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