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Recent studies have highlighted the sensitivity of core-collapse supernovae (CCSNe) models to electron-capture (EC) rates on neutron-rich nuclei near the N=50 closed-shell region. In this work, we perform a large suite of one-dimensional CCSN simulations for 200 stellar progenitors using recently updated EC rates in this region. For comparison, we repeat the simulations using two previous implementations of EC rates: a microphysical library with parameterized N=50 rates (LMP), and an older independent-particle approximation (IPA). We follow the simulations through shock revival up to several seconds post-bounce, and show that the EC rates produce a consistent imprint on CCSN properties, often surpassing the role of the progenitor itself. Notable impacts include the timescale of core collapse, the electron fraction and mass of the inner core at bounce, the accretion rate through the shock, the success or failure of revival, and the properties of the central compact remnant. We also compare the observable neutrino signal of the neutronization burst in a DUNE-like detector, and find consistent impacts on the counts and mean energies. Overall, the updated rates result in properties that are intermediate between LMP and IPA, and yet slightly more favorable to explosion than both., Comment: 14 pages, 8 figures, 1 table. Updated Fig 5, minor corrections, renamed SNA to IPA. Accepted by ApJ

The successful transition from core-collapse supernova simulations using classical neutrino transport to simulations using quantum neutrino transport will require the development of methods for calculating neutrino flavor transformations that mitigate the computational expense. One potential approach is the use of angular moments of the neutrino field, which has the added appeal that there already exist simulation codes which make use of moments for classical neutrino transport. Evolution equations for quantum moments based on the quantum kinetic equations can be straightforwardly generalized from the evolution of classical moments based on the Boltzmann equation. We present an efficient implementation of neutrino transformation using quantum angular moments in the free streaming, spherically symmetric bulb model. We compare the results against analytic solutions and the results from more exact multi-angle neutrino flavor evolution calculations. We find that our moment-based methods employing scalar closures predict, with good accuracy, the onset of collective flavor transformations seen in the multi-angle results. However in some situations they overestimate the coherence of neutrinos traveling along different trajectories. More sophisticated quantum closures may improve the agreement between the inexpensive moment-based methods and the multi-angle approach., Comment: Accepted in Physical Review D

Observations of core-collapse supernovae (CCSNe) reveal a wealth of information about the dynamics of the supernova ejecta and its composition but very little direct information about the progenitor. Constraining properties of the progenitor and the explosion requires coupling the observations with a theoretical model of the explosion. Here, we begin with the CCSN simulations of Couch et al 2020 ApJ 890 127, which use a non-parametric treatment of the neutrino transport while also accounting for turbulence and convection. In this work we use the SuperNova Explosion Code to evolve the CCSN hydrodynamics to later times and compute bolometric light curves. Focusing on SNe IIP, we then (1) directly compare the theoretical STIR explosions to observations and (2) assess how properties of the progenitor's core can be estimated from optical photometry in the plateau phase alone. First, the distribution of plateau luminosities (L$_{50}$) and ejecta velocities achieved by our simulations is similar to the observed distributions. Second, we fit our models to the light curves and velocity evolution of some well-observed SNe. Third, we recover well-known correlations, as well as the difficulty of connecting any one SN property to zero-age main sequence mass. Finally, we show that there is a usable, linear correlation between iron core mass and L$_{50}$ such that optical photometry alone of SNe IIP can give us insights into the cores of massive stars. Illustrating this by application to a few SNe, we find iron core masses of 1.3-1.5 solar masses with typical errors of ~0.05 solar masses. Data are publicly available online (\url{https://doi.org/10.5281/zenodo.6631964})., Comment: 23 pages, Accepted to ApJ. Data available online https://doi.org/10.5281/zenodo.6631964

