Revisiting CMB constraints on dark matter annihilation

Understand

The precision measurements of the cosmic microwave background power spectrum put a strong constraint on the dark matter annihilation cross section since the electromagnetic energy injection by the dark matter annihilation affects the ionization history of the universe.

• In this paper, we update our previous simulation code for calculating the ionization history with the effect of dark matter annihilation by including Helium interactions and improving the precision of calculations.
• We give an updated constraint on the annihilation cross section and mass of dark matter using the modified RECFAST code with the Planck 2018 datasets.