Equation of state of asymmetric nuclear matter and the tidal deformability of neutron star

TL;DR

This paper models the equation of state of asymmetric nuclear matter using a mean-field approach to understand neutron star properties and their tidal deformability, comparing results with gravitational wave observations from GW170817.

Contribution

It introduces a nonrelativistic Hartree-Fock mean-field model to derive the EOS of neutron star matter and assesses its impact on tidal deformability and mass-radius relations.

Findings

Incompressibility of nuclear matter significantly affects neutron star structure.

Model results are consistent with GW170817 observational constraints.

Tidal deformability is sensitive to the nuclear matter EOS.

Abstract

Neutron star (NS) is a unique astronomical compact object where the four fundamental interactions have been revealed from the observation and studied in different ways. While the macroscopic properties of NS like mass and radius can be determined within the General Relativity using a realistic equation of state (EOS) of NS matter, such an EOS is usually generated by a nuclear structure model like, e.g., the nuclear mean-field approach to asymmetric nuclear matter. Given the radius of NS extended to above 10 km and its mass up to twice the solar mass, NS is expected to be tidally deformed when it is embedded in a strong tidal field. Such a tidal effect was confirmed unambiguously in the gravitation wave signals detected recently by the LIGO and Virgo laser interferometers from GW170817, the first ever direct observation of a binary NS merger. A nonrelativistic mean-field study is carried out in the present work within the Hartree-Fock formalism to construct the EOS of NS matter, which is then used to determine the tidal deformability, gravitational mass, and radius of NS. The mean-field results are compared with the constraints imposed for these quantities by the global analysis of the observed GW170817 data, and a strong impact by the incompressibility of nuclear matter on the hydrostatic configuration of NS is shown.