Bondi accretion of dark matter by neutron stars

TL;DR

This study compares Bondi accretion and previous models for dark matter accumulation in neutron stars, showing how dark matter heating influences surface temperature and highlighting the importance of accretion mechanism choice at higher dark matter densities.

Contribution

It demonstrates the significance of Bondi accretion over Kouvaris's model for dark matter capture in neutron stars at higher densities, affecting surface temperature predictions.

Findings

Bondi accretion dominates at dark matter densities above 3.81 GeV/cm^3.

Dark matter heating can raise neutron star surface temperature to about 1.12×10^5 K.

Surface temperature plateau appears around 10^{6.5} years.

Abstract

In this paper, we have compared two different accretion mechanisms of dark matter particles by a canonical neutron star with $M=1.4~M_{\odot}$ and $R=10~{\rm km}$, and shown the effects of dark matter heating on the surface temperature of star. We should take into account the Bondi accretion of dark matter by neutron stars rather than the accretion mechanism of Kouvaris (2008) \citep{Kouvaris08}, once the dark matter density is higher than $\sim3.81~\rm GeV/cm^3$. Based on the Bondi accretion mechanism and heating of dark matter annihilation, the surface temperature platform of star can appear at $\sim 10^{6.5}$ year and arrive $\sim 1.12\times10^5$ K for the dark matter density of $3.81~\rm GeV/cm^3$, which is one order of magnitude higher than the case of Kouvaris (2008) with dark matter density of $30~\rm GeV/cm^3$.