Decaying dark matter: a stacking analysis of galaxy clusters to improve   on current limits
  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. 
C. Combet, D. Maurin, E. Nezri, E. Pointecouteau, J. A. Hinton, R.   White
astro-ph.CO astro-ph.HE hep-ph