@article{johnston_wasik_titus_warren_evan p. o'connor_zegers_couch_2022, title={Comparison of Electron Capture Rates in the N=50 Region using 1D Simulations of Core-collapse Supernovae}, volume={939}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/ac9306}, abstractNote={Abstract
               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 parametrized 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.}, number={1}, journal={ASTROPHYSICAL JOURNAL}, author={Johnston, Zac and Wasik, Sheldon and Titus, Rachel and Warren, MacKenzie L. and Evan P. O'Connor and Zegers, Remco and Couch, Sean M.}, year={2022}, month={Nov} }
 @article{myers_cooper_warren_kneller_mclaughlin_richers_grohs_frohlich_2022, title={Neutrino flavor mixing with moments}, volume={105}, ISSN={["2470-0029"]}, url={https://doi.org/10.1103/PhysRevD.105.123036}, DOI={10.1103/PhysRevD.105.123036}, abstractNote={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.}, number={12}, journal={PHYSICAL REVIEW D}, author={Myers, McKenzie and Cooper, Theo and Warren, MacKenzie and Kneller, Jim and McLaughlin, Gail and Richers, Sherwood and Grohs, Evan and Frohlich, Carla}, year={2022}, month={Jun} }
 @article{pajkos_warren_couch_evan p. o'connor_pan_2021, title={Determining the Structure of Rotating Massive Stellar Cores with Gravitational Waves}, volume={914}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/abfb65}, abstractNote={Abstract
               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 neutrino-radiation-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.}, number={2}, journal={ASTROPHYSICAL JOURNAL}, author={Pajkos, Michael A. and Warren, MacKenzie L. and Couch, Sean M. and Evan P. O'Connor and Pan, Kuo-Chuan}, year={2021}, month={Jun} }
 @article{warren_couch_evan p. o'connor_morozova_2020, title={Constraining Properties of the Next Nearby Core-collapse Supernova with Multimessenger Signals}, volume={898}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/ab97b7}, abstractNote={Abstract
               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.}, number={2}, journal={ASTROPHYSICAL JOURNAL}, author={Warren, MacKenzie L. and Couch, Sean M. and Evan P. O'Connor and Morozova, Viktoriya}, year={2020}, month={Aug} }
 @article{hermansen_couch_roberts_schatz_warren_2020, title={Reaction Rate Sensitivity of the Production of gamma-Ray Emitting Isotopes in Core-collapse Supernovae}, volume={901}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/abafb5}, abstractNote={Abstract
               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 γ-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
                  ⊙ ejecta from the core collapse and explosion of a 12 M
                  ⊙ star. Individually varying 3403 reaction rates by factors of 100, we identify 141 reactions that cause significant differences in the isotopes of interest, namely, 43K, 47Ca, 44,47Sc, 44Ti, 48,51Cr, 48,49V, 52,53Mn, 55,59Fe, 56,57Co, and 56,57,59Ni. 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 = 0.47–6.15 GK. Limiting the variations to within 1σ 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.}, number={1}, journal={ASTROPHYSICAL JOURNAL}, author={Hermansen, Kirby and Couch, Sean M. and Roberts, Luke F. and Schatz, Hendrik and Warren, MacKenzie L.}, year={2020}, month={Sep} }