Neutron star equations of state with optical potential constraint

TL;DR

This paper develops an extended relativistic mean-field model for nuclear matter and neutron stars, incorporating optical potential constraints, leading to softer equations of state and lower maximum neutron star masses.

Contribution

It introduces new RMF parametrisations with derivative couplings constrained by optical potential data, improving the modeling of neutron star equations of state.

Findings

Optical potential constraints soften the EoS.

Maximum neutron star mass is reduced with these constraints.

Multiple parametrisations consistent with nuclear saturation properties.

Abstract

Nuclear matter and neutron stars are studied in the framework of an extended relativistic mean-field (RMF) model with higher-order derivative and density dependent couplings of nucleons to the meson fields. The derivative couplings lead to an energy dependence of the scalar and vector self-energies of the nucleons. It can be adjusted to be consistent with experimental results for the optical potential in nuclear matter. Several parametrisations, which give identical predictions for the saturation properties of nuclear matter, are presented for different forms of the derivative coupling functions. The stellar structure of spherical, non-rotating stars is calculated for these new equations of state (EoS). A substantial softening of the EoS and a reduction of the maximum mass of neutron stars is found if the optical potential constraint is satisfied.