Modeling neutrino effects on multimessenger GW sources in numerical relativity simulations

Compact objects can produce the most luminous events in the universe by being sources of both gravitational and electromagnetic waves. For multimessenger sources, where significant amounts of matter are present, the energies and densities typically make neutrino-driven cooling and feedback important to the overall dynamics. Accurately simulating neutrino effects for general relativistic systems is therefore widely recognized to be a necessity in the quest to arrive at more precise multimessenger source models. In particular, neutrino transport is known to be crucial for any quantitatively precise modeling of the post-merger evolution of binary neutron star mergers like GW170817. Additionally, disk cooling driven by neutrinos is potentially a crucially important effect that, if sufficiently rapid, may allow some accretion disks (such as those of collapsar remnants) to sustain instabilities producing detectable gravitational wave emission. We have developed and applied novel numerical relativity codes to these systems to investigate the impact of neutrinos in full dynamical spacetime simulations. Our new numerical methods will be described in detail, and preliminary results will be presented.