Neutron Stars and Dark Matter

TL;DR

This paper investigates how dark matter accumulation affects neutron star structure, showing that increased dark matter density near galactic centers can lead to neutron star collapse into black holes, constraining dark matter interactions.

Contribution

It provides a detailed analysis of dark matter effects on neutron stars, including the impact of dark matter properties and environment, and constrains dark matter interaction cross sections.

Findings

Dark matter accumulation decreases neutron star mass near galactic centers.

Beyond a critical dark matter density, neutron stars collapse into black holes.

Constraints on dark matter-nucleon and dark matter self-interaction cross sections.

Abstract

Neutron stars change their structure with accumulation of dark matter. We study how their mass is influenced from the environment. Close to the sun, the dark matter accretion from the neutron star does not have any effect on it. Moving towards the galactic center, the density increase in dark matter results in increased accretion. At distances of some fraction of a parsec, the neutron star acquire enough dark matter to have its structure changed. We show that the neutron star mass decreases going towards the galactic centre, and that dark matter accumulation beyond a critical value collapses the neutron star into a black hole. Calculations cover cases varying the dark matter particle mass, self-interaction strength, and ratio between the pressure of dark matter and ordinary matter. This allow us to constrain the interaction cross section, $\sigma_{\rm dm}$, between nucleons and dark matter particles, as well as the dark matter self-interaction cross section.