dark energy survey. by comparing higher-z hst data with 42 sne ia at z < 0.1 observed in the nir by the carnegie supernova project, we construct a hubble diagram from nir observations (with only time of maximum light and some selection cuts from optical photometry) to pursue a unique avenue to constrain the dark energy equation-of-state parameter, w. we analyze the dependence of the full set of hubble residuals on the sn ia host galaxy mass and find hubble residual steps of size ~0.06-0.1 mag with 1.5σ-2.5σ significance depending on the method and step location used. combining our nir sample with cosmic microwave background constraints, we find 1 + w = -0.17 ± 0.12 (statistical + systematic errors). the largest systematic errors are the redshift-dependent sn selection biases and the properties of the nir mass step. we also use these data to measure h 0 = 75.9 ± 2.2 km s-1 mpc-1 from stars with geometric distance calibration in the hosts of eight sne ia observed in the nir versus h 0 = 71.2 ± 3.8 km s-1 mpc-1 using an inverse distance ladder approach tied to planck. using optical data, we find 1 + w = -0.10 ± 0.09, and with optical and nir data combined, we find 1 + w = -0.06 ± 0.07; these shifts of up to ~0.11 in w could point to inconsistency in the optical versus nir sn models. there will be many opportunities to improve this nir measurement and better understand systematic uncertainties through larger low-z samples, new light-curve models, calibration improvements, and eventually by building high-z samples from the roman space telescope. | cosmological results from the raisin survey: using type ia supernovae in the near infrared as a novel path to measure the dark energy equation of state |
feedback from core collapse supernovae (sne), the final stage of evolution of massive stars, is a key element in galaxy formation theory. the energy budget of sn feedback, as well as the duration over which sne occur, are constrained by stellar lifetime models and the minimum mass star that ends its life as a sn. simplifying approximations for this sn rate are ubiquitous in simulation studies. we show here how the choice of sn budget and timings (t0 for the delay between star formation and the first sn, τsn for the duration of sn injection, and the minimum sn progenitor mass) drive changes in the regulation of star formation and outflow launching. extremely long delays for instantaneous injection of sn energy (t0 ≫ 20 myr) reduces star formation and drive stronger outflows compared smaller delays. this effect is primarily driven by enhanced clustering of young stars. with continuous injection of energy, longer sn durations results in a larger fraction of sn energy deposited in low ambient gas densities, where cooling losses are lower. this is effect is particularly when driven by the choice of the minimum sn progenitor mass, which also sets the total sn energy budget. these underlying uncertainties mean that despite advances in the sub-grid modeling of sn feedback, serious difficulties in constraining the strength of sn feedback remain. we recommend future simulations use realistic sn injection durations, and bound their results using sn energy budgets and durations for minimum sn progenitors of 7 and 9 m⊙. | uncertainties in supernova input rates drive qualitative differences in simulations of galaxy evolution |
the search for galactic pevatrons is now a well-identified key science project of all instruments operating in the very-high-energy domain. indeed, in this energy range, the detection of gamma rays clearly indicates that efficient particle acceleration is taking place, and observations can thus help identify which astrophysical sources can energize particles up to the ~pev range, thus being pevatrons. in the search for the origin of galactic cosmic rays (crs), the pev range is an important milestone, since the sources of galactic crs are expected to accelerate pev particles. this is how the central scientific goal that is 'solving the mystery of the origin of crs' has often been distorted into 'finding (a) pevatron(s)'. since supernova remnants (snrs) are often cited as the most likely candidates for the origin of crs, 'finding (a) pevatron(s)' has often become 'confirming that snrs are pevatrons'. pleasingly, the first detection(s) of pevatron(s) were not associated to snrs. moreover, all clearly detected snrs have yet revealed to not be pevatrons, and the detection from vhe gamma rays from regions unassociated with snrs, are reminding us that other astrophysical sites might well be pevatrons. this short review aims at highlighting a few important results on the search for galactic pevatrons. | the hunt for pevatrons: the case of supernova remnants |
the mismatch between the locally measured expansion rate of the universe and the one inferred from observations of the cosmic microwave background (cmb) assuming the canonical λcdm model has become the new cornerstone of modern cosmology, and many new-physics set ups are rising to the challenge. concomitant with the so-called h0 problem, there is evidence of a growing tension between the cmb-preferred value and the local determination of the weighted amplitude of matter fluctuations s8. it would be appealing and compelling if both the h0 and s8 tensions were resolved at once, but as yet none of the proposed new-physics models have done so to a satisfactory degree. herein, we adopt a systematic approach to investigate the possible interconnection among the free parameters in several classes of models that typify the main theoretical frameworks tackling the tensions on the universe expansion rate and the clustering of matter. our calculations are carried out using the publicly available boltzmann solver camb in combination with the sampler cosmomc. we show that even after combining the leading classes of models sampling modifications of both the early and late-time universe a simultaneous solution to the h0 and s8 tensions remains elusive. | dissecting the h0 and s8 tensions with planck + bao + supernova type ia in multi-parameter cosmologies |
we present direct n-body simulations, carried out with nbody6+ + gpu, of young and compact low-metallicity (z = 0.0002) star clusters with 1.1 × 105 stars, a velocity dispersion of ~15 $\mathrm{km\, s^{-1}}$, a half-mass radius rh = 0.6 pc, and a binary fraction of $10{{\ \rm per\,cent}}$ including updated evolution models for stellar winds and (pulsation) pair-instability supernovae (psne). within the first tens of megayears, each cluster hosts several black hole (bh) merger events which nearly cover the complete mass range of primary and secondary bh masses for current ligo-virgo-kagra gravitational wave detections. the importance of gravitational recoil is estimated statistically during post-processing analysis. we present possible formation paths of massive bhs above the assumed lower psn mass-gap limit ($45\, {\rm m}_\odot$) into the intermediate-mass black hole (imbh) regime ($\gt 100\, {\rm m}_\odot$) which include collisions of stars, bhs, and the direct collapse of stellar merger remnants with low core masses. the stellar evolution updates result in the early formation of heavier stellar bhs compared to the previous model. the resulting higher collision rates with massive stars support the rapid formation of massive bhs. for models assuming a high accretion efficiency for star-bh mergers, we present a first-generation formation scenario for gw190521-like events: a merger of two bhs which reached the psn mass-gap merging with massive stars. this event is independent of gravitational recoil and therefore conceivable in dense stellar systems with low escape velocities. one simulated cluster even forms an imbh binary (153, 173 m⊙) which is expected to merge within a hubble time. | black hole mergers in compact star clusters and massive black hole formation beyond the mass gap |
we investigate the effects of agn feedback on the cosmological evolution of an isolated elliptical galaxy by performing two-dimensional high-resolution hydrodynamical numerical simulations. the inner boundary of the simulation is chosen so that the bondi radius is resolved. compared to previous works, the two accretion modes—namely, hot and cold, which correspond to different accretion rates and have different radiation and wind outputs—are carefully discriminated, and the feedback effects by radiation and wind in each mode are taken into account. the most updated agn physics, including the descriptions of radiation and wind from the hot accretion flows and wind from cold accretion disks, are adopted. physical processes like star formation and sne ia and ii are taken into account. we study the agn light curve, typical agn lifetime, growth of the black hole mass, agn duty cycle, star formation, and x-ray surface brightness of the galaxy. we compare our simulation results with observations and find general consistency. comparisons with previous simulation works find significant differences, indicating the importance of agn physics. the respective roles of radiation and wind feedback are examined, and it is found that they are different for different problems of interest, such as agn luminosity and star formation. we find that it is hard to neglect any of them, so we suggest using the names “cold feedback mode” and “hot feedback mode” to replace the currently used ones. | active galactic nucleus feedback in an elliptical galaxy with the most updated agn physics. i. low angular momentum case |
with the advent of modern neutrino and gravitational wave (gw) detectors, the promise of multimessenger detections of the next galactic core-collapse supernova (ccsn) has become very real. such detections will give insight into the ccsn mechanism and the structure of the progenitor star, and may resolve longstanding questions in fundamental physics. in order to properly interpret these detections, a thorough understanding of the landscape of possible ccsn events, and their multimessenger signals, is needed. we present detailed predictions of neutrino and gw signals from 1d simulations of stellar core collapse, spanning the landscape of core-collapse progenitors from 9 to 120 m⊙. in order to achieve explosions in 1d, we use the supernova turbulence in reduced-dimensionality model, which includes the effects of turbulence and convection in 1d supernova simulations to mimic the 3d explosion mechanism. we study the gw emission from the 1d simulations using an astroseismology analysis of the protoneutron star. we find that the neutrino and gw signals are strongly correlated with the structure of the progenitor star and remnant compact object. using these correlations, future detections of the first few seconds of neutrino and gw emission from a galactic ccsn may be able to provide constraints on stellar evolution independent of preexplosion imaging and the mass of the compact object remnant prior to fallback accretion. | constraining properties of the next nearby core-collapse supernova with multimessenger signals |
we present high angular resolution (∼80 mas) alma continuum images of the sn 1987a system, together with co j = 2 \to 1, j = 6 \to 5, and sio j = 5 \to 4 to j = 7 \to 6 images, which clearly resolve the ejecta (dust continuum and molecules) and ring (synchrotron continuum) components. dust in the ejecta is asymmetric and clumpy, and overall the dust fills the spatial void seen in hα images, filling that region with material from heavier elements. the dust clumps generally fill the space where co j = 6 \to 5 is fainter, tentatively indicating that these dust clumps and co are locationally and chemically linked. in these regions, carbonaceous dust grains might have formed after dissociation of co. the dust grains would have cooled by radiation, and subsequent collisions of grains with gas would also cool the gas, suppressing the co j = 6 \to 5 intensity. the data show a dust peak spatially coincident with the molecular hole seen in previous alma co j = 2 \to 1 and sio j = 5 \to 4 images. that dust peak, combined with co and sio line spectra, suggests that the dust and gas could be at higher temperatures than the surrounding material, though higher density cannot be totally excluded. one of the possibilities is that a compact source provides additional heat at that location. fits to the far-infrared-millimeter spectral energy distribution give ejecta dust temperatures of 18-23 k. we revise the ejecta dust mass to m dust = 0.2-0.4 {m}⊙for carbon or silicate grains, or a maximum of <0.7 {m}⊙for a mixture of grain species, using the predicted nucleosynthesis yields as an upper limit. | high angular resolution alma images of dust and molecules in the sn 1987a ejecta |
it has been recently pointed out that neutrino fluxes from a supernova can show substantial flavor conversions almost immediately above the core. using linear stability analyses and numerical solutions of the fully nonlinear equations of motion, we perform a detailed study of these fast conversions, focussing on the region just above the supernova core. we carefully specify the instabilities for evolution in space or time, and find that neutrinos travelling towards the core make fast conversions more generic, i.e., possible for a wider range of flux ratios and angular asymmetries that produce a crossing between the zenith-angle spectra of νe and bar nue. using fluxes and angular distributions predicted by supernova simulations, we find that fast conversions can occur within tens of nanoseconds, only a few meters away from the putative neutrinospheres. if these fast flavor conversions indeed take place, they would have important implications for the supernova explosion mechanism and nucleosynthesis. | fast neutrino flavor conversions near the supernova core with realistic flavor-dependent angular distributions |
compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. the final stages in the formation of these systems have not been directly observed. we report the discovery of iptf 14gqr (sn 2014ft), a type ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.2 solar masses) and low kinetic energy (≈2 × 1050 ergs). early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. taken together, we interpret iptf 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems. | a hot and fast ultra-stripped supernova that likely formed a compact neutron star binary |
we report the results of analyses of galactic outflows in a sample of 45 low-redshift starburst galaxies in the cos legacy archive spectroscopic survey (classy), augmented by five additional similar starbursts with cosmic origins spectrograph (cos) data. the outflows are traced by blueshifted absorption lines of metals spanning a wide range of ionization potential. the high quality and broad spectral coverage of classy data enable us to disentangle the absorption due to the static interstellar medium (ism) from that due to outflows. we further use different line multiplets and doublets to determine the covering fraction, column density, and ionization state as a function of velocity for each outflow. we measure the outflow's mean velocity and velocity width, and find that both correlate in a highly significant way with the star formation rate, galaxy mass, and circular velocity over ranges of four orders of magnitude for the first two properties. we also estimate outflow rates of metals, mass, momentum, and kinetic energy. we find that, at most, only about 20% of silicon created and ejected by supernovae in the starburst is carried out in the warm phase we observe. the outflows' mass-loading factor increases steeply and inversely with both circular and outflow velocity (log-log slope ~-1.6), and reaches ~10 for dwarf galaxies. we find that the outflows typically carry about 10%-100% of the momentum injected by massive stars and about 1%-20% of the kinetic energy. we show that these results place interesting constraints on, and new insights into, models and simulations of galactic winds. *based on observations made with the nasa/esa hubble space telescope, obtained from the data archive at the space telescope science institute, which is operated by the association of universities for research in astronomy, inc., under nasa contract nas 5-26555. | classy iii. the properties of starburst-driven warm ionized outflows |
the milky way (mw) stellar halo contains relics of ancient mergers that tell the story of our galaxy's formation. some of them are identified due to their similarity in energy, actions, and chemistry, referred to as the "chemodynamical space," and are often attributed to distinct merger events. it is also known that our galaxy went through a significant merger event that shaped the local stellar halo during its first billion years. previous studies using n-body only and cosmological hydrodynamical simulations have shown that such a single massive merger can produce several "signatures" in the chemodynamical space, which can potentially be misinterpreted as distinct merger events. motivated by these, in this work we use a subset of the gastro library, which consists of several smoothed particle hydrodynamics+n-body models of a single accretion event in a mw-like galaxy. here, we study models with orbital properties similar to the main merger event of our galaxy and explore the implications to known stellar halo substructures. we find that (i) supernova feedback efficiency influences the satellite's structure and orbital evolution, resulting in distinct chemodynamical features for models with the same initial conditions; (ii) very retrograde high-energy stars are the most metal-poor of the accreted dwarf galaxy and could be misinterpreted as a distinct merger; (iii) the most bound stars are more metal-rich in our models, the opposite of what is observed in the mw, suggesting a secondary massive merger; and, finally, (iv) our models can reconcile other known apparently distinct substructures to a unique progenitor. | gastro library. i. the simulated chemodynamical properties of several gaia-sausage-enceladus-like stellar halos |
