Relic neutrino decay: a solution to the excess radio background

TL;DR

This paper proposes that the radiative decay of relic neutrinos into sterile neutrinos can explain the excess radio background observed by ARCADE 2, offering a potential new physics solution with implications for 21 cm signals.

Contribution

It introduces a novel neutrino decay model that fits the ARCADE 2 radio excess and predicts a stronger 21 cm absorption signal, linking particle physics with cosmological observations.

Findings

Neutrino decay model fits ARCADE 2 data well

Predicts a stronger 21 cm absorption signal than standard models

Mild tension with EDGES 21 cm measurement

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.