We study an impact of asymmetric fermionic dark matter on neutron star properties, including tidal deformability, mass, radius, etc. We present the conditions at which dark matter particles tend to form a compact structure in a core of the star or create an extended halo around it. We show that compact core of dark matter leads to a decrease of the total gravitational mass and tidal deformability compared to a pure baryonic star, while presence of a dark matter halo increases those observable quantities. By imposing an existing astrophysical and gravitational wave constraints set by LIGO/Virgo Collaboration together with the recent results on the spatial distribution of dark matter in the Milky Way we determine a new upper limit on the mass and fraction of dark matter particles inside compact stars. Furthermore, we show that the formation of an extended halo around a NS is incompatible with the GW170817 tidal deformability constraint.
@article{arxiv.2111.13289,
title = {Constraints on the fermionic dark matter from observations of neutron stars},
author = {V. Sagun and E. Giangrandi and O. Ivanytskyi and I. Lopes and K. A. Bugaev},
journal= {arXiv preprint arXiv:2111.13289},
year = {2021}
}