Dark Matter annihilations in Pop III stars

TL;DR

This paper investigates how WIMP dark matter annihilations affect the evolution of Population III stars, potentially creating long-lived, observable 'frozen' stars with unique mass-radius relations in the early universe.

Contribution

It introduces a modified stellar evolution model to study dark matter effects on Pop III stars, revealing conditions for stars to become WIMP-powered and observable.

Findings

Stars can be sustained solely by WIMP annihilations at high dark matter densities.

WIMP-powered stars exhibit anomalous mass-radius relations distinguishable from normal stars.

Such 'frozen' stars could be detected in the local universe due to their unique properties.

Abstract

We study the impact of the capture and annihilation of Weakly Interacting Massive Particles (WIMPs) on the evolution of Pop III stars. With a suitable modification of the Geneva stellar evolution code, we study the evolution of 20 and 200 M$_\odot$ stars in Dark Matter Haloes with densities between 10$^{8}$ and $10^{11}$ GeV/cm$^3$ during the core H-burning phase, and, for selected cases, until the end of the core He-burning phase. We find that for WIMP densities higher than 5.3 $10^{10}(\sigma^{SD}_p/10^{-38} {cm}^2)^{-1}$ GeV cm$^{-3}$ the core H-burning lifetime of $20 M_{\odot}$ and $200 M_{\odot}$ stars exceeds the age of the Universe, and stars are sustained only by WIMP annihilations. We determine the observational properties of these `frozen` objects and show that they can be searched for in the local Universe thanks to their anomalous mass-radius relation, which should allow unambiguous discrimination from normal stars.