Relic neutrino decay: a solution to the excess radio background

Abstract: The detection of excess radio background detected by ARCADE 2 suggests the presence of new physics as there exists no clear astrophysical solution. We find that the radiative decay of a relic neutrino into a sterile neutrino, assumed to be quasi-degenerate, provides a very good fit to ARCADE 2 data. The solution also predicts a stronger 21 cm absorption global signal than the predicted one from the $\Lambda$CDM model, with a contrast brightness temperature. The solution obtained is in mild tension with a much stronger signal claimed by the EDGES collaboration.