Talks and Posters

Contributed Talks

Neutrino-Matter Interactions in Neutron Star Merger Simulations

[05/2019] FOE2019

Neutrinos play an important role in the nucleosynthesis, post-merger evolution, and electromagnetic transients produced in binary neutron star mergers. To reliably model these effects, we need accurate neutrino transport in merger simulations. However, it is prohibitively expensive to evolve the Boltzmann transport equation directly and simulations rely on various approximate methods instead. In order to understand how to interpret simulation results, we need to understand the errors associated with approximate transport schemes. To this end, we use the time-independent Monte Carlo neutrino transport code Sedonu to calculate the neutrino distribution function, along with the heating, leptonization and neutrino pair-annihilation rates, for a number of post-merger snapshots. The snapshots are taken from dynamical merger simulations with M0 transport, spanning a range of binary mass ratios, equations of state and merger outcomes. In this talk, I identify the major discrepancies between our results and those obtained with M0 transport for the same set of weak reactions. I then present our full calculations that include, for the first time, the effects of inelastic neutrino-electron scattering in the merger case. Finally, I discuss the implications of our results for the treatment of neutrinos in future dynamical simulations.

PUSHing Core-Collapse Supernovae to Explosions in Spherical Symmetry: Nucleosynthesis Yields

[01/2017] APS2017
[06/2017] FOE2017

Core-collapse supernovae (CCSNe) are highly energetic events that mark the deaths of massive stars. They play a vital role in the synthesis and dissemination of many chemical elements in the universe. Here, we present the results of a nucleosynthesis study of multiple progenitors exploded using the PUSH method. The explodability and explosion properties obtained with PUSH are discussed in detail in K. Ebinger's contribution. PUSH is a robust parametrized method, calibrated using observed nearby SNe. It predicts crucial nucleosynthesis related quantities, such as the mass cut, and follows the electron fraction evolution of the ejecta. This allows a more accurate treatment of nucleosynthesis in the innermost stellar layers, in contrast with previous studies that relied on externally imposed values instead of predictions. In this study, we include models spanning a wide mass range and find trends relating the iron-group and alpha element yields to progenitor compactness. We also present comparisons of the calculated iron group yields to observational data from supernovae and metal-poor stars. These complete and comprehensive nucleosynthesis predictions are an important input for models of galactic chemical evolution.