The capture of dark matter particles through the evolution of low-mass stars

TL;DR

This study analyzes how different assumptions about dark matter properties and stellar physics affect the rate at which stars capture dark matter particles, highlighting uncertainties and dependencies crucial for using stars as dark matter detectors.

Contribution

It investigates the influence of stellar physics and dark matter characteristics on the dark matter capture rate in low-mass stars, considering different scattering cross section scenarios.

Findings

Capture rate characteristics vary significantly between scenarios.

Uncertainties in stellar mass and dark matter velocity impact capture rate estimates.

Results help assess the reliability of stars as dark matter probes.

Abstract

We studied the rate at which stars capture dark matter (DM) particles, considering different assumptions regarding the DM characteristics and in particular investigating how the stellar physics influences the capture rate. Two scenarios were considered: first, we assumed the maximal values for the spin-dependent and spin-independent DM particle-nucleon scattering cross sections allowed by the limits from direct detection experiments. Second, we considered that both scattering cross sections are of the same order, with the aim of studying the dependencies of the capture rate on stellar elements other than hydrogen. We found that the characteristics of the capture rate are very different in the two scenarios. Furthermore, we quantified the uncertainties on the computed capture rate (C_x) and on the ratio between the luminosities from DM annihilations and thermonuclear reactions (L_x/L_nuc) derived from an imprecise knowledge of the stellar structure and DM parameters. For instance, while an uncertainty of 10% on the typical DM velocity leads to similar errors on the computed C_x and L_x/L_nuc, the same uncertainty on the stellar mass becomes more relevant and duplicates the errors. Our results may be used to evaluate the reliability of the computed capture rate for the hypothetical use of stars other than the Sun as DM probes.