Effects of Different Closure Choices in Core-collapse Supernova Simulations

The two-moment method is widely used to approximate the full neutrino transport equation in core-collapse supernova (CCSN) simulations, and different closures lead to subtle differences in the simulation results. In this paper, we compare the effects of closure choices on various physical quantities in 1D and 2D time-dependent CCSN simulations with our multigroup radiation hydrodynamics code FORNAX. We find that choices of the third-order closure relations influence the time-dependent simulations only slightly. Choices of the second-order closure relation have larger consequences than choices of the third-order closure, but these are still small compared to the remaining variations due to ambiguities in some physical inputs such as the nuclear equation of state. We also find that deviations in Eddington factors are not monotonically related to deviations in physical quantities, which means that simply comparing the Eddington factors does not inform one concerning which closure is better.

Automated summary

In this paper, the effects of closure choices on various physical quantities in 1D and 2D time-dependent core-collapse supernova simulations are compared using the multigroup radiation hydrodynamics code FORNAX. It is found that the third-order closure relations have only slight influence on the time-dependent simulations. The second-order closure relation choices have larger consequences, but these are still small compared to other variations due to uncertainties in some physical inputs.