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.
