Hawking heating of neutron stars by dark matter

Abstract

Interactions with particle dark matter could brighten old, isolated neutron stars to thermal luminosities detectable at current and next-generation telescopes. We present a novel mechanism for such signals. Non-annihilating (e.g., asymmetric) dark matter capturing in a neutron star could form a small black hole in its core, which could then rapidly evaporate away. If black holes form and evaporate within the cooling timescale of the neutron star, periodic episodes of black hole evaporation could impart a steady-state stellar luminosity, providing a source of heat additional to the kinetic energy of dark matter during capture. Consequently, we obtain sensitivities to dark matter-nucleon cross sections that are stronger than that from dark kinetic heating by a factor of a few for > $10^4$ GeV (> $10^{10}$ GeV) mass of spin-0 (spin-1/2) dark matter.