Decaying dark matter: a stacking analysis of galaxy clusters to improve on current limits

TL;DR

This paper demonstrates that stacking galaxy clusters significantly enhances the sensitivity of all-sky gamma-ray instruments like Fermi-LAT in constraining decaying dark matter, using the largest X-ray-selected cluster sample.

Contribution

It introduces a stacking analysis method for galaxy clusters that improves dark matter decay limits by a factor of 5-100 over single-source analyses.

Findings

Stacking improves dark matter decay limits by up to 100 times.

Utilizes the largest X-ray-selected galaxy cluster catalog (MCXC).

Provides astrophysical parameters necessary for current gamma-ray analyses.

Abstract

We show that a stacking approach to galaxy clusters can improve current limits on decaying dark matter by a factor $\gtrsim 5-100$, with respect to a single source analysis, for all-sky instruments such as Fermi-LAT. Based on the largest sample of X-ray-selected galaxy clusters available to date (the MCXC meta-catalogue), we provide all the astrophysical information, in particular the astrophysical term for decaying dark matter, required to perform an analysis with current instruments.