Dark Matter Annihilation in the First Galaxy Halos

TL;DR

This paper explores how energy from dark matter annihilation in early small halos could heat gas enough to prevent star formation, potentially delaying galaxy formation.

Contribution

It models the impact of dark matter annihilation on gas heating in high-redshift halos using particle physics simulations and analytic methods.

Findings

Dark matter annihilation energy exceeds gas binding energy in early halos.

Energy injection can prevent star formation in primordial halos.

Dark matter annihilation may delay the formation of the first galaxies.

Abstract

We investigate the impact of energy released from self-annihilating dark matter on heating of gas in the small, high-redshift dark matter halos thought to host the first stars. A SUSY neutralino like particle is implemented as our dark matter candidate. The PYTHIA code is used to model the final, stable particle distributions produced during the annihilation process. We use an analytic treatment in conjunction with the code MEDEA2 to find the energy transfer and subsequent partition into heating, ionizing and Lyman alpha photon components. We consider a number of halo density models, dark matter particle masses and annihilation channels. We find that the injected energy from dark matter exceeds the binding energy of the gas within a $10^5$ - $10^6$ M$_\odot$ halo at redshifts above 20, preventing star formation in early halos in which primordial gas would otherwise cool. Thus we find that DM annihilation could delay the formation of the first galaxies.