Neutron stars: new constraints on asymmetric dark matter

TL;DR

This paper investigates how asymmetric dark matter influences neutron star properties, especially their maximum mass, providing new constraints on dark matter particle mass and distribution within stars based on astrophysical observations.

Contribution

It introduces a novel analysis linking dark matter properties with neutron star mass limits, offering updated constraints on dark matter particle mass and fraction inside stars.

Findings

Dark matter can reduce neutron star maximum mass, but light particles can increase visible mass.

Detection of 2 solar mass neutron stars near the Galactic center constrains dark matter particle mass to ~60 GeV.

Future observations will tighten constraints on dark matter properties within neutron stars.

Abstract

We study an impact of asymmetric dark matter on properties of the neutron stars and their ability to reach the two solar masses limit, which allows us to present a new range of masses of dark matter particles and their fractions inside the star. Our analysis is based on the observational fact of the existence of two pulsars reaching this limit and on the theoretically predicted reduction of the neutron star maximal mass caused by the accumulation of dark matter in its interior. We also demonstrate that light dark matter particles with masses below 0.2 GeV can create an extended halo around the neutron star leading not to decrease, but to increase of its visible gravitational mass. By using recent results on the spatial distribution of dark matter in the Milky Way, we present an estimate of its fraction inside the neutron stars located in the Galaxy center. We show how the detection of a 2 Msun neutron star in the most central region of the Galaxy will impose an upper constraint on the mass of dark matter particles of ~ 60 GeV. Future high precision measurements of the neutron stars maximal mass near the Galactic center, will put a more stringent constraint on the mass of the dark matter particle. This last result is particularly important to prepare ongoing, and future radio and x-ray surveys.