we present light curves and classification spectra of 17 hydrogen-poor superluminous supernovae (slsne) from the pan-starrs1 medium deep survey (ps1 mds). our sample contains all objects from the ps1 mds sample with spectroscopic classification that are similar to either of the prototypes sn 2005ap or sn 2007bi, without an explicit limit on luminosity. with a redshift range 0.3< z< 1.6, ps1 mds is the first slsn sample primarily probing the high-redshift population; our multifilter ps1 light curves probe the rest-frame uv emission, and hence the peak of the spectral energy distribution. we measure the temperature evolution and construct bolometric light curves, and find peak luminosities of (0.5{--}5)× {10}44 erg s-1 and lower limits on the total radiated energies of (0.3{--}2)× {10}51 erg. the light curve shapes are diverse, with both rise and decline times spanning a factor of ∼5 and several examples of double-peaked light curves. when correcting for the flux-limited nature of our survey, we find a median peak luminosity at 4000 å of {m}4000=-21.1 {mag} and a spread of σ =0.7 {mag}. | hydrogen-poor superluminous supernovae from the pan-starrs1 medium deep survey |
we present our analysis of the type ii supernova dlt16am (sn 2016ija). the object was discovered during the ongoing d< 40 {mpc} (dlt40) one-day cadence supernova search at r∼ 20.1 {mag} in the “edge-on” nearby (d=20.0+/- 4.0 {mpc}) galaxy ngc 1532. the subsequent prompt and high-cadenced spectroscopic and photometric follow-up revealed a highly extinguished transient, with e(b-v)=1.95+/- 0.15 {mag}, consistent with a standard extinction law with rv= 3.1 and a bright ({m}v=-18.48+/- 0.77 {mag}) absolute peak magnitude. a comparison of the photometric features with those of large samples of sne ii reveals a fast rise for the derived luminosity and a relatively short plateau phase, with a slope of {s}50v=0.84+/- 0.04 {mag}/50 {days}, consistent with the photometric properties typical of those of fast-declining sne ii. despite the large uncertainties on the distance and the extinction in the direction of dlt16am, the measured photospheric expansion velocity and the derived absolute v-band magnitude at ∼ 50 {days} after the explosion match the existing luminosity-velocity relation for sne ii. this paper includes data gathered with the 6.5 m magellan telescopes located at las campanas observatory, chile. | the early detection and follow-up of the highly obscured type ii supernova 2016ija/dlt16am |
we here propose a new model-independent technique to overcome the circularity problem affecting the use of gamma-ray bursts (grbs) as distance indicators through the use of ep-eiso correlation. we calibrate the ep-eiso correlation and find the grb distance moduli that can be used to constrain dark energy models. we use observational hubble data to approximate the cosmic evolution through bézier parametric curve obtained through the linear combination of bernstein basis polynomials. in doing so, we build up a new data set consisting of 193 grb distance moduli. we combine this sample with the supernova jla data set to test the standard λcdm model and its wcdm extension. we place observational constraints on the cosmological parameters through markov chain monte carlo numerical technique. moreover, we compare the theoretical scenarios by performing the akaike and deviance information statistical criteria.the 2σ level, while for the wcdm model we obtain ω _m=0.34^{+0.13}_{-0.15} and w=-0.86^{+0.36}_{-0.38} at the 2σ level. our analysis suggests that λcdm model is statistically favoured over the wcdm scenario. no evidence for extension of the λcdm model is found. | addressing the circularity problem in the ep-eiso correlation of gamma-ray bursts |
we investigate the star formation history (sfh) and chemical evolution of isolated analogs of local group (lg) ultrafaint dwarf galaxies (ufds; stellar mass range of {10}2 {m}⊙ < {m}* < {10}5 {m}⊙ ) and gas-rich, low-mass dwarfs (leo p analogs; stellar mass range of {10}5 {m}⊙ < {m}* < {10}6 {m}⊙ ). we perform a suite of cosmological hydrodynamic zoom-in simulations to follow their evolution from the era of the first generation of stars down to z = 0. we confirm that reionization, combined with supernova (sn) feedback, is primarily responsible for the truncated star formation in ufds. specifically, halos with a virial mass of {m}{vir}≲ 2× {10}9 {m}⊙form ≳ 90 % of stars prior to reionization. our work further demonstrates the importance of population iii stars, with their intrinsically high [{{c}}/{fe}] yields and the associated external metal enrichment, in producing low-metallicity stars ([{fe}/{{h}}]≲ -4) and carbon-enhanced metal-poor (cemp) stars. we find that ufds are composite systems, assembled from multiple progenitor halos, some of which hosted only population ii stars formed in environments externally enriched by sne in neighboring halos, naturally producing extremely low metallicity population ii stars. we illustrate how the simulated chemical enrichment may be used to constrain the sfhs of true observed ufds. we find that leo p analogs can form in halos with {m}{vir}∼ 4× {10}9 {m}⊙(z = 0). such systems are less affected by reionization and continue to form stars until z = 0, causing higher-metallicity tails. finally, we predict the existence of extremely low metallicity stars in lg ufd galaxies that preserve the pure chemical signatures of population iii nucleosynthesis. | connecting the first galaxies with ultrafaint dwarfs in the local group: chemical signatures of population iii stars |
we present a detailed mass reconstruction and a novel study on the substructure properties in the core of the cluster lensing and supernova survey with hubble (clash) and frontier fields galaxy cluster macs j0416.1-2403. we show and employ our extensive spectroscopic data set taken with the visible multi-object spectrograph instrument as part of our clash-vlt program, to confirm spectroscopically 10 strong lensing systems and to select a sample of 175 plausible cluster members to a limiting stellar mass of log (m */m ⊙) ~= 8.6. we reproduce the measured positions of a set of 30 multiple images with a remarkable median offset of only 0.''3 by means of a comprehensive strong lensing model comprised of two cluster dark-matter halos, represented by cored elliptical pseudo-isothermal mass distributions, and the cluster member components, parameterized with dual pseudo-isothermal total mass profiles. the latter have total mass-to-light ratios increasing with the galaxy hst/wfc3 near-ir (f160w) luminosities. the measurement of the total enclosed mass within the einstein radius is accurate to ~5%, including the systematic uncertainties estimated from six distinct mass models. we emphasize that the use of multiple-image systems with spectroscopic redshifts and knowledge of cluster membership based on extensive spectroscopic information is key to constructing robust high-resolution mass maps. we also produce magnification maps over the central area that is covered with hst observations. we investigate the galaxy contribution, both in terms of total and stellar mass, to the total mass budget of the cluster. when compared with the outcomes of cosmological n-body simulations, our results point to a lack of massive subhalos in the inner regions of simulated clusters with total masses similar to that of macs j0416.1-2403. our findings of the location and shape of the cluster dark-matter halo density profiles and on the cluster substructures provide intriguing tests of the assumed collisionless, cold nature of dark matter and of the role played by baryons in the process of structure formation. this work is based in large part on data collected at eso vlt (prog. id 186.a-0798) and nasa hst. | clash-vlt: insights on the mass substructures in the frontier fields cluster macs j0416.1-2403 through accurate strong lens modeling |
we use observational data from the pantheon supernovae sample, direct hubble constant measurements with cosmic chronometers, the cosmic microwave background shift parameter cmbshift , and redshift-space distortion (f σ8 ) measurements, in order to constrain f (t ) gravity. we do not follow the common γ parametrization within the semianalytical approximation of the growth rate, in order to avoid model-dependent uncertainties. to our knowledge this is the first time that f (t ) gravity has been analyzed within a bayesian framework, and with background and perturbation behaviour considered jointly. we show that all three examined f (t ) models are able to adequately describe the f σ8 data. furthermore, by applying the akaike, bayesian and deviance information criteria, we conclude that all considered models are statistically equivalent; however the most efficient candidate is the exponential model, which additionally presents a small deviation from the λ cdm paradigm. | bayesian analysis of f (t ) gravity using f σ8 data |
star clusters interact with the interstellar medium (ism) in various ways, most importantly in the destruction of molecular star-forming clouds, resulting in inefficient star formation on galactic scales. on cloud scales, ionizing radiation creates h ii regions, while stellar winds and supernovae (sne) drive the ism into thin shells. these shells are accelerated by the combined effect of winds, radiation pressure, and sn explosions, and slowed down by gravity. since radiative and mechanical feedback is highly interconnected, they must be taken into account in a self-consistent and combined manner, including the coupling of radiation and matter. we present a new semi-analytic 1d feedback model for isolated massive clouds (≥105 m⊙) to calculate shell dynamics and shell structure simultaneously. it allows us to scan a large range of physical parameters (gas density, star formation efficiency, and metallicity) and to estimate escape fractions of ionizing radiation fesc, i, the minimum star formation efficiency ɛmin required to drive an outflow, and recollapse time-scales for clouds that are not destroyed by feedback. our results show that there is no simple answer to the question of what dominates cloud dynamics, and that each feedback process significantly influences the efficiency of the others. we find that variations in natal cloud density can very easily explain differences between dense-bound and diffuse-open star clusters. we also predict, as a consequence of feedback, a 4-6 myr age difference for massive clusters with multiple generations. | winds and radiation in unison: a new semi-analytic feedback model for cloud dissolution |
we investigate the cosmological applications of fluids having an equation of state which is the analog to the one related to the isotropic deformation of crystalline solids, that is containing logarithmic terms of the energy density, allowing additionally for a bulk viscosity. we consider two classes of scenarios and we show that they are both capable of triggering the transition from deceleration to acceleration at late times. furthermore, we confront the scenarios with data from supernovae type ia (sn ia) and hubble function observations, showing that the agreement is excellent. moreover, we perform a dynamical system analysis and we show that there exist asymptotic accelerating attractors, arisen from the logarithmic terms as well as from the viscosity, which in most cases correspond to a phantom late-time evolution. finally, for some parameter regions we obtain a nearly de sitter late-time attractor, which is a significant capability of the scenario since the dark energy, although dynamical, stabilizes at the cosmological constant value. | cosmological fluids with logarithmic equation of state |
recent determination of the hubble constant via cepheid-calibrated supernovae by riess et al.find ∼3σ tension with inferences based on cosmic microwave background (cmb) temperature and polarization measurements from planck. this tension could be an indication of inadequacies in the concordance λcold dark matter model. here, we investigate the possibility that the discrepancy could instead be due to systematic bias or uncertainty in the cepheid calibration step of the distance ladder measurement by riess et al. we consider variations in total-to-selective extinction of cepheid flux as a function of line of sight, hidden structure in the period-luminosity relationship, and potentially different intrinsic colour distributions of cepheids as a function of host galaxy. considering all potential sources of error, our final determination of h0 = 73.3 ± 1.7 km s-1mpc-1 (not including systematic errors from the treatment of geometric distances or type ia supernovae) shows remarkable robustness and agreement with riess et al. we conclude systematics from the modelling of cepheid photometry, including cepheid selection criteria, cannot explain the observed tension between cepheid-variable and cmb-based inferences of the hubble constant. considering a `model-independent' approach to relating cepheids in galaxies with known distances to cepheids in galaxies hosting a type ia supernova and finding agreement with the riess et al. result, we conclude no generalization of the model relating anchor and host cepheid magnitude measurements can introduce significant bias in the h0 inference. | insensitivity of the distance ladder hubble constant determination to cepheid calibration modelling choices |
we present a full-fledged analysis of brans-dicke cosmology with a cosmological constant and cold dark matter (bd-λcdm for short). we extend the scenarios where the current cosmological value of the bd-field is restricted by the local astrophysical domain to scenarios where that value is fixed only by the cosmological observations, which should be more natural in view of the possible existence of local screening mechanism. our analysis includes both the background and perturbations equations in different gauges. we find that the bd-λcdm is favored by the overall cosmological data as compared to the concordance gr-λcdm model, namely data on distant supernovae, cosmic chronometers, local measurements of the hubble parameter, baryonic acoustic oscillations, large-scale structure formation and the cosmic microwave background under full planck 2018 cmb likelihood. we also test the impact of strong and weak-lensing data on our results, which can be significant. we find that the bd-λcdm can mimic effective quintessence with a significance of about 3.0-3.5σ c.l. (depending on the lensing datasets). the fact that the bd-λcdm behaves effectively as a running vacuum model (rvm) when viewed from the gr perspective helps to alleviate some of the existing tensions with the data, such as the σ8 excess predicted by gr-λcdm. on the other hand, the bd-λcdm model has a crucial bearing on the acute h0-tension with the local measurements, which is rendered virtually harmless owing to the small increase of the effective value of the gravitational constant with the expansion. the simultaneous alleviation of the two tensions is a most remarkable feature of bd-gravity with a cosmological constant in the light of the current observations, and hence goes in support of bd-λcdm against gr-λcdm. *dedicated to roberto d peccei. | brans-dicke cosmology with a λ-term: a possible solution to λcdm tensions |
a recent report has identified a central compact object (cco) within the supernova remnant hess j1731-347, with a mass and radius of $m=0.77^{+0.20}_{-0.17}m{\odot}$ and $r=10.4^{+0.86}_{-0.78}$ km, respectively. to investigate this light compact star, a density-dependent relativistic mean-field (ddrmf) model, specifically the ddvt model, has been employed. the ddvt model incorporates tensor couplings of vector mesons, which {can} successfully describe the properties of finite nuclei, such as charge radius, binding energy, and spin-orbit splitting. the introduction of tensor coupling reduces the influence of scalar mesons and generates a softer equation of state (eos) in the outer core of the neutron star. moreover, it has been found that the crust segment plays a crucial role in reproducing the mass-radius relation of hess j1731-347, indicating a preference for a soft crust eos. by manipulating the coupling strength of the isovector meson in the ddvt parameter set, a reasonable hadronic eos has been obtained, satisfying the constraints from the gravitational-wave signal gw170817, the simultaneous mass-radius measurements from the nicer collaboration, and the properties of finite nuclei. notably, the mass-radius relations derived from this hadronic eos also accurately describe the observables of hess j1731-347. therefore, based on our estimation, the cco in hess j1731-347 may represent the lightest known neutron star. | the hadronic equation of state of hess j1731-347 from the relativistic mean-field model with tensor coupling |
recent cosmological tensions, in particular, to infer the local value of the hubble constant $h_0$, have developed new independent techniques to constrain cosmological parameters in several cosmologies. moreover, even when the concordance cosmological constant cold dark matter ($\lambda$cdm) model has been well constrained with local observables, its physics has shown deviations from a flat background. therefore, to explore a possible deviation from a flat $\lambda$cdm model that could explain the $h_0$ value in tension with other techniques, in this paper we study new cosmological constraints in spatial curvature dark energy models. additionally, to standard current supernovae type ia (snia) catalogs, we extend the empirical distance ladder method through an snia sample using the capabilities of the james webb space telescope (jwst) to forecast snia up to $z \sim 6$, with information on the star formation rates at high redshift. furthermore, we found that our constraints provide an improvement in the statistics associated with $\omega_{m}$ when combining snia pantheon and snia pantheon+ catalogs with jw forecasting data. | constraining dark energy cosmologies with spatial curvature using supernovae jwst forecasting |
