Searching for dark matter X-ray lines from the Large Magellanic Cloud with eROSITA

TL;DR

This study searches for dark matter decay signals in X-ray data from the Large Magellanic Cloud using eROSITA, setting new constraints on sterile neutrino and axion-like particle properties.

Contribution

First analysis of eROSITA X-ray data targeting dark matter decay lines in the Large Magellanic Cloud, providing new limits on DM particle parameters.

Findings

No evidence of dark matter decay lines detected.

Established new lower limits on DM lifetime.

Set tighter constraints on sterile neutrino and ALP parameters below 5 keV.

Abstract

We perform a search for an X-ray monochromatic line arising from dark matter (DM) decay in the halo of the Large Magellanic Cloud. An emission line can be expected from two well-motivated DM candidates: sterile neturinos and axion-like particles (ALPs). We analyze the eROSITA-DE DR1 datasets in the energy range between 1 and 9 keV. No evidence for a DM line is found, and we set lower limits on the DM lifetime. We then recast these bounds into upper limits on the active-sterile neutrino mixing angle $\sin^2(2\theta)$ and on the ALP to photon coupling $g_{a\gamma}$, for DM masses between 2 and 18 keV. These results set new strong constraints for masses below 5 keV.