# Unified equations of state for cold non-accreting neutron stars with Brussels-Montreal functionals. I. Role of symmetry energy

## TL;DR

This paper develops unified equations of state for cold neutron stars using nuclear energy-density functionals, highlighting how uncertainties in symmetry energy influence their structure and composition.

## Contribution

It introduces a comprehensive, thermodynamically consistent framework for modeling neutron stars with multiple functionals, emphasizing the role of symmetry energy.

## Key findings

- Symmetry energy uncertainties significantly affect neutron star composition.
- Analytic fits provided for practical astrophysical modeling.
- Different functionals yield consistent pressure-density relations.

## Abstract

The theory of the nuclear energy-density functional is used to provide a unified and thermodynamically consistent treatment of all regions of cold non-accreting neutron stars. In order to assess the impact of our lack of complete knowledge of the density dependence of the symmetry energy on the constitution and the global structure of neutron stars, we employ four different functionals. All of them were precision fitted to essentially all the nuclear-mass data with the Hartree-Fock-Bogoliubov method and two different neutron-matter equations of state based on realistic nuclear forces. For each functional, we calculate the composition, the pressure-density relation, and the chemical potentials throughout the star. We show that uncertainties in the symmetry energy can significantly affect the theoretical results for the composition and global structure of neutron stars. To facilitate astrophysical applications, we construct analytic fits to our numerical results.