the physical collisions of two white dwarfs (wds) (i.e. not slow mergers) have been shown to produce type-ia-like supernovae (sne) explosions. most studies of wd-collisions have focused on zero impact-parameter (direct) collisions, which can also be studied in 2d. however, the vast majority of wd collisions arising from any evolutionary channels suggested to date, are expected to be indirect, i.e. have a non-negligible impact parameter upon collision. here we use the highest resolution 3d simulations to date (making use of the arepo code), in order to explore both direct and indirect collisions and the conditions in which they give rise to a detonation and the production of a luminous sne. using our simulations, we find a detonation criterion that can provide the critical impact parameter for an explosion to occur, depending on the density profile of the colliding wds, their composition, and their collision velocities. we find that the initial velocity has a significant impact on the amount of 56ni production from the explosion. furthermore, the 56ni production is also strongly dependent on the numerical resolution. while our results from the head-on collision with large initial velocities produce more 56ni than previous simulations, those with small and comparable velocities produce significantly less 56ni than previous works. | thermonuclear explosion criteria for direct and indirect collisions of co white dwarfs: a study of the impact-parameter threshold for detonation |
the flavor evolution of neutrinos in dense astrophysical sources, such as core-collapse supernovae or compact binary mergers, is non-linear due to the coherent forward scattering of neutrinos among themselves. recent work in this context has been addressed to figure out whether flavor equipartition could be a generic flavor outcome of fast flavor conversion. we investigate the flavor conversion physics injecting random perturbations in the neutrino field in two simulation setups: 1. a spherically symmetric simulation shell without periodic boundaries, with angular distributions evolving dynamically thanks to non-forward scatterings of neutrinos with the background medium, and neutrino advection; 2. a periodic simulation shell, with angular distributions of neutrinos defined a priori and neutrino advection. we find that, independent of the exact initial flavor configuration and type of perturbations, flavor equipartition is generally achieved in the system with periodic boundaries; in this case, perturbations aid the diffusion of flavor structures to smaller and smaller scales. however, flavor equipartition is not a general outcome in the simulation shell without periodic boundaries, where the inhomogeneities induced perturbing the neutrino field affect the flavor evolution, but do not facilitate the diffusion of flavor waves. this work highlights the importance of the choice of the simulation boundary conditions in the exploration of fast flavor conversion physics. | perturbing fast neutrino flavor conversion |
the latest improvements in the scale and calibration of type ia supernovae catalogues allow us to constrain the specific nature and evolution of dark energy through its effect on the expansion history of the universe. we present the results of bayesian cosmological model comparison on the sne~ia catalogue pantheon+, where flat $\lambda$cdm is preferred by the data over all other models and we find moderate evidence ($\delta \log \mathcal{z} \sim 2.5$) to reject a number of the alternate dark energy models. the effect of peculiar velocity corrections on model comparison is analysed, where we show that removing the peculiar velocity corrections results in a varying fit on non-$\lambda$cdm parameters. as well as comparing cosmological models, the bayesian methodology is extended to comparing the scatter model of the data, testing for non-gaussianity in the pantheon+ hubble residuals. we find that adding a scale parameter to the pantheon+ covariances, or alternately using a multivariate student's t-distribution fits the data better than the fiducial analysis, producing a cosmology independent evidence increase of $\delta \log \mathcal{z} = 2.29 $ and $2.46$ respectively. this improved treatment of the scatter decreases the uncertainty in the constraint on the hubble constant, finding $h_0 = 73.67 \pm 0.99 $ km s$^{-1}$ mpc$^{-1}$, in $ 5.7 \sigma$ tension with planck. we also explore $m_b$ transition models as a potential solution for the hubble tension, finding no evidence to support these models among the sne data. | non-gaussian likelihoods for type ia supernovae cosmology: implications for dark energy and $h_0$ |
self-consistent, time-dependent supernova (sn) simulations in three spatial dimensions (3d) are conducted with the aenus-alcar code, comparing, for the first time, calculations with fully multidimensional (fmd) neutrino transport and the ray-by-ray-plus (rbr+) approximation, both based on a two-moment solver with algebraic m1 closure. we find good agreement between 3d results with fmd and rbr+ transport for both tested grid resolutions in the cases of a 20 m ⊙ progenitor, which does not explode with the employed simplified set of neutrino opacities, and of an exploding 9 m ⊙ model. this is in stark contrast to corresponding axisymmetric (2d) simulations, which confirm previous claims that the rbr+ approximation can foster explosions in 2d, particularly in models with powerful axial sloshing of the stalled shock due to the standing accretion shock instability. however, while local and instantaneous variations of neutrino fluxes and heating rates can still be considerably higher with rbr+ transport in 3d, the time-averaged quantities are very similar to fmd results, because of the absence of a fixed, artificial symmetry axis that channels the flow. therefore, except for stochastic fluctuations, the neutrino signals and the postbounce evolution of 3d simulations with fmd and rbr+ transport are also very similar, particularly for our calculations with the better grid resolution. higher spatial resolution clearly has a more important impact than the differences due to the two transport treatments. our results back up the use of the rbr+ approximation for neutrino transport in 3d sn modeling. | three-dimensional core-collapse supernova simulations with multidimensional neutrino transport compared to the ray-by-ray-plus approximation |
the spt-3g 2018 tt/te/ee cosmic microwave background (cmb) data set (temperature and polarization) is used to place constraints on an axion-like model of early dark energy (ede). these data do not favor axion-like ede and place an upper limit on the maximum fraction of the total energy density $f_{\rm ede}< 0.172$ (at the 95% confidence level, cl). this is in contrast with act dr4 which gives $f_{\rm ede}=0.150^{+0.050}_{-0.078}$. when combining cmb measurements with measurements of the baryon acoustic oscillations and luminosity distance to type ia supernovae, we show that the tension with the s$h_0$es measurement of the hubble parameter goes up from 2.6$\sigma$ with planck to 2.9$\sigma$ with planck+spt-3g 2018. the additional inclusion of act dr4 data leads to a reduction of the tension to $1.6\sigma$, but the discrepancy between act dr4 and planck+spt-3g 2018 casts some doubt on the statistical consistency of this joint analysis. the importance of improved measurements of the cmb at both intermediate and small scales (in particular the shape of the damping tail) as well as the interplay between temperature and polarization measurements in constraining ede are discussed. upcoming ground-based measurements of the cmb will play a crucial role in determining whether ede remains a viable model to address the hubble tension. | current small-scale cmb constraints to axion-like early dark energy |
we present global fits of cosmologically stable axion-like particle and qcd axion models in the mass range 0.1 nev to 10 ev. we focus on the case where the peccei-quinn symmetry is broken before the end of inflation, such that the initial value of the axion field can be considered to be homogeneous throughout the visible universe. we include detailed likelihood functions from light-shining-through-wall experiments, haloscopes, helioscopes, the axion relic density, horizontal branch stars, supernova 1987a, white dwarf cooling, and gamma-ray observations. we carry out both frequentist and bayesian analyses, with and without the inclusion of white dwarf cooling. we explore the degree of fine-tuning present in different models and identify parameter regions where it is possible for qcd axion models to account for both the dark matter in the universe and the cooling hints, comparing them to specific dfsz- and ksvz-type models. we find the most credible parameter regions, allowing us to set (prior-dependent) upper and lower bounds on the axion mass. our analysis also suggests that qcd axions in this scenario most probably make up a non-negligible but sub-dominant component of the dark matter in the universe. | axion global fits with peccei-quinn symmetry breaking before inflation using gambit |
the origin of the solar system abundances of several proton-rich isotopes, especially $^{92,94}$mo and $^{96,98}$ru, has been an enduring mystery in nuclear astrophysics. an attractive proposal to solve this problem is the $\nu p$-process, which can operate in neutrino-driven outflows in a core-collapse supernova after the shock is launched. years of detailed studies, however, have cast doubt over the ability of this process to generate sufficiently high absolute and relative amounts of various $p$-nuclei. the $\nu p$-process is also thought to be excluded by arguments based on the long-lived radionuclide $^{92}$nb. here, we present explicit calculations, in which both the abundance ratios and the absolute yields of the $p$-nuclei up to $a\lesssim105$ are successfully reproduced, even when using the modern (medium enhanced) triple-$\alpha$ reaction rates. the process is also shown to produce the necessary amounts of $^{92}$nb. the models are characterized by subsonic outflows and by the protoneutron star masses in the {$\gtrsim1.7 m_\odot$ range}. this suggests that the mo and ru $p$-nuclides observed in the solar system were made in ccsn explosions characterized by an extended accretion stage. | successful $\\nu p$-process in neutrino-driven outflows in core-collapse supernovae |
multiwavelength observations have revealed that dense, confined circumstellar material (ccsm) commonly exists in the vicinity of supernova (sn) progenitors, suggesting enhanced mass losses years to centuries before their core collapse. interacting sne, which are powered or aided by interaction with the ccsm, are considered to be promising high-energy multimessenger transient sources. we present detailed results of broadband electromagnetic emission, following the time-dependent model proposed in the previous work on high-energy sn neutrinos [murase, phys. rev. d 97, 081301(r) (2018)]. we investigate electromagnetic cascades in the presence of coulomb losses, including inverse-compton and synchrotron components that significantly contribute to mev and high-frequency radio bands, respectively. we also discuss the application to sn 2023ixf. | interacting supernovae as high-energy multimessenger transients |
we report results from a series of three-dimensional (3d) rotational core-collapse simulations for 11.2 and 27 m⊙ stars employing neutrino transport scheme by the isotropic diffusion source approximation. by changing the initial strength of rotation systematically, we find a rotation-assisted explosion for the 27 m⊙ progenitor , which fails in the absence of rotation. the unique feature was not captured in previous two-dimensional (2d) self-consistent rotating models because the growing non-axisymmetric instabilities play a key role. in the rapidly rotating case, strong spiral flows generated by the so-called low t/|w| instability enhance the energy transport from the proto-neutron star (pns) to the gain region, which makes the shock expansion more energetic. the explosion occurs more strongly in the direction perpendicular to the rotational axis, which is different from previous 2d predictions. | three-dimensional simulations of rapidly rotating core-collapse supernovae: finding a neutrino-powered explosion aided by non-axisymmetric flows |
recent works have discovered a relatively tight correlation between $\omega_{\rm m}$ and properties of individual simulated galaxies. because of this, it has been shown that constraints on $\omega_{\rm m}$ can be placed using the properties of individual galaxies while accounting for uncertainties on astrophysical processes such as feedback from supernova and active galactic nuclei. in this work, we quantify whether using the properties of multiple galaxies simultaneously can tighten those constraints. for this, we train neural networks to perform likelihood-free inference on the value of two cosmological parameters ($\omega_{\rm m}$ and $\sigma_8$) and four astrophysical parameters using the properties of several galaxies from thousands of hydrodynamic simulations of the camels project. we find that using properties of more than one galaxy increases the precision of the $\omega_{\rm m}$ inference. furthermore, using multiple galaxies enables the inference of other parameters that were poorly constrained with one single galaxy. we show that the same subset of galaxy properties are responsible for the constraints on $\omega_{\rm m}$ from one and multiple galaxies. finally, we quantify the robustness of the model and find that without identifying the model range of validity, the model does not perform well when tested on galaxies from other galaxy formation models. | cosmology with multiple galaxies |
the next milky way supernova will be an epochal event in multi-messenger astronomy, critical to tests of supernovae, neutrinos, and new physics. realizing this potential depends on having realistic simulations of core collapse. we investigate the neutrino predictions of nearly all modern models (1-, 2-, and 3-d) over the first $\simeq$1 s, making the first detailed comparisons of these models to each other and to the sn 1987a neutrino data. even with different methods and inputs, the models generally agree with each other. however, even considering the low neutrino counts, the models generally disagree with data. what can cause this? we show that neither neutrino oscillations nor different progenitor masses appear to be a sufficient solution. we outline urgently needed work. | old data, new forensics: the first second of sn 1987a neutrino emission |
we study the coupling of hydrodynamics and reactions in simulations of the double detonation model for type ia supernovae. when assessing the convergence of simulations, the focus is usually on spatial resolution; however, the method of coupling the physics together as well as the tolerances used in integrating a reaction network also play an important role. in this paper, we explore how the choices made in both coupling and integrating the reaction portion of a simulation (operator / strang splitting vs.\ the simplified spectral deferred corrections method we introduced previously) influences the accuracy, efficiency, and the nucleosynthesis of simulations of double detonations. we find no need to limit reaction rates or reduce the simulation timestep to the reaction timescale. the entire simulation methodology used here is gpu-accelerated and made freely available as part of the castro simulation code. | sensitivity of simulations of double detonation type ia supernova to integration methodology |
we explore a possible explosion scenario resulting from core collapses of rotating massive stars that leave a black hole by performing radiation-viscous-hydrodynamics simulations in numerical relativity. we take moderately and rapidly rotating compact pre-collapse stellar models with zero-age main-sequence masses of 9m ⊙ and 20m ⊙ based on stellar evolution calculations as the initial conditions. we find that viscous heating in the disk formed around the central black hole is the power source for an outflow. the moderately rotating models predict a small ejecta mass of the order of 0.1m ⊙ and an explosion energy of ≲1051 erg. due to the small ejecta mass, these models may predict a short-timescale transient with a rise time of 3-5 days. this can lead to a bright (~1044 erg s-1) transient, like superluminous supernovae in the presence of a dense massive circumstellar medium. for hypothetically rapidly rotating models that have a high mass-infall rate onto the disk, the explosion energy is ≳3 × 1051 erg, which is comparable to or larger than that of typical stripped-envelope supernovae, indicating that a fraction of such supernovae may be explosions powered by black hole accretion disks. the explosion energy is still increasing at the end of the simulations with a rate of >1050 erg s-1, and thus, it may reach ~1052 erg. a nucleosynthesis calculation shows that the mass of 56ni amounts to ≳0.1m ⊙, which, together with the high explosion energy, may satisfy the required amount for broad-lined type ic supernovae. irrespective of the models, the lowest value of the electron fraction of the ejecta is ≳0.4; thus, synthesis of heavy r-process elements is not found in our models. | collapse of rotating massive stars leading to black hole formation and energetic supernovae |
