Bounds on sterile neutrino lifetime and mixing angle with active neutrinos by global 21 cm signal

TL;DR

This paper uses the 21 cm absorption signal during cosmic dawn to set new bounds on the lifetime and mixing angle of sterile neutrinos, which are potential dark matter candidates, by analyzing their energy injection effects on the intergalactic medium.

Contribution

It introduces constraints on sterile neutrino properties based on the global 21 cm signal, providing novel astrophysical bounds compared to previous methods.

Findings

Sterile neutrino lifetime bounds are derived from the 21 cm absorption data.

Constraints on the mixing angle of sterile neutrinos are established.

Comparison shows these bounds are competitive with other astrophysical limits.

Abstract

Sterile neutrinos can be a possible candidate for dark matter. Sterile neutrinos are radiatively unstable and can inject photon energy into the intergalactic medium (IGM). The injection of photon energy into IGM can modify the temperature and ionization history of IGM gas during cosmic dawn. Theoretical models based on the {\Lambda}CDM framework predict an absorption profile in the 21 cm line during the cosmic dawn era. Recently, the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) collaboration confirmed such an adsorption signal. Injection of energy into IGM can modify the absorption amplitude in the 21 cm signal. Considering the 21 cm absorption signal at cosmic dawn, we constrain the lifetime of sterile neutrinos and the mixing angle of sterile neutrinos with active neutrinos. We also compare these bounds with other astrophysical observational bounds.