Decaying dark matter in halos of primordial black holes

Abstract

Abstract We investigate photon signatures of general decaying dark-matter particles in halos of primordial black holes. We derive the halo-profile density and the total decay rate for these combined dark-matter scenarios. For the case of axion-like particles of masses below $$\mathcal {O}( 1 )\mathrm{keV}$$ O(1)keV , we find strong bounds on the decay constant which are several orders of magnitude stronger than the strongest existing bounds, for all halo masses above $$\mathcal {O}( 10^{-5} )$$ O(10-5) solar masses. Using future X-ray measurements, it will be possible to push these bounds on such combined dark-matter scenarios even further.