Cosmic rays from primordial black holes and constraints on the early universe

Abstract

The constraints on the number of evaporating primordial black holes imposed by observations of the cosmological gamma-ray background do not exclude their making a significant contribution to the Galactic flux of cosmic ray photons, electrons, positrons and antiprotons. Even if this contribution is small, cosmic ray data place important limits on the number of evaporating black holes and thereby on models of the early Universe. Evaporating black holes are unlikely to be detectable in their final explosive phase unless new physics is invoked at the QCD phase transition.