cosmological observations in the new millennium have dramatically increased our understanding of the universe, but several fundamental questions remain unanswered. this topical group report describes the best opportunities to address these questions over the coming decades by extending observations to the $z<6$ universe. the greatest opportunity to revolutionize our understanding of cosmic acceleration both in the modern universe and the inflationary epoch would be provided by a new stage v spectroscopic facility (spec-s5) which would combine a large telescope aperture, wide field of view, and high multiplexing. such a facility could simultaneously provide a dense sample of galaxies at lower redshifts to provide robust measurements of the growth of structure at small scales, as well as a sample at redshifts $2<z<5$ to measure cosmic structure at the largest scales, spanning a sufficient volume to probe primordial non-gaussianity from inflation, to search for features in the inflationary power spectrum on a broad range of scales, to test dark energy models in poorly-explored regimes, and to determine the total neutrino mass and effective number of light relics. a number of compelling opportunities at smaller scales should also be pursued alongside spec-s5. the science collaborations analyzing desi and lsst data will need funding for a variety of activities, including cross-survey simulations and combined analyses. the results from these experiments can be greatly improved by smaller programs to obtain complementary data, including follow-up studies of supernovae and spectroscopy to improve photometric redshift measurements. the best future use of the vera c. rubin observatory should be evaluated later this decade after the first lsst analyses have been done. finally, investments in pathfinder projects could enable powerful new probes of cosmology to come online in future decades. | snowmass2021 cosmic frontier: report of the cf04 topical group on dark energy and cosmic acceleration in the modern universe |
we determine the hubble constant h0 precisely (2.3% uncertainty) in a manner independent of the cosmological model through gaussian process regression, using strong lensing and supernova data. strong gravitational lensing of a variable source can provide a time-delay distance dδt and angular diameter distance to the lens dd. these absolute distances can anchor type ia supernovae, which give an excellent constraint on the shape of the distance-redshift relation. updating our previous results to use the h0licow program's milestone data set consisting of six lenses, four of which have both dδt and dd measurements, we obtain ${h}_{0}={72.8}_{-1.7}^{+1.6}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{mpc}}^{-1}$ for a flat universe and ${h}_{0}={77.3}_{-3.0}^{+2.2}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{mpc}}^{-1}$ for a non-flat universe. we carry out several consistency checks on the data and find no statistically significant tensions, though a noticeable redshift dependence persists in a particular systematic manner that we investigate. speculating on the possibility that this trend of derived hubble constant with lens distance is physical, we show how this can arise through modified gravity light propagation, which would also impact the weak lensing σ8 tension. | determining model-independent h0 and consistency tests |
gravitational wave (gw) detections of binary black holes (bbhs) have shown evidence for a dearth of component black holes with masses above ∼50m⊙. this is consistent with expectations of a mass gap due to the existence of pair-instability supernovae (pisn). we argue that ground-based gw detectors will be sensitive to bbhs with masses above this gap, ≳120 m⊙. with no detections, 2 yr at upgraded sensitivity (a+) would constrain the local merger rate of these bbhs on the "far side" of the pisn gap to be lower than 0.01 yr-1gpc-3. alternatively, with a few tens of events we could constrain the location of the upper edge of the gap to the percent level. we consider the potential impact of "interloper" black holes within the pisn mass gap on this measurement. far side bbhs would also be observed by future instruments such as cosmic explorer (ce), einstein telescope (et) and lisa, and may dominate the fraction of multiband events. we show that by comparing observations from ground and space it is possible to constrain the merger rate history. moreover, we find that the upper edge of the pisn mass gap leaves an imprint on the spectral shape of the stochastic background of unresolved binaries, which may be accessible with a+ sensitivity. finally, we show that by exploiting the upper edge of the gap, these high-mass bbhs can be used as standard sirens to constrain the cosmic expansion at redshifts of ∼0.4, 0.8, and 1.5 with lisa, ligo-virgo, and ce/et, respectively. these far-side binaries would be the most massive bbhs ligo-virgo could detect. | jumping the gap: searching for ligo's biggest black holes |
context. the dominant site of production of r-process elements remains unclear despite recent observations of a neutron star merger. observational constraints on the properties of the sites can be obtained by comparing r-process abundances in different environments. the recent gaia data releases and large samples from high-resolution optical spectroscopic surveys are enabling us to compare r-process element abundances between stars formed in an accreted dwarf galaxy, gaia-enceladus, and those formed in the milky way.aims: our aim is to understand the origin of r-process elements in gaia-enceladus.methods: we first constructed a sample of stars so that our study on eu abundance is not affected by the detection limit. we then kinematically selected 76 gaia-enceladus stars and 81 in situ stars from the galactic archaeology with hermes (galah) dr3, of which 47 and 55 stars, respectively, can be used to study eu reliably.results: gaia-enceladus stars clearly show higher ratios of [eu/mg] than in situ stars. high [eu/mg] along with low [mg/fe] are also seen in relatively massive satellite galaxies such as the lmc, fornax, and sagittarius dwarfs. on the other hand, unlike these galaxies, gaia-enceladus does not show enhanced [ba/eu] or [la/eu] ratios suggesting a lack of significant s-process contribution. from comparisons with simple chemical evolution models, we show that the high [eu/mg] of gaia-enceladus can naturally be explained by considering r-process enrichment by neutron-star mergers with delay time distribution that follows a power-law similar to type ia supernovae but with a shorter minimum delay time. | r-process enhancements of gaia-enceladus in galah dr3 |
large uncertainties in the determinations of the equation of state of dense stellar matter allow the intriguing possibility that the bulk quark matter in beta equilibrium might be the true ground state of the matter at zero pressure. and quarks will form cooper pairs very readily since the dominant interaction between quarks is attractive in some channels. as a result, quark matter will generically exhibit color superconductivity, with the favored pairing pattern at intermediately high densities being two-flavor pairing. in the light of several possible candidates for such self-bound quark stars, including the very low-mass central compact object in supernova remnant hess j1731-347 reported recently, we carry out one field-theoretic model, the nambu-jona-lasinio model, of investigation on the stability of beta-stable two-flavor color superconducting (2sc) phase of quark matter, nevertheless find no physically-allowed parameter space for the existence of 2sc quark stars. | two-flavor color superconducting quark stars may not exist |
the main aim of this paper is to perform a model comparison for some reconstructions of the key properties that describe the dark energy of the universe i.e. energy density and the equation of state (eos). we carry out this process by using a binning and a linear interpolation methodologies, and on top of that, we incorporate a correlation function mechanism. an extension of the two of them was also introduced, where internal amplitudes are allowed to vary in height as well as in position. the reconstructions were made with data from the hubble parameter, supernovae type ia and baryon acoustic oscillations (h+sn+bao), all of which span a range from z =0.01 to z =2.34 . first we perform the parameter estimation for each of the reconstructions to then provide a model selection through the bayesian evidence. throughout our process we found a better fit to the data, up to 4 σ compared to λ cdm, and the presence of some interesting features, i.e. an oscillatory behaviour at late times, a decrease in the dark energy density component at early times and a transition to the phantom divide-line in the eos. to discern these features from noisy contributions, we include a principal component analysis and found that some of these characteristics should be taken into account to satisfy current observations. | model selection applied to reconstructions of the dark energy |
gravitational wave observations of binary black holes have revealed unexpected structure in the black hole mass distribution. previous studies of the mass distribution employ physically-motivated phenomenological models and infer the parameters that directly control the features of the mass distribution that are allowed in their model, associating the constraints on those parameters with their physical motivations. in this work, we take an alternative approach in which we introduce a model parameterizing the underlying stellar and core-collapse physics and obtaining the remnant black hole distribution as a derived byproduct. in doing so, we directly constrain the stellar physics necessary to explain the astrophysical distribution of black hole properties under a given model. we apply this approach to modeling the mapping between stellar core mass and remnant black hole mass, including the effects of mass loss due to the pulsational pair instability supernova (ppisn) process, which has been proposed as an explanation for the observed excess of black holes at $\sim 35 m_\odot$. placing constraints on the nuclear reaction rates necessary to explain the ppisn parameters, we conclude that the peak observed at $\sim 35 m_\odot$ is highly unlikely to be a signature from the ppisn process. this procedure can be applied to modeling any physical process that underlies the astrophysical mass distribution. allowing the parameters of the core-remnant mass relationship to evolve with redshift permits correlated and physically reasonable changes in the location, shape, and amplitude of features in the mass function. we find that the current data are consistent with no redshift evolution in the core-remnant mass relationship, but ultimately place only weak constraints on the change of these parameters. | physical models for the astrophysical population of black holes: application to the bump in the mass distribution of gravitational wave sources |
the elemental abundances between strontium and silver ($z = 38-47$) observed in the atmospheres of very metal-poor stars (vmp) in the galaxy may contain the fingerprint of the weak $r$-process and $\nu p$-process occurring in early core-collapse supernovae explosions. in this work, we combine various astrophysical conditions based on a steady-state model to cover the richness of the supernova ejecta in terms of entropy, expansion timescale, and electron fraction. the calculated abundances based on different combinations of conditions are compared with stellar observations with the aim of constraining supernova ejecta conditions. we find that some conditions of the neutrino-driven outflows consistently reproduce the observed abundances of our sample. in addition, from the successful combinations, the neutron-rich trajectories better reproduce the observed abundances of sr-zr ($z= 38-40$), while the proton-rich ones, mo-pd ($z= 42-47$). | neutrino-driven outflows and the elemental abundance patterns of very metal-poor stars |
a thorough understanding of neutrino cross sections in a wide range of energies is crucial for the successful execution of the entire neutrino physics program. in order to extract neutrino properties, long-baseline experiments need an accurate determination of neutrino cross sections within their detector(s). since very few of the needed neutrino cross sections across the energy spectrum are directly measured, we emphasize the need for theoretical input and indirect measurements such as electron scattering, which would complement direct measurements. in this report we briefly summarize the current status of our knowledge of the neutrino cross sections and articulate needs of the experiments, ongoing and planned, at energies ranging from cevns and supernova neutrino energies to the dune and atmospheric neutrino energies. | snowmass neutrino frontier: neutrino interaction cross sections (nf06) topical group report |
the cosmic curvature $ \omega_{k,0} $ , which determines the spatial geometry of the universe, is an important parameter in modern cosmology. any deviation from $ \omega_{k,0}=0 $ would have a profound impact on the primordial inflation paradigm and fundamental physics. in this work, we adopt a cosmological model-independent method to test whether $ \omega_{k,0} $ deviates from zero. we use the gaussian process to reconstruct the reduced hubble parameter $ e(z) $ and the derivative of the distance $ d'(z) $ from observational data and then determine $ \omega_{k,0} $ with a null test relation. the cosmic chronometer (cc) hubble data, baryon acoustic oscillation (bao) hubble data, and supernovae pantheon sample are considered. our result is consistent with a spatially flat universe within the domain of reconstruction $ 0 \lt z \lt 2.3 $ , at the $ 1\sigma $ confidence level. in the redshift interval $ 0 \lt z \lt 1 $ , the result favors a flat universe, while at $ z \gt 1 $ , it tends to favor a closed universe. in this sense, there is still a possibility for a closed universe. we also carry out the null test of the cosmic curvature at $ 0 \lt z \lt 4.5 $ using the simulated gravitational wave standard sirens, cc+bao, and redshift drift hubble data. the result indicates that in the future, with the synergy of multiple high-quality observations, we can tightly constrain the spatial geometry or exclude the flat universe. *supported by the national ska program of china (2022ska0110200, 2022ska0110203) and the national natural science foundation of china (11975072, 11835009, 11875102) | null test for cosmic curvature using gaussian process |
the giant spiral galaxy m101 is host to the nearest recent type ia supernova (sn 2011fe) and thus has been extensively monitored in the near-infrared to study the late-time lightcurve of the supernova. leveraging this existing baseline of observations, we derive the first mira-based distance to m101 by discovering and classifying a sample of 211 miras with periods ranging from 240 to 400 days in the supernova field. combined with new hst wfc3/ir channel observations, our dataset totals 11 epochs of f110w (hst $yj$) and 13 epochs of f160w (hst $h$) data spanning $\sim$2900 days. we adopt absolute calibrations of the mira period-luminosity relation based on geometric distances to the large magellanic cloud and the water megamaser host galaxy ngc 4258, and find $\mu_{\rm m101} = $ 29.10 $\pm$ 0.06 mag. this distance is in 1$\sigma$ agreement with most other recent cepheid and tip of the red giant branch distance measurements to m101. including the previous mira-snia host, ngc 1559 and sn 2005df, we determine the fiducial sn ia peak luminosity, $m^0_b = -19.27 \pm 0.09$ mag. with the hubble diagram of sne ia, we derive $h_0 = 72.37 \pm 2.97 $ km s$^{-1}$mpc$^{-1}$, a $4.1\%$ measurement of $h_0$ using miras. we find excellent agreement with recent cepheid distance ladder measurements of $h_0$ and confirm previous indications that the local universe value of $h_0$ is higher than the early-universe value at $\sim$ $95\%$ confidence. currently, the mira-based $h_0$ measurement is still dominated by the statistical uncertainty in the sn ia peak magnitude. | the mira distance to m101 and a 4% measurement of h0 |
we train graph neural networks to perform field-level likelihood-free inference using galaxy catalogs from state-of-the-art hydrodynamic simulations of the camels project. our models are rotational, translational, and permutation invariant and do not impose any cut on scale. from galaxy catalogs that only contain 3d positions and radial velocities of ~1000 galaxies in tiny ${(25\,{h}^{-1}\mathrm{mpc})}^{3}$ volumes our models can infer the value of ωm with approximately 12% precision. more importantly, by testing the models on galaxy catalogs from thousands of hydrodynamic simulations, each having a different efficiency of supernova and active galactic nucleus feedback, run with five different codes and subgrid models-illustristng, simba, astrid, magneticum, swift-eagle-we find that our models are robust to changes in astrophysics, subgrid physics, and subhalo/galaxy finder. furthermore, we test our models on 1024 simulations that cover a vast region in parameter space-variations in five cosmological and 23 astrophysical parameters-finding that the model extrapolates really well. our results indicate that the key to building a robust model is the use of both galaxy positions and velocities, suggesting that the network has likely learned an underlying physical relation that does not depend on galaxy formation and is valid on scales larger than ~10 h -1 kpc. | robust field-level likelihood-free inference with galaxies |
compose (compstar online supernovae equations of state) is an online repository of equations of state (eos) for use in nuclear physics and astrophysics, e.g., in the description of compact stars or the simulation of core-collapse supernovae and neutron-star mergers, see http://compose.obspm.fr. the main services, offered via the website, are: a collection of data tables in a flexible and easily extendable data format for different eos types and related physical quantities with extensive documentation and referencing; software for download to extract and to interpolate these data and to calculate additional quantities; webtools to generate eos tables that are customized to the needs of the users and to illustrate dependencies of various eos quantities in graphical form. this manual is an update of previous versions that are available on the compose website, at arxiv:1307.5715 [astro-ph.sr], and that was originally published in the journal "physics of particles and nuclei" with doi:10.1134/s1063779615040061. it contains a detailed description of the service, containing a general introduction as well as instructions for potential contributors and for users. short versions of the manual for eos users and providers will also be available as separate publications. | compose reference manual |
