Investigating the role of nuclear parameters on oscillation modes in hot Neutron Stars

TL;DR

This study systematically examines how nuclear parameters and thermal effects influence the oscillation modes of hot neutron stars within a relativistic framework, highlighting the dominant role of the effective nucleon mass and the insensitivity of universal relations to nuclear saturation properties.

Contribution

It provides a comprehensive analysis of nuclear and thermal influences on neutron star oscillations, incorporating constraints from experiments and astrophysical data within a relativistic model.

Findings

Effective nucleon mass is the key nuclear parameter affecting hot neutron star observables.

Universal relations in gravitational wave asteroseismology are largely unaffected by nuclear saturation properties.

Thermal effects and constraints significantly influence the interplay of nuclear parameters and neutron star characteristics.

Abstract

Recent studies have revealed that certain nuclear parameters are more dominant than others in governing global neutron star properties, such as its structure or oscillation mode characteristics. Although neutron stars can in general assumed to be cold, in astrophysical scenarios such as newly born neutron stars or remnants of binary neutron star mergers, finite temperature effects play a non-negligible role. In this work, we perform a consistent and systematic investigation of the role of nuclear parameters and thermal effects on neutron star properties and fluid oscillation modes within a full general relativistic scheme. We impose constraints on the parameter space of the relativistic mean field model using state-of-the-art information from terrestrial experiments and multi-messenger astrophysical data. We find effective nucleon mass to be the most important nuclear parameter controlling astrophysical observables of hot neutron stars, similar to the cold beta equilibrated matter. However, we conclude that the interplay among saturation properties and astrophysical observables depends not only on the thermal configurations considered but also on the constraints imposed. We also investigated the role of nuclear saturation parameters on some universal relations for hot NSs which are important in gravitational wave asteroseismology. Our investigation confirmed that these relations are mostly insensitive to nuclear saturation properties and mainly affected by variation of charge fraction in the star.