The effects of self-interacting bosonic dark matter on neutron star properties

TL;DR

This paper models self-interacting bosonic dark matter's impact on neutron star properties, revealing how different distributions of dark matter can mimic or alter the star's observable characteristics, with implications for future astrophysical observations.

Contribution

It introduces a two-fluid formalism to study bosonic dark matter effects on neutron stars, providing new constraints on dark matter parameters and potential observational signatures.

Findings

Condensed dark matter softens the star's EoS, reducing mass and radius.

Dark matter halos increase the star's tidal deformability and mass.

Constraints on dark matter properties based on neutron star observations.

Abstract

We propose a model of asymmetric bosonic dark matter (DM) with self-repulsion mediated by the vector field coupled to the complex scalar particles. By adopting the two-fluid formalism, we study different DM distribution regimes, either, fully condensed inside the core of a star or, otherwise, distributed in a dilute halo around a neutron star (NS). We show that DM condensed in a core leads to a decrease of the total gravitational mass, radius and tidal deformability compared to a pure baryonic star with the same central density, which we will perceive as an effective softening of the equation of state (EoS). On the other hand, the presence of a DM halo increases the tidal deformability and total gravitational mass. As a result, an accumulated DM inside compact stars could mimic an apparent stiffening of strongly interacting matter equation of state and constraints we impose on it at high densities. From the performed analysis of the effect of DM particles in a MeV-GeV mass-scale, interaction strength, and relative DM fractions inside NSs we obtained a rigorous constraint on model parameters. Finally, we discuss several smoking guns of the presence of DM that are free from the above mentioned apparent modification of the strongly interacting matter equation of state. With this we could be probed with the future astrophysical and gravitational wave (GW) surveys.