in order to better understand the relationship between feedback and galactic chemical evolution, we have developed a new model for stellar feedback at grid resolutions of only a few parsecs in global disc simulations, using the adaptive mesh refinement hydrodynamics code enzo. for the first time in galaxy-scale simulations, we simulate detailed stellar feedback from individual stars including asymptotic giant branch winds, photoelectric heating, lyman-werner radiation, ionizing radiation tracked through an adaptive ray-tracing radiative transfer method, and core-collapse and type ia supernovae. we furthermore follow the star-by-star chemical yields using tracer fields for 15 metal species: c, n, o, na, mg, si, s, ca, mn, fe, ni, as, sr, y, and ba. we include the yields ejected in massive stellar winds, but greatly reduce the winds' velocities due to computational constraints. we describe these methods in detail in this work and present the first results from 500 myr of evolution of an isolated dwarf galaxy with properties similar to a local group, low-mass dwarf galaxy. we demonstrate that our physics and feedback model is capable of producing a dwarf galaxy whose evolution is consistent with observations in both the kennicutt-schmidt relationship and extended schmidt relationship. effective feedback drives outflows with a greater metallicity than the interstellar medium (ism), leading to low metal retention fractions consistent with observations. finally, we demonstrate that these simulations yield valuable information on the variation in mixing behaviour of individual metal species within the multiphase ism. | simulating an isolated dwarf galaxy with multichannel feedback and chemical yields from individual stars |
current cosmological analyses, which use type ia supernova observations, combine supernova (sn) samples to expand the redshift range beyond that of a single sample and increase the overall sample size. the inhomogeneous photometric calibration between different sn samples is one of the largest systematic uncertainties of the cosmological parameter estimation. to place these different samples on a single system, analyses currently use observations of a small sample of very bright flux standards on the hubble space telescope system. we propose a complementary method, called “supercal,” in which we use measurements of secondary standards in each system, compare these to measurements of the same stars in the pan-starrs1 (ps1) system, and determine the offsets for each system relative to ps1, placing all sn observations on a single, consistent photometric system. ps1 has observed 3π of the sky and has a relative calibration of better than 5 mmag (for ∼15 < griz < 21 mag), making it an ideal reference system. we use this process to recalibrate optical observations taken by the following sn samples: ps1, supernova legacy survey, sdss, csp, and cfa1-4. we measure discrepancies on average of 10 mmag, but up to 35 mmag, in various optical passbands. we find that correcting for these differences changes the recovered values for the dark energy equation of state parameter, w, by an average of 2.6%. this change is roughly half the size of current statistical constraints on w. the size of this effect strongly depends on the error in the b - v calibration of the low-z surveys. the supercal method will allow future analyses to tie past samples to the best calibrated sample. | supercal: cross-calibration of multiple photometric systems to improve cosmological measurements with type ia supernovae |
we present a comprehensive study of an unbiased sample of 150 nearby (median redshift, z = 0.014) core-collapse supernova (ccsn) host galaxies drawn from the all-sky automated survey for supernovae (asas-sn) for direct comparison to the nearest long-duration gamma-ray burst (lgrb) and superluminous supernova (slsn) hosts. we use public imaging surveys to gather multiwavelength photometry for all ccsn host galaxies and fit their spectral energy distributions (seds) to derive stellar masses and integrated star formation rates (sfrs). ccsne populate galaxies across a wide range of stellar masses, from blue and compact dwarf galaxies to large spiral galaxies. we find 33$^{+4}_{-4}$ per cent of ccsne are in dwarf galaxies (m* < 109 m⊙) and 2$^{+2}_{-1}$ per cent are in dwarf starburst galaxies [specific star formation rate (ssfr) > 10-8 yr-1]. we reanalyse low-redshift slsn and lgrb hosts from the literature (out to z < 0.3) in a homogeneous way and compare against the ccsn host sample. the relative slsn to ccsn supernova rate is increased in low-mass galaxies and at high ssfrs. these parameters are strongly covariant and we cannot break the degeneracy between them with our current sample, although there is some evidence that both factors may play a role. larger unbiased samples of ccsne from projects such as ztf and lsst will be needed to determine whether host-galaxy mass (a proxy for metallicity) or ssfr (a proxy for star formation intensity and potential imf variation) is more fundamental in driving the preference for slsne and lgrbs in unusual galaxy environments. | core-collapse, superluminous, and gamma-ray burst supernova host galaxy populations at low redshift: the importance of dwarf and starbursting galaxies |
using a set of high-resolution hydrodynamical simulations run with the cholla code, we investigate how mass and momentum couple to the multiphase components of galactic winds. the simulations model the interaction between a hot wind driven by supernova explosions and a cooler, denser cloud of interstellar or circumgalactic media. by resolving scales of {{δ }}x< 0.1 pc over > 100 pc distances, our calculations capture how the cloud disruption leads to a distribution of densities and temperatures in the resulting multiphase outflow and quantify the mass and momentum associated with each phase. we find that the multiphase wind contains comparable mass and momenta in phases over a wide range of densities and temperatures extending from the hot wind (n≈ {10}-2.5 {{cm}}-3, t≈ {10}6.5 k) to the coldest components (n≈ {10}2 {{cm}}-3, t≈ {10}2 k). we further find that the momentum distributes roughly in proportion to the mass in each phase, and the mass loading of the hot phase by the destruction of cold, dense material is an efficient process. these results provide new insight into the physical origin of observed multiphase galactic outflows and inform galaxy formation models that include coarser treatments of galactic winds. our results confirm that cool gas observed in outflows at large distances from the galaxy (≳ 1 kpc) likely does not originate through the entrainment of cold material near the central starburst. | hydrodynamical coupling of mass and momentum in multiphase galactic winds |
this chapter describes the current classification scheme of supernovae (sne). this scheme has evolved over many decades and now includes numerous sn types and subtypes, many universally recognized, others controversial. the types are defined according to observational properties, mostly visible-light spectra near maximum light, as well as photometric properties. however, a long-term goal of sn classification is to associate observationally defined classes with specific physical explosive phenomena. we show here that this aspiration is now finally coming to fruition, and we establish the sn classification scheme upon direct observational evidence connecting sn groups with specific progenitor stars. observationally, the broad class of type ii sne contains objects showing strong spectroscopic signatures of hydrogen, while objects lacking such signatures are of type i, which is further divided to numerous subclasses. recently a class of superluminous sne (slsne, typically ten times more luminous than standard events) has been identified. finally we describe an alternative classification scheme that presents our emerging physical understanding of sn explosions, while clearly separating robust observational properties from physical inferences that can be debated. this new system is quantitative, with events distributed along a continuum, rather than divided into discrete classes. thus, it may be more suitable to the coming era where sn numbers will reach millions. | observational and physical classification of supernovae |
the sno+ experiment is located 2 km underground at snolab in sudbury, canada. a low background search for neutrinoless double beta (0νββ) decay will be conducted using 780 tonnes of liquid scintillator loaded with 3.9 tonnes of natural tellurium, corresponding to 1.3 tonnes of 130te. this paper provides a general overview of the sno+ experiment, including detector design, construction of process plants, commissioning efforts, electronics upgrades, data acquisition systems, and calibration techniques. the sno+ collaboration is reusing the acrylic vessel, pmt array, and electronics of the sno detector, having made a number of experimental upgrades and essential adaptations for use with the liquid scintillator. with low backgrounds and a low energy threshold, the sno+ collaboration will also pursue a rich physics program beyond the search for 0νββ decay, including studies of geo- and reactor antineutrinos, supernova and solar neutrinos, and exotic physics such as the search for invisible nucleon decay. the sno+ approach to the search for 0νββ decay is scalable: a future phase with high 130te-loading is envisioned to probe an effective majorana mass in the inverted mass ordering region. | the sno+ experiment |
we present cosmological, radiation-hydrodynamics simulations of galaxy formation during the epoch of reionization in an effort towards modelling the interstellar medium (ism) and interpreting atacama large millimeter array (alma) observations. simulations with and without stellar radiation are compared at large (mpc), intermediate (tens of kpc) and small (sub-kpc) scales. at large scales, the dense regions around galaxies reionize first before ultraviolet (uv) photons penetrate the voids; however, considerable amounts of neutral gas remain present within the haloes. the spatial distribution of neutral gas is highly dynamic and is anticorrelated with the presence of stars older than a few myr. for our specific feedback implementation, most of the metals remain inside the virial radii of haloes, and they are proportionally distributed over the ionized and neutral media by mass. for our most massive galaxy with mh ∼ 1011 m⊙, the majority of the c ii and o i masses are associated with cold neutral clumps. n ii is more diffuse and arises in warmer gas, while o iii arises in hotter gas with a higher ionization parameter, produced by photoheating and supernovae. if smaller pockets of high-metallicity gas exist in the ism, the emission from these ions may be observable by alma, while the low metallicity of the galaxy may cause these systems to fall below the local [c ii]-star formation rate relation. the presence of dust can cause spatial offsets between uv/lyman α and [c ii] emissions, as suggested by the recent observations of maiolino et al. [o iii] may be spatially offset from both of these components since it arises from a different part of density-temperature phase space. | interpreting alma observations of the ism during the epoch of reionization |
two-dimensional (2d) materials, such as transition metal dichalcogenides (tmds), black phosphorus (bp), mxene and borophene, have aroused extensive attention since the discovery of graphene in 2004. they have wide range of applications in many research fields, such as optoelectronic devices, energy storage, catalysis, owing to their striking physical and chemical properties. among them, anisotropic 2d material is one kind of 2d materials that possess different properties along different directions caused by the intrinsic anisotropic atoms' arrangement of the 2d materials, mainly including bp, borophene, low-symmetry tmds (rese2 and res2) and group iv monochalcogenides (sns, snse, ges, and gese). recently, a series of new devices has been fabricated based on these anisotropic 2d materials. in this review, we start from a brief introduction of the classifications, crystal structures, preparation techniques, stability, as well as the strategy to discriminate the anisotropic characteristics of 2d materials. then, the recent advanced applications including electronic devices, optoelectronic devices, thermoelectric devices and nanomechanical devices based on the anisotropic 2d materials both in experiment and theory have been summarized. finally, the current challenges and prospects in device designs, integration, mechanical analysis, and micro-/nano-fabrication techniques related to anisotropic 2d materials have been discussed. this review is aimed to give a generalized knowledge of anisotropic 2d materials and their current devices applications, and thus inspiring the exploration and development of other kinds of new anisotropic 2d materials and various novel device applications. | recent advances in anisotropic two-dimensional materials and device applications |
van der waals heterojunctions (vdwhs) have gained extensive attention because they can integrate the excellent characteristics of the stacked materials and most vdwhs exhibit type-ii band alignment. however, type-iii vdwhs with broken gaps are still very rare, which limits the development and application of two-dimensional (2d) materials in the fields of tunnel fets (tfets). here, we theoretically demonstrate that 2d phosphorene/sns 2 (snse 2) vdwhs possess type-iii (broken-gap) band alignment, and their i-v curves present negative differential resistance (ndr) effects. the btbt transport mechanism and its applications in tfets are analyzed. interestingly, a positive electric field can enlarge the tunnelling window and a negative electric field can realize multiple-band-alignment transformation (type i, type ii, and type iii). thus, this work presents the intrinsic physics mechanism and electric field tunable multiple-band alignments in 2d type-iii vdwhs and related electronic devices. | effects of electric field on the electronic structures of broken-gap phosphorene/sn x2 (x = s , se ) van der waals heterojunctions |
we present the pmas/ppak integral-field supernova hosts compilation (pisco), which comprises integral field spectroscopy (ifs) of 232 supernova (sn) host galaxies that hosted 272 sne, observed over several semesters with the 3.5 m telescope at the calar alto observatory (caha). pisco is the largest collection of sn host galaxies observed with wide-field ifs, totaling 466,347 individual spectra covering a typical spatial resolution of ∼380 pc. focused studies regarding specific sn ia-related topics will be published elsewhere; this paper aims to present the properties of the sn environments, using stellar population (sp) synthesis, and the gas-phase interstellar medium, providing additional results separating stripped-envelope sne into their subtypes. with 11,270 h ii regions detected in all galaxies, we present for the first time a statistical analysis of h ii regions, which puts h ii regions that have hosted sne in context with all other star-forming clumps within their galaxies. sne ic are associated with environments that are more metal-rich and have higher ew(hα) and higher star formation rate within their host galaxies than the mean of all h ii regions detected within each host. this in contrast to sne iib, which occur in environments that are very different compared to other core-collapse sne types. we find two clear components of young and old sps at sne iin locations. we find that sne ii fast decliners tend to explode at locations where the σsfr is more intense. finally, we outline how a future dedicated ifs survey of galaxies in parallel to an untargeted sn search would overcome the biases in current environmental studies. | pisco: the pmas/ppak integral-field supernova hosts compilation |
we investigate the constraints on total neutrino mass in the scenario of vacuum energy interacting with cold dark matter. we focus on two typical interaction forms, i.e., q = βh ρ c and q = βh ρ λ. to avoid the occurrence of large-scale instability in interacting dark energy cosmology, we adopt the parameterized post-friedmann approach to calculate the perturbation evolution of dark energy. we employ observational data, including the planck cosmic microwave background temperature and polarization data, baryon acoustic oscillation data, a jla sample of type ia supernovae observation, direct measurement of the hubble constant, and redshift space distortion data. we find that, compared with those in the λcdm model, much looser constraints on σmν are obtained in the q = βh ρ c model, whereas slightly tighter constraints are obtained in the q = βh ρ λ model. consideration of the possible mass hierarchies of neutrinos reveals that the smallest upper limit of σmν appears in the degenerate hierarchy case. by comparing the values of {χ }{{\min }}2, we find that the normal hierarchy case is favored over the inverted one. in particular, we find that the difference δ {χ }{{\min }}2\equiv {χ }{{ih};{{\min }}}2-{χ }{{nh};min}2> 2 in the q = βh ρ c model. in addition, we find that β = 0 is consistent with the current observations in the q = βh ρ c model, and β < 0 is favored at more than the 1 σ level in the q = βh ρ λ model. supported by national natural science foundation of china (11522540, 11690021), the top-notch young talents program of china and the provincial department of education of liaoning (l2012087) | exploring neutrino mass and mass hierarchy in the scenario of vacuum energy interacting with cold dark matte |
