Towards Testing Sterile Neutrino Dark Matter with Spectrum-Roentgen-Gamma Mission

TL;DR

This paper explores how the SRG space mission's X-ray surveys can detect or constrain keV-scale sterile neutrino dark matter, potentially surpassing previous limits and providing independent verification of signals like the 3.5 keV line.

Contribution

It demonstrates that the SRG mission's ART-XC and eROSITA telescopes can significantly improve constraints on sterile neutrino dark matter parameters across a broad energy range.

Findings

eROSITA's sensitivity near 3.5 keV will be comparable to XMM-Newton after four years.

Constraints below 2.4 keV will be stronger than previous XMM-Newton results.

ART-XC data could yield more stringent constraints than NuSTAR in the 5-20 keV range.

Abstract

We investigate the prospects of the SRG mission in searches for the keV-scale mass sterile neutrino dark matter radiatively decaying into active neutrino and photon. The ongoing all-sky X-ray survey of the SRG space observatory with data acquired by the ART-XC and eROSITA telescopes can provide a possibility to fully explore the resonant production mechanism of the dark matter sterile neutrino, which exploits the lepton asymmetry in the primordial plasma consistent with cosmological limits from the Big Bang Nucleosynthesis. In particular, it is shown that at the end of the four year all-sky survey, the sensitivity of the eROSITA telescope near the 3.5 keV line signal reported earlier can be comparable to that of the XMM-Newton with all collected data, which will allow one to carry out another independent study of the possible sterile neutrino decay signal in this area. In the energy range below $\approx2.4$ keV, the expected constraints on the model parameters can be significantly stronger than those obtained with XMM-Newton. From the ART-XC data, in the energy range approximately from 5 to 20 keV, it can be possible to get more stringent constraints than those obtained with NuSTAR so far. We conclude that the SRG mission has a very high potential in testing the sterile neutrino dark matter hypothesis.