Enhanced Neutrino Cooling from Parity-Doubled Nucleons in Neutron Star Cooling Simulations

TL;DR

This paper models neutron star cores with a parity doublet approach, revealing that parity partner Urca processes significantly influence neutron star cooling and improve alignment with observations.

Contribution

It introduces a parity doublet model into neutron star cooling simulations, accounting for chiral symmetry restoration and parity partner effects on thermal evolution.

Findings

Parity partner Urca processes significantly affect neutron star cooling.

Inclusion of these processes improves agreement with observed surface temperatures.

Model predicts appearance of parity partners at high densities.

Abstract

Although restoration of chiral symmetry is predicted by quantum chromodynamics to take place at high baryon density, most modeling of neutron star interiors disregards a chiral phase transition. We model neutron star cores with a parity doublet model, which allows for dynamical chiral symmetry restoration and predicts the appearance of the parity partners of nucleons and hyperons at large densities, as well as deconfined quark matter. We study the thermal evolution of neutron stars, focusing for the first time on the impact of Urca processes involving the parity partners in neutron star cooling simulations. We find that Urca processes for the parity partners of the nucleons significantly affect the thermal evolution of massive stars and allow for improved agreement with observed surface temperature and ages.