Stellar Structure of Dark Stars: a first phase of Stellar Evolution due to Dark Matter Annihilation

TL;DR

Dark Stars are early universe stars powered by dark matter annihilation, exhibiting unique properties such as high mass, large size, and specific spectral lines, differing significantly from standard metal-free stars.

Contribution

This paper models the structure and evolution of Dark Stars, providing the first equilibrium configurations and predicting observable properties for stars powered by dark matter annihilation.

Findings

Dark Stars can reach masses up to 1000 solar masses.

They have luminosities of a few million times that of the Sun.

Dark Stars are cooler, larger, and more massive than standard metal-free stars.

Abstract

Dark Stars are the very first phase of stellar evolution in the history of the universe: the first stars to form (typically at redshifts $z \sim 10-50$) are powered by heating from dark matter (DM) annihilation instead of fusion (if the DM is made of particles which are their own antiparticles). We find equilibrium polytropic configurations for these stars; we start from the time DM heating becomes important ($M \sim 1-10 M_\odot$) and build up the star via accretion up to 1000 M$_\odot$. The dark stars, with an assumed particle mass of 100 GeV, are found to have luminosities of a few times $10^6$ L$_\odot$, surface temperatures of 4000--10,000 K, radii $\sim 10^{14}$ cm, lifetimes of at least $ 0.5$ Myr, and are predicted to show lines of atomic and molecular hydrogen. Dark stars look quite different from standard metal-free stars without DM heating: they are far more massive (e.g. $\sim 800 M_\odot$ for 100 GeV WIMPs), cooler, and larger, and can be distinguished in future observations, possibly even by JWST or TMT.