Constraining of Nuclear Matter Equations of State With Rotating Neutron Stars

TL;DR

This paper uses the KEH method to model rapidly rotating neutron stars with various equations of state, demonstrating how rotation affects their mass-radius relation and emphasizing the need to include rotational effects in astrophysical analyses.

Contribution

It presents the first application of the KEH method to Gogny-type EoSs for rotating neutron stars, highlighting the impact of rotation on their structural properties.

Findings

Mass-radius relation varies with angular velocity

Rotational effects significantly alter neutron star structure

Including rotation is crucial for matching observations

Abstract

Neutron stars can be regarded as natural laboratories that enable us to investigate nuclear matter properties under extreme conditions that are otherwise impossible to access in terrestrial experiments. Astrophysical observations of neutron stars provide invaluable information on existing nuclear interaction models and equations of state (EoSs) at various densities. Most studies of neutron star structure employ the Tolman-Oppenheimer-Volkoff (TOV) equation which describes spherically symmetric, non-rotating stars in hydrostatic equilibrium. However, since neutron stars rotate fast, they could experience significant centrifugal deformation, and axially-symmetric calculations are required for accurate description of internal structure. The Komatsu-Eriguchi-Hachisu (KEH) method is well known for modeling rapidly-rotating compact objects in a fully general relativistic manner. In this contribution, we report results of KEH calculations for rapidly-rotating neutron stars using EoSs based on Gogny-type finite-range effective nucleon-nucleon interactions. Our results show that the mass-radius relation systematically changes with increasing angular velocity, highlighting the importance of including rotational effects when confronting theoretical EoSs with observational data.