Thermal Index of Neutron Stars in the Virial Approximation

Abstract

In the era of gravitational waves detection, the need to understand matter at finite temperature has arisen. The thermal index describes the thermal effects in a neutron star’s equation of state. In this work we use the virial equation of state of interacting nucleons and consider the contributionof electrons as an ideal Fermi gas. We compute the thermal index for neutron stars in conditions oflow density and high temperature. We find that the thermal index ranges from 4/3 to 5/3, and is primarily sensitive to the isospin asymmetry of the system