Constraining heavy decaying dark matter with the high energy gamma-ray limits

Abstract

We consider decaying dark matter with masses $1{0}^{7}\ensuremath{\lesssim}M\ensuremath{\lesssim}1{0}^{16}\text{ }\text{ }\mathrm{GeV}$ as a source of ultrahigh energy (UHE) gamma rays. Using recent limits on UHE gamma-ray flux for energies ${E}_{\ensuremath{\gamma}}>2\ifmmode\times\else\texttimes\fi{}1{0}^{14}\text{ }\text{ }\mathrm{eV}$, provided by extensive air shower observatories, we put limits on masses and lifetimes of the dark matter. We also discuss possible dark matter decay origin of tentative 100 PeV photon flux detected with the EAS-MSU experiment.