Tables of Hyperonic Matter Equation of State for Core-Collapse Supernovae

TL;DR

This paper develops comprehensive equations of state including hyperons for core-collapse supernova simulations, showing how hyperons influence neutron star masses and are minimally impactful during early collapse phases.

Contribution

It introduces a new set of hyperonic EOS models based on an extended RMF framework with updated hyperon potentials, covering a wide range of conditions for supernova modeling.

Findings

Hyperons reduce maximum neutron star mass from 2.17 to 1.63 solar masses.

Hyperon effects are minimal during early supernova collapse phases.

EOS models connect with existing nuclear matter EOS at low densities.

Abstract

We present sets of equation of state (EOS) of nuclear matter including hyperons using an SU_f(3) extended relativistic mean field (RMF) model with a wide coverage of density, temperature, and charge fraction for numerical simulations of core collapse supernovae. Coupling constants of Sigma and Xi hyperons with the sigma meson are determined to fit the hyperon potential depths in nuclear matter, U_Sigma(rho_0) ~ +30 MeV and U_Xi(rho_0) ~ -15 MeV, which are suggested from recent analyses of hyperon production reactions. At low densities, the EOS of uniform matter is connected with the EOS by Shen et al., in which formation of finite nuclei is included in the Thomas-Fermi approximation. In the present EOS, the maximum mass of neutron stars decreases from 2.17 M_sun (Ne mu) to 1.63 M_sun (NYe mu) when hyperons are included. In a spherical, adiabatic collapse of a 15$M_\odot$ star by the hydrodynamics without neutrino transfer, hyperon effects are found to be small, since the temperature and density do not reach the region of hyperon mixture, where the hyperon fraction is above 1 % (T > 40 MeV or rho_B > 0.4 fm^{-3}).