Impact of Dark Matter Annihilation on the High-Redshift Intergalactic Medium

Understand

We reexamine the impact of dark matter (DM) annihilation on the intergalactic medium, taking into account the clumping of DM particles.

• We find that energy injection from the annihilation of the thermal relic DM particles may significantly raise the gas temperature at high redshifts and leave a strong imprint on the cosmological 21-cm signal, provided the particle mass is below ~1 TeV.
• Further, we find that while the energy injection from DM annihilation could not alone complete the reionization of the Universe, it could make a significant contribution to the electron optical depth.