General relativistic neutrino transport implemented using the two-moment method

Core Collapse Supernovae (CCSNe) occur when massive stars are at the end of their life cycles, and it has been shown that neutrinos play a pivotal role in the death-throes of these stars. CCSNe are known to be laboratories to study the creation of many of the heavier elements, the formation of black holes and neutron stars, and production of gravitational waves. To model CCSNe, we use a 3+1 formulation of general relativity along with general relativistic hydrodynamics and a general relativistic two-moment approach for neutrino transport, which is what we focus on here. We solve the transport equations numerically using the discontinuous-Galerkin method to discretize the equations in phase-space, because it is scalable, high-order accurate, and asymptotic preserving, and implicit-explicit time integration, because we must solve the neutrino-matter coupling problem implicitly. We will discuss these methods and show results from test problems for the neutrino sector of the model, specifically the so-called general relativistic homogeneous sphere problem, which tests the general relativistic properties of the code, and relaxation problems, which uses tabulated opacities and non-linear solves, to test the coupling of the neutrino and matter equations.