The gravitational wave (GW) signal resulting from stellar core collapse encodes a wealth of information about the physical parameters of the progenitor star and the resulting core-collapse supernova (CCSN). We present a novel approach to constrain CCSN progenitor properties at collapse using two of the most detectable parts of the GW signal: the core-bounce signal and evolution of the dominant frequency mode from the protoneutron star. We focus on the period after core bounce but before explosion and investigate the predictive power of GWs from rotating CCSNe to constrain properties of the progenitor star. We analyze 34 2D and four 3D neutrinoradiation-hydrodynamic simulations of stellar core collapse in progenitors of varied initial mass and rotation rate. Extending previous work, we verify the compactness of the progenitor at collapse to correlate with the early ramp-up slope, and in rotating cases, also with the core angular momentum. Combining this information with the bounce signal, we present a new analysis method to constrain the pre-collapse core compactness of the progenitor. Because these GW features occur less than a second after core bounce, this analysis could allow astronomers to predict electromagnetic properties of a resulting CCSN even before shock breakout., Comment: 21 pages, 11 figures; Published in ApJ

Radioactive isotopes produced in core-collapse supernovae (CCSNe) provide useful insights into the underlying processes driving the collapse mechanism and the origins of elemental abundances. Their study generates a confluence of major physics research, including experimental measurements of nuclear reaction rates, astrophysical modeling, and $\gamma$-ray observations. Here we identify the key nuclear reaction rates to the nucleosynthesis of observable radioactive isotopes in explosive silicon-burning during CCSNe. Using the nuclear reaction network calculator SkyNet and current REACLIB reaction rates, we evolve temperature-density-time profiles of the innermost $0.45~M_\odot$ ejecta from the core collapse and explosion of a $12~M_\odot$ star. Individually varying 3403 reaction rates by factors of 100, we identify 141 reactions which cause significant differences in the isotopes of interest, namely, $^{43}$K, $^{47}$Ca, $^{44,47}$Sc, $^{44}$Ti, $^{48,51}$Cr, $^{48,49}$V, $^{52,53}$Mn, $^{55,59}$Fe, $^{56,57}$Co, and $^{56,57,59}$Ni. For each of these reactions, we present a novel method to extract the temperature range pertinent to the nucleosynthesis of the relevant isotope; the resulting temperatures lie within the range $T = 0.47$ to $6.15~$GK. Limiting the variations to within $1\sigma$ of STARLIB reaction rate uncertainties further reduces the identified reactions to 48 key rates, which can be used to guide future experimental research. Complete results are presented in tabular form., Comment: 18 pages, 6 figures, 3 tables, Accepted by The Astrophysical Journal

With the advent of modern neutrino and gravitational wave detectors, the promise of multi-messenger detections of the next galactic core-collapse supernova has become very real. Such detections will give insight into the core-collapse supernova mechanism, 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 core-collapse supernova events, and their multi-messenger signals, is needed. We present detailed predictions of neutrino and gravitational wave signals from 1D simulations of stellar core collapse, spanning the landscape of core-collapse progenitors from $9-120\,\mathrm{M}_{\odot}$. In order to achieve explosions in 1D, we use the STIR model, which includes the effects of turbulence and convection in 1D supernova simulations to mimic the 3D explosion mechanism. We study the gravitational wave emission from the 1D simulations using an astroseismology analysis of the proto-neutron star. We find that the neutrino and gravitational wave 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 gravitational wave emission from a galactic core-collapse supernova may be able to provide constraints on stellar evolution independent of pre-explosion imaging and the mass of the compact object remnant prior to fallback accretion., Comment: 25 pages, 15 figures, 8 tables, 462 explosions, 2.7e6 neutrinos. Submitted to AAS Journals

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions., Comment: 14 pages including 3 figures

