The impact of EDGES 21-cm data on dark matter interactions

Abstract

The recently announced results on the 21-cm absorption spectrum by the EDGES experiment can place very stringent limits on dark matter annihilation cross-sections. We properly take into account the heating energy released from dark matter annihilation from the radiation epoch to the 21-cm observation redshifts in the radiative transfer to compute the evolution of the gas temperature. Our results show that the global 21-cm absorption profile is a powerful cosmological probe of the dark matter interactions. For dark matter annihilating into electron-positron pairs, the EDGES results give a more stringent upper limit than the PLANCK result on the annihilation cross section at the lower dark matter mass region.