Speaker
Description
Numerous quanta of soft dark radiation ( e.g. more abundant than CMB photons) could be created in the early Universe by means of various non-thermal processes. The dark radiation
can be resonantly converted to the "normal" photons, creating over-population of Rayleigh-Jeans photons, increasing the contrast of the 21 cm absorption feature. We construct specific classes of models to that effect, where the dark radiation in the form of the dark photons is sourced by the decay of sub-eV dark matter particles. We show that such models are perfectly consistent with all astrophysical, cosmological and terrestrial data, and 21 cm physics provides the leading constraint on it. In a more speculative vein, the strength of the EDGES signal can also be explained suing such a setup.
