Symmetry energy of super-dense neutron-rich matter from integrating barotropic pressures in neutron stars and heavy-ion reactions

TL;DR

This paper introduces a new method to determine the symmetry energy of super-dense neutron-rich matter by integrating barotropic pressures from neutron stars and heavy-ion reactions, providing constraints above twice nuclear saturation density.

Contribution

A novel approach to infer symmetry energy directly from pressure integration in neutron stars and heavy-ion collisions, linking astrophysical and nuclear experimental data.

Findings

Constrains symmetry energy above 2ρ₀ using GW170817 data.

Extracts proton fraction at β equilibrium as a function of density.

Provides a constraining band for symmetry energy at high densities.

Abstract

Within the minimum model of neutron stars (NS) consisting of neutrons, protons and electrons, a new approach is proposed for inferring the symmetry energy of super-dense neutron-rich nucleonic matter above twice the saturation density $\rho_0$ of nuclear matter directly from integrating iteratively barotropic pressures in both neutron stars and heavy-ion reactions. Simultaneously, the proton fraction of NSs at $\beta$ equilibrium is extracted as a function of baryon density from the same procedure. An application of this approach using the NS pressure from GW170817 and the pressure in cold symmetric nuclear matter (SNM) extracted earlier by analyzing nuclear collective flow data in relativistic heavy-ion collisions provides a useful constraining band for the symmetry energy above $2\rho_0$.