Thermal states of neutron stars with a consistent model of interior

TL;DR

This paper models the thermal states of neutron stars using a consistent interior model, highlighting the necessity of the direct Urca process and specific superfluid properties to match observations of various neutron star populations.

Contribution

It introduces a comprehensive model with consistent equations of state and superfluid gaps, providing new insights into neutron star cooling mechanisms and observational consistency.

Findings

Direct Urca process is essential for low-luminosity accreting neutron stars.

Proton superfluidity and weak neutron superfluidity are key for explaining middle-aged neutron star cooling.

Model matches observed thermal states across different neutron star types.

Abstract

We model the thermal states of both isolated neutron stars and accreting neutron stars in X-ray transients in quiescence and confront them with observations. We use an equation of state and superfluid baryon gaps, which are consistently calculated. We conclude that the direct Urca process is required to be consistent with low-luminous accreting neutron stars. In addition, proton superfluidity and sufficiently weak neutron superfluidity are necessary to explain the cooling of middle-aged neutron stars and to obtain a realistic distribution of neutron star masses.