we adopt a cosmographic approach in order to determine spatial curvature (i.e. ωk), combining the latest release of cosmic chronometer (cc) data, the pantheon sample of type ia supernovae observations and baryon acoustic oscillation measurements. we use the expanded transverse comoving distance dm(z) as a basic function for deriving h(z) and other cosmic distances. in this scenario, ωk can be constrained only by cc data. to overcome the convergence issues at high-redshift domains, two methods are applied: the padé approximants and the taylor series in terms of the new redshift y = z/(1 + z). adopting the bayesian evidence, we find that there is positive evidence for the padé approximant up to order (2,2) and weak evidence for the taylor series up to third order against the λcdm + ωk model. the constraint results show that a closed universe is preferred by present observations under all the approximations used in this study. also, the tension level of the hubble constant h0 has less than 2σ significance between different approximations and the local distance ladder determination. for each assumed approximation, h0 is anticorrelated with ωk and the sound horizon at the end of the radiation drag epoch, which indicates that the h0 tension problem can be slightly relaxed by introducing ωk or any new physics that can reduce the sound horizon in the early universe. | general cosmography model with spatial curvature |
we will follow the two-families scenario described in the accompanying paper, in which compact stars having a very small radius and masses not exceeding about 1.5 m ⊙ are made of hadrons, while more massive compact stars are quark stars. in the present paper we discuss the dynamics of the transition of a hadronic star into a quark star. we will show that the transition takes place in two phases: a very rapid one, lasting a few milliseconds, during which the central region of the star converts into quark matter and the process of conversion is accelerated by the existence of strong hydrodynamical instabilities, and a second phase, lasting about ten seconds, during which the process of conversion proceeds as far as the surface of the star via production and diffusion of strangeness. we will show that these two steps play a crucial role in the phenomenological implications of the model. we will discuss the possible implications of this scenario both for long and for short gamma ray bursts (grbs), using the proto-magnetar model as the reference frame of our discussion. we will show that the process of quark deconfinement can be connected to specific observed features of the grbs. in the case of long grbs we will discuss the possibility that quark deconfinement is at the origin of the second peak present in quite a large fraction of bursts. also we will discuss the possibility that long grbs can take place in binary systems without being associated with a sn explosion. concerning short grbs, quark deconfinement can play the crucial role in limiting their duration. finally we will shortly revisit the possible relevance of quark deconfinement in some specific type of supernova explosions, in particular in the case of very massive progenitors. | the scenario of two families of compact stars. part 2: transition from hadronic to quark matter and explosive phenomena |
the merger of binary neutron stars (nss) ejects a small quantity of neutron-rich matter, the radioactive decay of which powers a day to week long thermal transient known as a kilonova. most of the ejecta remains sufficiently dense during its expansion that all neutrons are captured into nuclei during the r-process. however, recent general relativistic merger simulations by bauswein and collaborators show that a small fraction of the ejected mass (a few per cent, or ∼10-4 m⊙) expands sufficiently rapidly for most neutrons to avoid capture. this matter originates from the shocked-heated interface between the merging nss. here, we show that the β-decay of these free neutrons in the outermost ejecta powers a `precursor' to the main kilonova emission, which peaks on a time-scale of ∼ few hours following merger at u-band magnitude ∼22 (for an assumed distance of 200 mpc). the high luminosity and blue colours of the neutron precursor render it a potentially important counterpart to the gravitational wave source, that may encode valuable information on the properties of the merging binary (e.g. ns-ns versus ns-black hole) and the ns equation of state. future work is necessary to assess the robustness of the fast-moving ejecta and the survival of free neutrons in the face of neutrino absorptions, although the precursor properties are robust to a moderate amount of leptonization. our results provide additional motivation for short latency gravitational wave triggers and rapid follow-up searches with sensitive ground-based telescopes. | neutron-powered precursors of kilonovae |
the all-sky medium energy gamma-ray observatory explorer (amego-x) is designed to identify and characterize gamma rays from extreme explosions and accelerators. the main science themes include supermassive black holes and their connections to neutrinos and cosmic rays; binary neutron star mergers and the relativistic jets they produce; cosmic ray particle acceleration sources including galactic supernovae; continuous monitoring of other astrophysical events and sources over the full sky in this important energy range. amego-x will probe the medium energy gamma-ray band using a single instrument with sensitivity up to an order of magnitude greater than previous telescopes in the energy range 100 kev to 1 gev that can be only realized in space. during its 3-year baseline mission, amego-x will observe nearly the entire sky every two orbits, building up a sensitive all-sky map of gamma-ray sources and emissions. amego-x was submitted in the recent 2021 nasa midex announcement of opportunity. | all-sky medium energy gamma-ray observatory explorer mission concept |
one of the key mysteries of star formation is the origin of the stellar initial mass function (imf). the imf is observed to be nearly universal in the milky way and its satellites, and significant variations are only inferred in extreme environments, such as the cores of massive elliptical galaxies and the central molecular zone. in this work, we present simulations from the starforge project that are the first cloud-scale radiation-magnetohydrodynamic simulations that follow individual stars and include all relevant physical processes. the simulations include detailed gas thermodynamics, as well as stellar feedback in the form of protostellar jets, stellar radiation, winds, and supernovae. in this work, we focus on how stellar radiation, winds, and supernovae impact star-forming clouds. radiative feedback plays a major role in quenching star formation and disrupting the cloud; however, the imf peak is predominantly set by protostellar jet physics. we find that the effect of stellar winds is minor, and supernovae 'occur too late' to affect the imf or quench star formation. we also investigate the effects of initial conditions on the imf. we find that the imf is insensitive to the initial turbulence, cloud mass, and cloud surface density, even though these parameters significantly shape the star formation history of the cloud, including the final star formation efficiency. meanwhile, the characteristic stellar mass depends weakly on metallicity and the interstellar radiation field, which essentially set the average gas temperature. finally, while turbulent driving and the level of magnetization strongly influence the star formation history, they only influence the high-mass slope of the imf. | effects of the environment and feedback physics on the initial mass function of stars in the starforge simulations |
we determine the proper motion of the solar system from the pantheon sample of type ia supernovae (sne). the posterior distribution of the solar system proper velocity, its direction, and relevant cosmological parameters were obtained based on the observed distance moduli, heliocentric redshifts, and positions of sne by means of a markov chain monte carlo method. we accounted for the unknown peculiar motion of sne by including their expected covariance from linear theory. we find that the solar system moves with vo = 249 ± 51 km s−1 towards ra = 166 ± 16 deg, dec = 10 ± 19 deg (j2000), (all at 68% c.l.). the direction of motion agrees with the direction of the dipole observed in the cosmic microwave background (cmb) (ra = 166 deg, dec = −7 deg). the inferred velocity is 2.4σ lower than the value inferred from a purely kinematic interpretation of the cmb dipole (370 km s−1). assuming a flat λ cold dark matter model, we find no degeneracy of solar proper motion with other cosmological parameters. the dimensionless matter density, ωm = 0.305 ± 0.022, is in excellent agreement with cmb measurements. we also find no degeneracy of the solar proper motion with the sn calibration nuisance parameter. bulk flows might be able to explain why the solar motion appears to be slower than that of nearby sne. we conclude that a larger sample of sne, distributed over wide areas of the sky and a broad range in redshift, will allow an independent and robust test of the kinematic nature of the cmb dipole. sn data is only available at the cds via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/j/a+a/668/a34 | inference of the cosmic rest-frame from supernovae ia |
we present analysis of the light curves (lcs) of 77 hydrogen-poor superluminous supernovae (slsne i) discovered during the zwicky transient facility phase i operation. we find that the majority (67%) of the sample can be fit equally well by both magnetar and ejecta-circumstellar medium (csm) interaction plus 56ni decay models. this implies that lcs alone cannot unambiguously constrain the physical power sources for an slsn i. however, 23% of the sample show inverted v-shape, steep-declining lcs or features of long rise and fast post-peak decay, which are better described by the csm+ni model. the remaining 10% of the sample favors the magnetar model. moreover, our analysis shows that the lc undulations are quite common, with a fraction of 18%-44% in our gold sample. among those strongly undulating events, about 62% of them are found to be csm-favored, implying that the undulations tend to occur in the csm-favored events. undulations show a wide range in energy and duration, with median values (and 1σ errors) being as $1.7{ \% }_{-0.7 \% }^{+1.5 \% }\,{e}_{\mathrm{rad},\mathrm{total}}$ and ${28.8}_{-9.1}^{+14.4}$ days, respectively. our analysis of the undulation timescales suggests that intrinsic temporal variations of the central engine can explain half of the undulating events, while csm interaction (csi) can account for the majority of the sample. finally, all of the well-observed he-rich slsne ib either have strongly undulating lcs or the lcs are much better fit by the csm+ni model. these observations imply that their progenitor stars have not had enough time to lose all of the he-envelopes before supernova explosions, and h-poor csm are likely to present in these events. | the hydrogen-poor superluminous supernovae from the zwicky transient facility phase i survey. ii. light-curve modeling and characterization of undulations |
during the core collapse of massive stars that do not undergo a canonical energetic explosion, some of the hydrogen envelope of a red supergiant (rsg) progenitor may infall on to the newborn black hole (bh). within the athena++ framework, we perform 3d, hydrodynamical simulations of idealized models of supergiant convection and collapse in order to assess whether the infall of the convective envelope can give rise to rotationally supported material, even if the star has zero angular momentum overall. our dimension-less, polytropic models are applicable to the optically thick hydrogen envelope of non-rotating rsgs and cover a factor of 20 in stellar radius. at all radii, the specific angular momentum due to random convective flows implies associated circularization radii of 10-1500 times the innermost stable circular orbit of the bh. during collapse, the angular momentum vector of the convective flows is approximately conserved and is slowly varying on the time-scale relevant to forming discs at small radii. our results indicate that otherwise failed explosions of rsgs lead to the formation of rotationally supported flows that are capable of driving outflows to large radii and powering observable transients. when the bh is able to accrete most of the hydrogen envelope, the final bh spin parameter is ~ 0.5, even though the star is non-rotating. for fractional accretion of the envelope, the spin parameter is generally lower and never exceeds 0.8. we discuss the implications of our results for transients produced by rsg collapse to a black hole. | numerical simulations of the random angular momentum in convection: implications for supergiant collapse to form black holes |
in the present paper, we investigate the dark energy equation of state using the gaussian processes analysis method, without confining a particular parametrization. the reconstruction is carried out by adopting the background data including supernova and hubble parameter, and perturbation data from the growth rate. it suggests that the background and perturbation data both present a hint of dynamical dark energy. however, the perturbation data have a more promising potential to distinguish non-evolution dark energy including the cosmological constant model. we also test the influence of some parameters on the reconstruction. we find that the matter density parameter ω _{m0} has a slight effect on the background data reconstruction, but has a notable influence on the perturbation data reconstruction. while the hubble constant presents a significant influence on the reconstruction from background data. | gaussian processes reconstruction of dark energy from observational data |
we propose to use the unique event topology and reconstruction capabilities of liquid argon time projection chambers to study sub-gev atmospheric neutrinos. the detection of low energy recoiled protons in dune allows for a determination of the leptonic c p -violating phase independent from the accelerator neutrino measurement. our findings indicate that this analysis can exclude a range of values of δc p beyond the 3 σ level. moreover, the determination of the sub-gev atmospheric neutrino flux will have important consequences in the detection of diffuse supernova neutrinos and in dark matter experiments. | sub-gev atmospheric neutrinos and c p violation in dune |
we show that the number of observed voids in galaxy redshift surveys is a sensitive function of the equation of state of dark energy. using the fisher matrix formalism, we find the error ellipses in the w0-wa plane when the equation of state of dark energy is assumed to be of the form wcpl(z )=w0+waz /(1 +z ) . we forecast the number of voids to be observed with the esa euclid satellite and the nasa wfirst mission, taking into account updated details of the surveys to reach accurate estimates of their power. the theoretical model for the forecast of the number of voids is based on matches between abundances in simulations and the analytical prediction. to take into account the uncertainties within the model, we marginalize over its free parameters when calculating the fisher matrices. the addition of the void abundance constraints to the data from planck, hst and supernova survey data noticeably tighten the w0-wa parameter space. we, thus, quantify the improvement in the constraints due to the use of voids and demonstrate that the void abundance is a sensitive new probe for the dark energy equation of state. | counting voids to probe dark energy |
young stars typically form in star clusters, so the supernovae (sne) they produce are clustered in space and time. this clustering of sne may alter the momentum per sn deposited in the interstellar medium (ism) by affecting the local ism density, which in turn affects the cooling rate. we study the effect of multiple sne using idealized 1d hydrodynamic simulations which explore a large parameter space of the number of sne, and the background gas density and metallicity. the results are provided as a table and an analytic fitting formula. we find that for clusters with up to ∼100 sne, the asymptotic momentum scales superlinearly with the number of sne, resulting in a momentum per sn which can be an order of magnitude larger than for a single sn, with a maximum efficiency for clusters with 10-100 sne. we argue that additional physical processes not included in our simulations - self-gravity, breakout from a galactic disc, and galactic shear - can slightly reduce the momentum enhancement from clustering, but the average momentum per sn still remains a factor of 4 larger than the isolated sn value when averaged over a realistic cluster mass function for a star-forming galaxy. we conclude with a discussion of the possible role of mixing between hot and cold gas, induced by multidimensional instabilities or pre-existing density variations, as a limiting factor in the build-up of momentum by clustered sne, and suggest future numerical experiments to explore these effects. | enhanced momentum feedback from clustered supernovae |
we assess the variance of the post-collapse evolution remnants of compact, massive, low-metallicity stars, under small changes in the degrees of rotation and magnetic field of selected pre-supernova cores. these stellar models are commonly considered progenitors of long gamma-ray bursts. the fate of the protoneutron star (pns) formed after the collapse, whose mass may continuously grow due to accretion, critically depends on the poloidal magnetic field strength at bounce. should the poloidal magnetic field be sufficiently weak, the pns collapses to a black hole (bh) within a few seconds. models on this evolutionary track contain promising collapsar engines. poloidal magnetic fields smooth over large radial scales (e.g. dipolar fields) or slightly augmented with respect to the original pre-supernova core yield long-lasting pnss. in these models, bh formation is avoided or staved off for a long time, hence, they may produce protomagnetars (pms). some of our pm candidates have been run for $\lesssim 10\,$ s after core bounce, but they have not entered the kelvin-helmholtz phase yet. among these models, some display episodic events of spin-down during which we find properties broadly compatible with the theoretical expectations for pms ( $m_\rm {\small pns}\approx 1.85{-}2.5\, \mathrm{m}_{\odot }$ , $\bar{p}_\rm {\small pns}\approx 1.5 {-} 4\,$ ms, and $b^{\rm surf}_\rm {\small pns}\lesssim 10^{15}\,$ g) and their very collimated supernova ejecta have nearly reached the stellar surface with (still growing) explosion energies $\gtrsim {2} \times 10^{51}\, \textrm {erg}$ . | magnetorotational core collapse of possible grb progenitors - ii. formation of protomagnetars and collapsars |
