Simulating neutron stars with flexible equation of state parametrizations in SpECTRE

Numerical simulations of neutron star mergers are an important step in using multimessenger observations to constrain the properties of dense matter, however, such simulations are limited by the details of matter representation. We introduce a new parametrization of the dense nuclear equation of state which allows for fast, smooth approximation of hadronic models while maintaining flexibility for representing matter with phase transitions. We test the parametrization by simulating isolated neutron stars in the SpECTRE code. For low-precision modeling, we find robust fitting with little to no performance degradation relative to lower-parameter representations. At higher precision, necessary for capturing potential phase transitions, we find the new parametrization allows for evolution using arbitrary equations of state with modeling error in neutron star radii of 10 meters or less.