Recent neutron star simulations with the Nmesh Program

We present our recent simulations for single neutron star cases with the Nmesh program. We perform the evolutions with a combined finite volume (FV) method and discontinuous Galerkin method (DG), where we selectively use the DG method in grid domains with smooth matter fields and use the FV scheme in the domains with non-smooth matter fields. We introduce a new criterion for determining the smoothness and whether to utilize FV or DG in a domain. We evolve three single neutron star initial data for testing the performance of this new smoothness indicator: a stable neutron star, a highly dense unstable neutron star that migrates to a stable state, and a boosted neutron star. We compare the results with the combined DG+FV evolutions with our prior criteria for switching between FV and DG and the results from evolution with pure FV. We utilize the generalized harmonic evolution method to evolve the metric. We also include other mechanisms related to the matter fields, such as positivity limiters and an artificial atmosphere.