Title: Dark Matter in Light of the 21cm EDGES Signal
Speaker: Ely Kovetz, Johns Hopkins
Abstract: Cosmology with the 21cm signal, in particular from the epoch surrounding the birth of the first stars, known as cosmic dawn, holds tremendous promise for the search for dark matter.
Recently, the EDGES collaboration claimed a detection of an absorption profile of CMB photons in neutral hydrogen at frequencies corresponding to cosmic dawn redshifts.
The measured amplitude of the absorption trough is several standard deviations stronger than allowed by the concordance cosmological model, indicating that either the background radiation temperature was much higher than expected, or that the gas temperature at the cosmic dawn epoch was much lower than expected. The latter had been predicted as a possible signature of coulomb-type interactions between dark matter and baryons. I will describe the EDGES measurement and its suggested explanation via millicharged dark matter, placing emphasis on the strong constraints to this model.
Lastly, I will independently show how a detection of 21cm absorption at cosmic dawn can be used to place the strongest constraints to date on models of ultra-light hidden photon dark matter across more than ten orders of magnitude in mass.