Neutrinos in Neutron Star Merger Simulations

Francois Foucart (University of New Hampshire)

April 03, 2023

–

Abstract: Mergers of compact objects such as black holes and neutron stars have recently risen as remarkable astrophysical laboratories to test the laws of physics in extreme environments. From the gravitational waves and electromagnetic signals produced by these events, we can learn about the unknown properties of dense neutron rich matter, study the laws of gravity and the expansion of the Universe, or attempt to constrain the origin of the heavy nuclei observed on Earth today. Neutron star mergers are however complex non-linear systems that can only be truly understood through costly numerical simulations modeling general relativity, relativistic magnetohydrodynamics, neutrino transport, and maybe even out-of-equilibrium nuclear reaction. In this talk, I will provide a brief overview of the physics of these mergers and of our understanding of the matter outflows that they produce. I will then discuss the particular problem of general relativistic neutrino transport, and how modern simulations attempt to solve the high-dimensional equations of radiation transport at a reasonable computational cost.