Cooling of Neutron Stars admixed with Light Dark Matter: a case study

TL;DR

This study explores how the presence of light dark matter within neutron stars could alter their cooling behavior, potentially explaining discrepancies in observed cooling data and offering new insights into dark matter's role in stellar evolution.

Contribution

It introduces a novel model of neutron star cooling that includes admixed light dark matter with self-annihilation and thermal conduction effects, providing a new perspective on observed cooling anomalies.

Findings

Dark matter presence can significantly modify neutron star cooling curves.

Self-annihilating dark matter affects neutrino emission and thermal evolution.

Cooling patterns may serve as indirect evidence for light dark matter in neutron stars.

Abstract

Neutron Stars (NSs) are born as hot, lepton-rich objects that evolve according to the standard paradigm through subsequent stages where they radiate the excess of energy by emitting, first, neutrinos and, later on, photons. Current descriptions based on Standard Model calculations cannot fully explain all the existing cooling data series for the dozens of objects that have been reported. In this work, we consider the intriguing possibility that cooling NSs could be actually admixed with a fraction of light dark matter (LDM), $\chi$. We focus on a particular case study assuming a generic light candidate with mass $m_\chi=0.1$ $\rm GeV/c^2$ that undergoes self-annihilating reactions through pseudoscalar mediators producing neutrinos in the final state. We include one additional feature, allowing thermal conduction from LDM while inside the dark core. By performing simulations of the temperature evolution in the NS, we find that cooling patterns could be distorted by the presence of LDM and discuss these results in light of their observability.