we present photometric and spectroscopic observations of the extraordinary gamma-ray burst (grb) 221009a in search of an associated supernova. some past grbs have shown bumps in the optical light curve that coincide with the emergence of supernova spectral features, but we do not detect any significant light-curve features in grb 221009a, nor do we detect any clear sign of supernova spectral features. using two well-studied grb-associated supernovae (sn 2013dx, ${m}_{r,\max }=-19.54;$ sn 2016jca, ${m}_{r,\max }=-19.04$ ) at a similar redshift as grb 221009a (z = 0.151), we modeled how the emergence of a supernova would affect the light curve. if we assume the grb afterglow to decay at the same rate as the x-ray data, the combination of afterglow and a supernova component is fainter than the observed grb brightness. for the case where we assume the best-fit power law to the optical data as the grb afterglow component, a supernova contribution should have created a clear bump in the light curve, assuming only extinction from the milky way. if we assume a higher extinction of e(b - v) = 1.74 mag (as has been suggested elsewhere), the supernova contribution would have been hard to detect, with a limit on the associated supernova of ${m}_{r,\max }\approx -$ 19.54. we do not observe any clear supernova features in our spectra, which were taken around the time of expected maximum light. the lack of a bright supernova associated with grb 221009a may indicate that the energy from the explosion is mostly concentrated in the jet, leaving a lower energy budget available for the supernova. | limit on supernova emission in the brightest gamma-ray burst, grb 221009a |
we carried out a detailed strong lensing analysis of a sub-sample of eight galaxy clusters of the cluster lensing and supernova survey with hubble (clash) in the redshift range of zcluster = [0.23 - 0.59] using extensive spectroscopic information, primarily from the multi unit spectroscopic explorer (muse) archival data and complemented with clash-vlt redshift measurements. the observed positions of the multiple images of strongly lensed background sources were used to constrain parametric models describing the cluster total mass distributions. different models were tested in each cluster depending on the complexity of its mass distribution and on the number of detected multiple images. four clusters show more than five spectroscopically confirmed multiple image families. in this sample, we did not make use of families that are only photometrically identified in order to reduce model degeneracies between the values of the total mass of a cluster source redshifts, in addition to systematics due to the potential misidentifications of multiple images. for the remaining four clusters, we used additional families without any spectroscopic confirmation to increase the number of strong lensing constraints up to the number of free parameters in our parametric models. we present spectroscopic confirmation of 27 multiply lensed sources, with no previous spectroscopic measurements, spanning over the redshift range of zsrc = [0.7 - 6.1]. moreover, we confirm an average of 48 galaxy members in the core of each cluster thanks to the high efficiency and large field of view of muse. we used this information to derive precise strong lensing models, projected total mass distributions, and magnification maps. we show that, despite having different properties (i.e. number of mass components, total mass, redshift, etc.), the projected total mass and mass density profiles of all clusters have very similar shapes when rescaled by independent measurements of m200c and r200c. specifically, we measured the mean value of the projected total mass of our cluster sample within 10 (20)% of r200c to be 0.13 (0.32) of m200c, with a remarkably small scatter of 5 (6)%. furthermore, the large number of high-z sources and the precise magnification maps derived in this work for four clusters add up to the sample of high-quality gravitational telescopes to be used to study the faint and distant universe. the full redshift catalogue from the muse observations (table 2) is only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/632/a36 | strong lensing models of eight clash clusters from extensive spectroscopy: accurate total mass reconstructions in the cores |
palomar gattini-ir is a new wide-field, near-infrared (nir) robotic time domain survey operating at palomar observatory. using a 30 cm telescope mounted with a h2rg detector, gattini-ir achieves a field of view (fov) of 25 sq. deg. with a pixel scale of 8.″7 in j-band. here, we describe the system design, survey operations, data processing system and on-sky performance of palomar gattini-ir. as a part of the nominal survey, gattini-ir scans ≈7500 square degrees of the sky every night to a median 5σ depth of 15.7 ab mag outside the galactic plane. the survey covers ≈15,000 square degrees of the sky visible from palomar with a median cadence of 2 days. a real-time data processing system produces stacked science images from dithered raw images taken on sky, together with point-spread function (psf)-fit source catalogs and transient candidates identified from subtractions within a median delay of ≈4 hr from the time of observation. the calibrated data products achieve an astrometric accuracy (rms) of ≈0.″7 with respect to gaia dr2 for sources with signal-to-noise ratio > 10, and better than ≈0.″35 for sources brighter than ≈12 vega mag. the photometric accuracy (rms) achieved in the psf-fit source catalogs is better than ≈3% for sources brighter than ≈12 vega mag and fainter than the saturation magnitude of ≈8.5 vega mag, as calibrated against the two micron all sky survey catalog. the detection efficiency of transient candidates injected into the images is better than 90% for sources brighter than the 5σ limiting magnitude. the photometric recovery precision of injected sources is 3% for sources brighter than 13 mag, and the astrometric recovery rms is ≈0.″9. reference images generated by stacking several field visits achieve depths of ≳16.5 ab mag over 60% of the sky, while it is limited by confusion in the galactic plane. with a fov ≈40× larger than any other existing nir imaging instrument, gattini-ir is probing the reddest and dustiest transients in the local universe such as dust obscured supernovae in nearby galaxies, novae behind large columns of extinction within the galaxy, reddened microlensing events in the galactic plane and variability from cool and dust obscured stars. we present results from transients and variables identified since the start of the commissioning period. | palomar gattini-ir: survey overview, data processing system, on-sky performance and first results |
we study large-scale inhomogeneous perturbations and instabilities of interacting dark-energy models. past analysis of large-scale perturbative instabilities has shown that we can only test interacting dark-energy models with observational data when their parameter ranges are either wx≥-1 and ξ ≥0 , or wx≤-1 and ξ ≤0 , where wx is the dark-energy equation of state and ξ is a coupling parameter governing the strength and direction of the energy transfer. we show that by adding a factor (1 +wx ) to the background energy transfer, the whole parameter space can be tested against all the data, and thus, the instabilities in such interaction models can be removed. we test three classes of interaction models using the latest astronomical data from the cmb, supernovae, baryon acoustic oscillations, redshift-space distortions, weak lensing, cosmic chronometers, and the local hubble constant. precise constraints are found. our analysis shows that a very small but nonzero deviation from pure λ -cosmology is suggested by the observational data, while the no-interaction scenario can be recovered at the 68.3% confidence level. in particular, for three interacting dark-energy (ide) models, identified as ide 1, ide 2, and ide 3, the 68.3% confidence-level constraints on the interaction coupling strengths are ξ =0.036 0-0.0360+0.0091 (ide 1), ξ =0.043 3-0.0433+0.0062 (ide 2), ξ =0.106 4-0.1064+0.0437 (ide 3). in addition, we find that the dark-energy equation of state tends towards the phantom region. taking the 68.3% confidence-level constraints, wx=-1.023 0-0.0257+0.0329 (ide 1), wx=-1.024 7-0.0302+0.0289 (ide 2), and wx=-1.027 5-0.0318+0.0228 (ide 3). however, the possibility of wx>-1 is also not rejected by the astronomical data employed in this analysis. moreover, we find in all interaction models that, as the value of the hubble constant decreases, the behavior of the dark-energy equation of state shifts from a phantom to a quintessence type with its equation of state very close to that of a simple cosmological constant at the present time. finally, we compare the observational estimations of the coupling strength imposed on some interaction models studied in this work with the past constraints obtained on them for different regions of the dark-energy equation of state. | large-scale stability and astronomical constraints for coupled dark-energy models |
the description of nuclear reactions induced by supernova neutrinos has witnessed significant progress during the recent years. on one hand this progress is due to experimental data which serve as important constraints to model calculations, on the other hand it is related to advances in nuclear modeling itself and in computer hardware. at the energies and momentum transfers relevant for supernova neutrinos, neutrino-nucleus cross sections are dominated by allowed transitions, however, often with non-negligible contributions from (first) forbidden transitions. for several nuclei, allowed gamow-teller strength distributions have been derived from charge-exchange reactions and from inelastic electron scattering data. importantly the diagonalization shell model has been proven to accurately reproduce these data and hence became the appropriate tool to calculate the allowed contributions to neutrino-nucleus cross sections for supernova neutrinos. higher multipole contributions are usually calculated within the framework of the quasiparticle random phase approximation, which describes the total strength and the position of the giant resonances quite well. both are the relevant quantities for a reliable calculation of the forbidden contributions to the cross sections. the current manuscript reviews the recent progress achieved in calculating supernova-relevant neutrino-nucleus cross sections and discusses its verification by data. moreover, the review summarizes also the impact which neutrino-nucleus reactions have on the dynamics of supernovae and on the associated nucleosynthesis. with relevance to the supernova dynamics, these include the absorption of neutrinos by nuclei (the inverse of nuclear electron capture which is the dominating weak-interaction process during collapse), inelastic neutrino-nucleus scattering and nuclear de-excitation by neutrino-pair emission. for supernova nucleosynthesis we discuss the role of neutrino-induced reactions for the recently discovered νp process, for the r-process and for the neutrino process, for which neutrino-nucleus reactions have the largest impact. finally we briefly review neutrino-nucleus reactions important for the observation of supernova neutrinos by earthbound detectors. | neutrino-nucleus reactions and their role for supernova dynamics and nucleosynthesis |
we present nearly 500 days of observations of the tidal disruption event (tde) asassn-18pg, spanning from 54 days before peak light to 441 days after peak light. our data set includes x-ray, uv, and optical photometry, optical spectroscopy, radio observations, and the first published spectropolarimetric observations of a tde. asassn-18pg was discovered on 2018 july 11 by the all-sky automated survey for supernovae (asas-sn) at a distance of d = 78.6 mpc; with a peak uv magnitude of m ≃ 14, it is both one of the nearest and brightest tdes discovered to-date. the photometric data allow us to track both the rise to peak and the long-term evolution of the tde. asassn-18pg peaked at a luminosity of l ≃ 2.4 × 1044 erg s-1, and its late-time evolution is shallower than a flux ∝t-5/3 power-law model, similar to what has been seen in other tdes. asassn-18pg exhibited balmer lines and spectroscopic features consistent with bowen fluorescence prior to peak, which remained detectable for roughly 225 days after peak. analysis of the two-component hα profile indicates that, if they are the result of reprocessing of emission from the accretion disk, the different spectroscopic lines may be coming from regions between ∼10 and ∼60 lt-days from the black hole. no x-ray emission is detected from the tde, and there is no evidence of a jet or strong outflow detected in the radio. our spectropolarimetric observations indicate that the projected emission region is likely not significantly aspherical, with the projected emission region having an axis ratio of ≳0.65. | the rise and fall of asassn-18pg: following a tde from early to late times |
we report on the impact of a probabilistic prescription for compact remnant masses and kicks on massive binary population synthesis. we find that this prescription populates the putative mass gap between neutron stars and black holes with low-mass black holes. however, evolutionary effects reduce the number of x-ray binary candidates with low-mass black holes, consistent with the dearth of such systems in the observed sample. we further find that this prescription is consistent with the formation of heavier binary neutron stars such as gw190425, but overpredicts the masses of galactic double neutron stars. the revised natal kicks, particularly increased ultra-stripped supernova kicks, do not directly explain the observed galactic double neutron star orbital period-eccentricity distribution. finally, this prescription allows for the formation of systems similar to the recently discovered extreme mass ratio binary gw190814, but only if we allow for the survival of binaries in which the common envelope is initiated by a donor crossing the hertzsprung gap, contrary to our standard model. | binary population synthesis with probabilistic remnant mass and kick prescriptions |
we analyze the formation and evolution of the stellar components in "eris," a 120 pc resolution cosmological hydrodynamic simulation of a late-type spiral galaxy. the simulation includes the effects of a uniform uv background, a delayed-radiative-cooling scheme for supernova feedback, and a star formation recipe based on a high gas density threshold. it allows a detailed study of the relative contributions of "in-situ" (within the main host) and "ex-situ" (within satellite galaxies) star formation to each major galactic component in a close milky way analog. we investigate these two star-formation channels as a function of galactocentric distance, along different lines of sight above and along the disk plane, and as a function of cosmic time. we find that: (1) approximately 70% of today's stars formed in-situ; (2) more than two thirds of the ex-situ stars formed within satellites after infall; (3) the majority of ex-situ stars are found today in the disk and in the bulge; (4) the stellar halo is dominated by ex-situ stars, whereas in-situ stars dominate the mass profile at distances <~ 5 kpc from the center at high latitudes; and (5) approximately 25% of the inner, r <~ 20 kpc, halo is composed of in-situ stars that have been displaced from their original birth sites during eris' early assembly history. | building late-type spiral galaxies by in-situ and ex-situ star formation |
standard sirens are the gravitational wave (gw) analog of the astronomical standard candles and can provide powerful information about the dynamics of the universe. in this work, we simulate a catalog with 1000 standard siren events from binary neutron star mergers, within the sensitivity predicted for the third generation of the ground gw detector called the einstein telescope (et). after correctly modifying the propagation of gws as input to generate the catalog, we apply our mock dataset on scalar-tensor theories where the speed of gw propagation is equal to the speed of light. as a first application, we find new observational bounds on the running of the planck mass, when considering appropriate values within the stability condition of the theory, and we discuss some consequences on the amplitude of the running of the planck mass. in the second part, we combine our simulated standard sirens catalog with other geometric cosmological tests (supernovae ia and cosmic chronometer measurements) to constrain the hu-sawicki f (r ) gravity model. we thus find new and non-null deviations from the standard λ cdm model, showing that in the future f (r ) gravity can be tested up to 95% confidence level. the results obtained here show that the statistical accuracy achievable by future ground-based gw observations, mainly with the et detector (and planned detectors with a similar sensitivity), can provide strong observational bounds on modified gravity theories. | probing observational bounds on scalar-tensor theories from standard sirens |
