Neutron star cooling after deep crustal heating in the X-ray transient KS 1731-260

TL;DR

This paper models the cooling process of the neutron star in KS 1731-260 after a long outburst, highlighting the role of deep crustal heating and specific crust properties in the cooling behavior.

Contribution

It provides a detailed simulation of neutron star cooling post-outburst, emphasizing the effects of deep crustal heating and crust properties without requiring enhanced neutrino emission.

Findings

Cooling consistent with deep crustal heating during outburst

Crust is thin, superfluid, with normal thermal conductivity

Crust-core relaxation may still be ongoing

Abstract

We simulate the cooling of the neutron star in the X-ray transient KS 1731-260 after the source returned to quiescence in 2001 from a long (>~ 12.5 yr) outburst state. We show that the cooling can be explained assuming that the crust underwent deep heating during the outburst stage. In our best theoretical scenario the neutron star has no enhanced neutrino emission in the core, and its crust is thin, superfluid, and has the normal thermal conductivity. The thermal afterburst crust-core relaxation in the star may be not over.