The core-collapse supernova (CCSN) mechanism is fundamentally three-dimensional with instabilities, convection, and turbulence playing crucial roles in aiding neutrino-driven explosions. Simulations of CCNSe including accurate treatments of neutrino transport and sufficient resolution to capture key instabilities remain amongst the most expensive numerical simulations in astrophysics, prohibiting large parameter studies in 2D and 3D. Studies spanning a large swath of the incredibly varied initial conditions of CCSNe are possible in 1D, though such simulations must be artificially driven to explode. We present a new method for including the most important effects of convection and turbulence in 1D simulations of neutrino-driven CCSNe, called Supernova Turbulence In Reduced-dimensionality, or STIR. Our new approach includes crucial terms resulting from the turbulent and convective motions of the flow. We estimate the strength of convection and turbulence using a modified mixing length theory (MLT) approach introducing a few free parameters to the model which are fit to the results of 3D simulations. For sufficiently large values of the mixing length parameter, turbulence-aided neutrino-driven explosions are obtained. We compare the results of STIR to high-fidelity 3D simulations and perform a parameter study of CCSN explosion using 200 solar-metallicity progenitor models from 9 to 120 $M_\odot$. We find that STIR is a better predictor of which models will explode in multidimensional simulations than other methods of driving explosions in 1D. We also present a preliminary investigation of predicted observable characteristics of the CCSN population from STIR, such as the distributions of explosion energies and remnant masses., Comment: 30 pages, 17 figures. Substantially updated following referee report and resubmitted to AAS Journals

We present an updated general purpose nuclear equation of state (EoS) for use in simulations of core-collapse supernovae, neutron star mergers and black hole collapse. This EoS is formulated in the context of Density Functional Theory (DFT) and is generalized to include all DFT EoSs consistent with known nuclear and astrophysical constraints. This EoS also allows for the possibility of the formation of material with a net proton excess ($Y_p > 0.5$) and has an improved treatment of the nuclear statistical equilibrium and the transition to heavy nuclei as the density approaches nuclear matter density. We include the effects of pions in the regime above nuclear matter density and incorporate all of the known mesonic and baryonic states at high temperature. We analyze how a 3-body nuclear force term in the DFT at high densities stiffens the EoS to satisfy the maximum neutron star constraint, however the density dependence of the symmetry anergy and the formation of pions at high temperatures allows for a softening of the central core in supernova collapse calculations leading to a robust explosion. We also add the possibility of a transition to a QCD chiral-symmetry-restoration and deconfinement phase at densities above nuclear matter density. This paper details the physics, and constraints on, this new EoS and presents an illustration of its implementation in both neutron stars and core-collapse supernova simulations. We present the first results from core-collapse supernova simulations with this EoS., Comment: Submitted to Physical Review C. arXiv admin note: substantial text overlap with arXiv:1303.0064

We have explored the impact of sterile neutrino dark matter on core-collapse supernova explosions. We have included oscillations between electron neutrinos or mixed $\mu,\tau$ neutrinos and right-handed sterile neutrinos into a supernova model. We have chosen sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent x-ray flux measurements. Using these simulations, we have explored the impact of sterile neutrinos on the core bounce and shock reheating. We find that, for ranges of sterile neutrino mass and mixing angle consistent with most dark matter constraints, the shock energy can be significantly enhanced and even a model that does not explode can be made to explode. In addition, we have found that the presence of a sterile neutrino may lead to detectable changes in the observed neutrino luminosities.

We summarize the impact of sterile neutrino dark matter on core-collapse supernova explosions. We explore various oscillations between electron neutrinos or mixed $\mu-\tau$ neutrinos and right-handed sterile neutrinos that may occur within a core-collapse supernova. In particular, we consider sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent X-ray flux measurements. We find that the interpretation of the observed 3.5 keV X-ray excess as due to a decaying 7 keV sterile neutrino that comprises 100\% of the dark matter would have almost no observable effect on supernova explosions. However, in the more realistic case in which the decaying sterile neutrino comprises only a small fraction of the total dark matter density due to the presence of other sterile neutrino flavors, WIMPs, etc., a larger mixing angle is allowed. In this case a 7 keV sterile neutrino could have a significant impact on core-collapse supernovae. We also consider mixing between $\mu-\tau$ neutrinos and sterile neutrinos. We find, however, that this mixing does not significantly alter the explosion and has no observable effect on the neutrino luminosities at early times., Comment: 18 pages, 6 figures, submitted to Modern Physics Letters A

We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their anti particles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron anti-neutrinos from the core to behind the shock where they provide additional heating leading to much larger explosion kinetic energies. We show that this effect can cause stars to explode that otherwise would have collapsed. We find that an interesting periodicity in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core.