the localization of the repeating fast radio burst (frb) 121102 to a low-metallicity dwarf galaxy at z = 0.193, and its association with a luminous quiescent radio source, suggests the possibility that frbs originate from magnetars, formed by the unusual supernovae that occur in such galaxies. we investigate this possibility via a comparison of magnetar birth rates, the frb volumetric rate, and host galaxy demographics. we calculate average volumetric rates of possible millisecond magnetar production channels, such as superluminous supernovae (slsne), long and short gamma-ray bursts (grbs), and general magnetar production via core-collapse supernovae (ccsne). for each channel, we also explore the expected host galaxy demographics using their known properties. we determine for the first time the number density of frb emitters (the product of their volumetric birth rate and lifetime), {r}{frb}τ ≈ {10}4 gpc-3, assuming that frbs are predominantly emitted from repetitive sources similar to frb 121102 and adopting a beaming factor of 0.1. by comparing rates, we find that production via rare channels (slsne, grbs) implies a typical frb lifetime of ∼30-300 years, in good agreement with other lines of argument. the total energy emitted over this time is consistent with the available energy stored in the magnetic field. on the other hand, any relation to magnetars produced via normal ccsne leads to a very short lifetime of ∼0.5 years, in conflict with both theory and observation. we demonstrate that due to the diverse host galaxy distributions of the different progenitor channels, many possible sources of frb birth can be ruled out with ≲ 10 host galaxy identifications. conversely, targeted searches of galaxies that have previously hosted decades-old slsne and grbs may be a fruitful strategy for discovering new frbs and related quiescent radio sources, and determining the nature of their progenitors. | empirical constraints on the origin of fast radio bursts: volumetric rates and host galaxy demographics as a test of millisecond magnetar connection |
gamma-ray bursts (grbs), as a possible probe to extend the hubble diagram to high redshifts, have attracted much attention recently. in this paper, we select two samples of grbs that have a plateau phase in x-ray afterglow. one is short grbs (sgrbs) with plateau phases dominated by magnetic dipole (md) radiations. the other is long grbs (lgrbs) with gravitational wave (gw) dominated plateau phases. these grbs can be well standardized using the correlation between the plateau luminosity l0 and the end time of plateau tb. the so-called circularity problem is mitigated by using the observational hubble parameter data and gaussian process method. the calibrated l0 - tb correlations are also used to constrain lambda cold dark matter (λcdm) and w(z) = w0 models. combining the md-lgrbs sample from wang et al. (2021) and the md-sgrbs sample, we find $\omega _{\mathrm{ m}} = 0.33_{-0.09}^{+0.06}$ and ωλ = $1.06_{-0.34}^{+0.15}$ excluding systematic uncertainties in the non-flat λcdm model. adding type ia supernovae from pantheon sample, the best-fitting results are w0 = $-1.11_{-0.15}^{+0.11}$ and ωm = $0.34_{-0.04}^{+0.05}$ in the w = w0 model. these results are in agreement with the λcdm model. our result supports that selection of grbs from the same physical mechanism is crucial for cosmological purposes. | measuring cosmological parameters with a luminosity-time correlation of gamma-ray bursts |
this research paper deals with a transit dark energy cosmological model in f(r,lm)-gravity with observational constraints. for this, we consider a flat friedman-lamatre-robertson-walker (flrw) space-time and have taken a cosmological constant-like parameter β in our field equations. the model has two energy parameters ωm0andωβ0, which govern the mechanism of the universe, in particular its present accelerated phase. to make the model cope with the present observational scenario, we consider three types of observational data set: 46 hubble parameter data set, sne ia 715 data sets of distance modulus and apparent magnitude, and 40 datasets of sne ia bined compilation in the redshift 0 ≤ z < 1.7. we have approximated the present values of the energy parameters by applying r2 and χ2-test in the observational and theoretical values of hubble, distance modulus and apparent magnitude parameters. also, we have measured the approximate present values of cosmographic coefficients {h0,q0,j0,s0,l0,m0}. it is found that our approximated value-based model fits best with the observational module. we have found that as t →∞ (or z → 0) then {q,j,s,l,m}→{−1, 1, 1, 1, 1}. the cosmic age of the present universe is also approximated and comes up to the expectation. our model shows a transit phase of the present accelerating universe with a deceleration in the past and has a transition point. | modeling transit dark energy in f(r,lm)-gravity |
we constrain spatially flat tilted and nonflat untilted scalar field (ϕ) dynamical dark energy inflation (ϕcdm) models by using planck 2015 cosmic microwave background (cmb) anisotropy measurements and recent baryonic acoustic oscillation distance observations, type ia supernovae apparent magnitude data, hubble parameter measurements, and growth rate data. we assume an inverse power-law scalar field potential energy density v(φ )={v}0{φ }-α . we find that the combination of the cmb data with the four non-cmb data sets significantly improves parameter constraints and strengthens the evidence for nonflatness in the nonflat untilted ϕcdm case from 1.8σ for the cmb measurements only to more than 3.1σ for the combined data. in the nonflat untilted ϕcdm model, current observations favor a spatially closed universe with spatial curvature contributing about two-thirds of a percent of the present cosmological energy budget. the flat tilted ϕcdm model is a 0.4σ better fit to the data than is the standard flat tilted λcdm model: current data allow for the possibility that dark energy is dynamical. the nonflat tilted ϕcdm model is in better accord with the dark energy survey bounds on the rms amplitude of mass fluctuations now (σ 8) as a function of the nonrelativistic matter density parameter now (ω m ) but it does not provide as good a fit to the larger-multipole planck 2015 cmb anisotropy data as does the standard flat tilted λcdm model. a few cosmological parameter value measurements differ significantly when determined using the tilted flat and the untilted nonflat ϕcdm models, including the cold dark matter density parameter and the reionization optical depth. | observational constraints on the tilted spatially flat and the untilted nonflat ϕcdm dynamical dark energy inflation models |
we propose a simple analytic model to understand when star formation is time steady versus bursty in galaxies. recent models explain the observed kennicutt-schmidt relation between star formation rate and gas surface densities in galaxies as resulting from a balance between stellar feedback and gravity. we argue that bursty star formation occurs when such an equilibrium cannot be stably sustained, and identify two regimes in which galaxy-scale star formation should be bursty: (i) at high redshift (z ≳ 1) for galaxies of all masses, and (ii) at low masses (depending on gas fraction) for galaxies at any redshift. at high redshift, characteristic galactic dynamical time-scales become too short for supernova feedback to effectively respond to gravitational collapse in galactic discs (an effect recently identified for galactic nuclei), whereas in dwarf galaxies star formation occurs in too few bright star-forming regions to effectively average out. burstiness is also enhanced at high redshift owing to elevated gas fractions in the early universe. our model can thus explain the bursty star formation rates predicted in these regimes by recent high-resolution galaxy formation simulations, as well as the bursty star formation histories observationally inferred in both local dwarf and high-redshift galaxies. in our model, bursty star formation is associated with particularly strong spatiotemporal clustering of supernovae. such clustering can promote the formation of galactic winds and our model may thus also explain the much higher wind mass loading factors inferred in high-redshift massive galaxies relative to their z ∼ 0 counterparts. | a model for the origin of bursty star formation in galaxies |
dark matter direct detection experiments have poor sensitivity to a galactic population of dark matter with mass below the gev scale. however, such dark matter can be produced copiously in supernovae. since this thermally produced population is much hotter than the galactic dark matter, it can be observed with direct detection experiments. in this paper, we focus on a dark sector with fermion dark matter and a heavy dark photon as a specific example. we first extend existing supernova cooling constraints on this model to the regime of strong coupling where the dark matter becomes diffusively trapped in the supernova. then, using the fact that even outside these cooling constraints the diffuse galactic flux of these dark sector particles can still be large, we show that this flux is detectable in direct detection experiments such as current and next-generation liquid xenon detectors. as a result, due to supernova production, light dark matter has the potential to be discovered over many orders of magnitude of mass and coupling. | supernova signals of light dark matter |
we present a sample of 21 hydrogen-free superluminous supernovae (slsne-i) and one hydrogen-rich slsn (slsn-ii) detected during the five-year dark energy survey (des). these sne, located in the redshift range 0.220 < z < 1.998, represent the largest homogeneously selected sample of slsn events at high redshift. we present the observed g, r, i, z light curves for these sne, which we interpolate using gaussian processes. the resulting light curves are analysed to determine the luminosity function of slsne-i, and their evolutionary time-scales. the des slsn-i sample significantly broadens the distribution of slsn-i light-curve properties when combined with existing samples from the literature. we fit a magnetar model to our slsne, and find that this model alone is unable to replicate the behaviour of many of the bolometric light curves. we search the des slsn-i light curves for the presence of initial peaks prior to the main light-curve peak. using a shock breakout model, our monte carlo search finds that 3 of our 14 events with pre-max data display such initial peaks. however, 10 events show no evidence for such peaks, in some cases down to an absolute magnitude of <-16, suggesting that such features are not ubiquitous to all slsn-i events. we also identify a red pre-peak feature within the light curve of one slsn, which is comparable to that observed within sn2018bsz. | superluminous supernovae from the dark energy survey |
we quantify the stellar abundances of neutron-rich r-process nuclei in cosmological zoom-in simulations of a milky way-mass galaxy from the feedback in realistic environments project. the galaxy is enriched with r-process elements by binary neutron star (ns) mergers and with iron and other metals by supernovae. these calculations include key hydrodynamic mixing processes not present in standard semi-analytic chemical evolution models, such as galactic winds and hydrodynamic flows associated with structure formation. we explore a range of models for the rate and delay time of ns mergers, intended to roughly bracket the wide range of models consistent with current observational constraints. we show that ns mergers can produce [r-process/fe] abundance ratios and scatter that appear reasonably consistent with observational constraints. at low metallicity, [fe/h] ≲ -2, we predict there is a wide range of stellar r-process abundance ratios, with both supersolar and subsolar abundances. low-metallicity stars or stars that are outliers in their r-process abundance ratios are, on average, formed at high redshift and located at large galactocentric radius. because ns mergers are rare, our results are not fully converged with respect to resolution, particularly at low metallicity. however, the uncertain rate and delay time distribution of ns mergers introduce an uncertainty in the r-process abundances comparable to that due to finite numerical resolution. overall, our results are consistent with ns mergers being the source of most of the r-process nuclei in the universe. | galactic r-process enrichment by neutron star mergers in cosmological simulations of a milky way-mass galaxy |
we present the first 4π-three-dimensional (3d) simulation of the last minutes of oxygen shell burning in an 18 m ⊙ supernova progenitor up to the onset of core collapse. a moving inner boundary is used to accurately model the contraction of the silicon and iron core according to a one-dimensional stellar evolution model with a self-consistent treatment of core deleptonization and nuclear quasi-equilibrium. the simulation covers the full solid angle to allow the emergence of large-scale convective modes. due to core contraction and the concomitant acceleration of nuclear burning, the convective mach number increases to ∼0.1 at collapse, and an ℓ = 2 mode emerges shortly before the end of the simulation. aside from a growth of the oxygen shell from 0.51 m ⊙ to 0.56 m ⊙ due to entrainment from the carbon shell, the convective flow is reasonably well described by mixing-length theory, and the dominant scales are compatible with estimates from linear stability analysis. we deduce that artificial changes in the physics, such as accelerated core contraction, can have precarious consequences for the state of convection at collapse. we argue that scaling laws for the convective velocities and eddy sizes furnish good estimates for the state of shell convection at collapse and develop a simple analytic theory for the impact of convective seed perturbations on shock revival in the ensuing supernova. we predict a reduction of the critical luminosity for explosion by 12%-24% due to seed asphericities for our 3d progenitor model relative to the case without large seed perturbations. | the last minutes of oxygen shell burning in a massive star |
the nature of the first pop iii stars is still a mystery and the energy distribution of the first supernovae is completely unexplored. for the first time we account simultaneously for the unknown initial mass function (imf), stellar mixing, and energy distribution function (edf) of pop iii stars in the context of a cosmological model for the formation of a mw-analogue. our data-calibrated semi-analytic model is based on a n-body simulation and follows the formation and evolution of both pop iii and pop ii/i stars in their proper time-scales. we discover degeneracies between the adopted pop iii unknowns, in the predicted metallicity and carbonicity distribution functions and the fraction of c-enhanced stars. none the less, we are able to provide the first available constraints on the edf, $dn/de_\star \propto e_{\star }^{-\alpha _e}$ with 1 ≤ αe ≤ 2.5. in addition, the characteristic mass of the pop iii imf should be mch < 100 m⊙, assuming a mass range consistent with hydrodynamical simulations (0.1-1000 m⊙). independent of the assumed pop iii properties, we find that all $\rm [c/fe]\gt +0.7$ stars (with $\rm [fe/h]\lt -2.8$) have been enriched by pop iii supernovae at a $\gt 20~{{\ \rm per\ cent}}$ level, and all $\rm [c/fe]\gt +2$ stars at a $\gt 95~{{\ \rm per\ cent}}$ level. all very metal-poor stars with $\rm [c/fe]\lt 0$ are predicted to be predominantly enriched by pop iii hypernovae and/or pair instability supernovae. to better constrain the primordial edf, it is absolutely crucial to have a complete and accurate determination of the metallicity distribution function, and the properties of c-enhanced metal-poor stars (frequency and [c/fe]) in the galactic halo. | the energy distribution of the first supernovae |
cosmological analyses with type ia supernovae (sne ia) often assume a single empirical relation between colour and luminosity (β) and do not account for varying host-galaxy dust properties. however, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. here, we take advantage of state-of-the-art modelling of galaxy properties to characterize dust parameters (dust attenuation av, and a parameter describing the dust law slope rv) for 1100 dark energy survey (des) sn host galaxies. utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact sn cosmology: (1) there exists a large range (~1-6) of host rv; (2) high-stellar mass hosts have rv on average ~0.7 lower than that of low-mass hosts; (3) for a subsample of 81 spectroscopically classified sne there is a significant (>3σ) correlation between the hubble diagram residuals of red sne ia and the host rv that when corrected for reduces scatter by $\sim 13{{\ \rm per\ cent}}$ and the significance of the 'mass step' to ~1σ. these represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling 'mass step' and intrinsic scatter (σint) in sn ia analyses. | the dark energy survey supernova program results: type ia supernova brightness correlates with host galaxy dust |
in recent years, several analytic models have demonstrated that simple assumptions about halo growth and feedback-regulated star formation can match the (limited) existing observational data on galaxies at $z \gtrsim6$. by extending such models, we demonstrate that imposing a time delay on stellar feedback (as inevitably occurs in the case of supernova explosions) induces burstiness in small galaxies. although supernova progenitors have short lifetimes (~5-30 myr), the delay exceeds the dynamical time of galaxies at such high redshifts. as a result, star formation proceeds unimpeded by feedback for several cycles and 'overshoots' the expectations of feedback-regulated star formation models. we show that such overshoot is expected even in atomic cooling haloes, with halo masses up to ~1010.5 m⊙ at z ≳ 6. however, these burst cycles damp out quickly in massive galaxies, because large haloes are more resistant to feedback so retain a continuous gas supply. bursts in small galaxies - largely beyond the reach of existing observations - induce a scatter in the luminosity of these haloes (of ~1 mag) and increase the time-averaged star formation efficiency by up to an order of magnitude. this kind of burstiness can have substantial effects on the earliest phases of star formation and reionization. | bursty star formation during the cosmic dawn driven by delayed stellar feedback |
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