Abstract
We have conducted a series of numerical experiments using spherically symmetric, general relativistic, neutrino radiation hydrodynamics with the code Agile-BOLTZTRAN to examine the effects of including, and improving, the calculation of neutrino opacities on the development of supernova simulations by removing, or replacing, each opacity individually, or removing opacities in groups.
We find that during core collapse improvements to electron capture (EC) on nuclei, namely EC on an ensemble of nuclei based on the hybrid model, relative to the simpler independent-particle approximation (IPA) for a mean nucleus, plays the most important role of all tested neutrino opacities.
Low-energy neutrinos emitted by nuclear EC preferentially escape during collapse leading to larger deleptonization of the collapsing core, without the energy downscattering via non-isoenergetic scattering (NIS) on electrons required for the models with IPA nuclear EC.
During shock breakout the primary influence on the emergent neutrinos arises from NIS on electrons.
For the accretion phase NIS on free nucleons and pair emission by $e^+e^-$-annihilation have the largest impact on the neutrino emission and shock evolution.
Other opacities evaluated including nucleon-nucleon bremsstrahlung and especially neutrino-positron scattering have little measurable impact on neutrino emission or shock dynamics.
Modern treatments of nuclear electron capture, $e^+e^-$-annihilation pair emission, and non-isoenergetic scattering on electrons and free nucleons are critical elements of core-collapse simulations of all dimensionality.
