Experimental constraints on shallow heating in accreting neutron-star crusts

TL;DR

This paper estimates the maximum heat deposition in neutron-star crusts from nuclear reactions triggered by accretion, providing constraints on shallow heating sources based on experimental nuclear data.

Contribution

It introduces a method to quantify the upper limits of shallow heating in neutron-star crusts using experimental nuclear reaction data.

Findings

Maximum heat deposition estimates for neutron-star crusts.

Constraints on shallow heating sources in accreting neutron stars.

Implications for thermal relaxation models of neutron stars.

Abstract

The observed thermal relaxation of transiently accreting neutron stars during quiescence periods in low-mass X-ray binaries suggests the existence of unknown heat sources in the shallow layers of neutron-star crust. Making use of existing experimental nuclear data, we estimate the maximum possible amount of heat that can be deposited in the outer crust of an accreting neutron star due to electron captures and pycnonuclear fusion reactions triggered by the burial of X-ray burst ashes.