Constraining Mirror Dark Matter Inside Neutron Stars

TL;DR

This paper explores how mirror dark matter inside neutron stars affects their maximum mass and deformability, providing constraints on dark matter content based on observational data and highlighting the impact on universal relations.

Contribution

It introduces a model incorporating mirror dark matter into neutron star structure, analyzing its effects on maximum mass, tidal deformability, and universal relations.

Findings

Mirror dark matter lowers maximum neutron star mass.

Mirror dark matter decreases tidal deformability.

Universal relations are modified by mirror dark matter.

Abstract

We inspect the possibility that neutron star interiors are a mixture of ordinary matter and mirror dark matter. This is a scenario that can be naturally envisaged according to well studied accretion mechanisms, including the Bondi-Hoyle one. We show that the inclusion of mirror dark matter in neutron star models lowers the maximum neutron star mass for a given equation of state, and that it decreases the tidal deformability of a given neutron star. These general features imply that, given an equation of state, one can constrain the maximum viable amount of mirror dark matter in neutron stars in order to consistently fulfill existing maximum mass and tidal deformability constraints. Conversely, using tidal deformability measurements to rule out equations of state requires making assumptions on the amount of mirror dark matter contained in neutron stars. Finally, the presence of mirror dark matter also modifies the universal relation that links the tidal deformability of a neutron star to its compactness. Therefore, caution is mandatory when considering exotic models, such as the ones discussed in this paper.