# Dark Matter Annihilation in the Circumgalactic Medium at High Redshifts

## TL;DR

This study develops a detailed energy deposition model to evaluate how annihilating dark matter influences baryonic structures and the circumgalactic medium at high redshifts, revealing significant effects on star formation thresholds.

## Contribution

It introduces a comprehensive energy deposition code for high-redshift dark matter annihilation and compares different halo models and annihilation channels.

## Key findings

- Dark matter annihilation increases minimal star-forming halo mass by up to 5 times.
- Energy deposition varies with halo profile and redshift, affecting baryonic structure.
- Annihilation spectra influence the heating of the circumgalactic medium.

## Abstract

Annihilating dark matter (DM) models offer promising avenues for future DM detection, in particular via modification of astrophysical signals. However when modelling such potential signals at high redshift the emergence of both dark matter and baryonic structure, as well as the complexities of the energy transfer process, need to be taken into account. In the following paper we present a detailed energy deposition code and use this to examine the energy transfer efficiency of annihilating dark matter at high redshift, including the effects on baryonic structure. We employ the PYTHIA code to model neutralino-like DM candidates and their subsequent annihilation products for a range of masses and annihilation channels. We also compare different density profiles and mass-concentration relations for 10^5-10^7 M_sun haloes at redshifts 20 and 40. For these DM halo and particle models, we show radially dependent ionisation and heating curves and compare the deposited energy to the haloes' gravitational binding energy. We use the "filtered" annihilation spectra escaping the halo to calculate the heating of the circumgalactic medium and show that the mass of the minimal star forming object is increased by a factor of 2-3 at redshift 20 and 4-5 at redshift 40 for some DM models.