Bosonic Dark Matter in Neutron Stars and its Effect on Gravitational Wave Signal

TL;DR

This paper investigates how self-interacting bosonic dark matter influences neutron star properties and gravitational wave signals, providing constraints on dark matter fraction and particle mass based on astrophysical observations.

Contribution

It offers a detailed analysis of dark matter effects on neutron star structure and gravitational wave signals, especially for sub-GeV bosonic dark matter with self-interactions.

Findings

Constraints on dark matter fraction below 5% for sub-GeV bosons.

Dark matter distribution depends on mass and fraction, forming cores or halos.

Observations of massive neutron stars and tidal deformability limit dark matter properties.

Abstract

We study an impact of self-interacting bosonic dark matter (DM) on various observable properties of neutron stars (NSs). The analysis is performed for asymmetric DM with masses from few MeV to GeV, the self-coupling constant of order $\mathcal{O}(1)$ and various DM fractions. Allowing a mixture between DM and baryonic matter, the formation of a dense DM core or an extended dark halo have been explored. We find that both distribution regimes crucially depend on the mass and fraction of DM for sub-GeV boson masses in the strong coupling regime. From the combined analysis of the mass-radius relation and the tidal deformability of compact stars including bosonic DM, we set a stringent constraint on DM fraction. We conclude that observations of 2$M_{\odot}$ NSs together with $\Lambda_{1.4}\leq580$ constraint, set by LIGO/Virgo Collaboration, favour sub-GeV DM particles with low fractions below $\sim 5 \%$.