Abstract
Primordial black holes (PBHs) are the sensitive probe for physics and cosmology of very early Universe. The observable effect of their existence depends on the PBH mass. Mini PBHs evaporate and do not survive to the present time, leaving only background effect of products of their evaporation, while PBHs evaporating now can be new exotic sources of energetic particles and gamma rays in the modern Universe. Here we revisit the history of evolution of mini PBHs. We follow the aspects associated with growth versus evaporation rate of “a mini PBH being trapped inside intense local cosmological matter inhomogeneity”. We show that the existence of baryon accretion forbidden black hole regime enables constraints on mini PBHs with the mass M ≤ 5.5 × 10 13 g. On the other hand, we propose the mechanism of delay of evaporation of primordial population of PBHs of primordial mass range 5.5 × 10 13 g ≤ M ≤ 5.1 × 10 14 g. It can provide their evaporation to be the main contributor to γ -ray flux distribution in the current Universe. At the final stage of evaporation these PBHs can be the source of ultrahigh energy cosmic rays and gamma radiation challenging probe for their existence in the LHAASO experiment.
Highlights
Ever since it was proposed, Hawking’s idea of glowing black hole [1] remained a standout theoretical effort towards merging quantum mechanics with the general theory of gravity.The prediction was that a black hole of mass M should act like a black-body of temperature6.2 × 10−8 × ( M/MJ )−1 Kelvins, having radiation consisting of photons, neutrinos, and even all sorts of massive particles as M gets small enough [1,2]
Further we shall provide a rigorous basis for why a baryon accretion forbidden regime should be feasible in any physical circumstance
Since a lower bound to the energy scale of untested physics lies in the TeV range [6] whereas a regime of mini black hole that forbids ordinary matter accretion begins to work at a classical GeV energy scale, the works in [4,5] appear barely physical even in exotic physics arena
Summary
Ever since it was proposed, Hawking’s idea of glowing black hole [1] remained a standout theoretical effort towards merging quantum mechanics with the general theory of gravity. Since a PBH in reality would always interact with its surroundings, in presence of intense environmental matter in-homogeneities a significant prolongation could be expected over the period of complete decay of a PBH that gets trapped inside some gas-matter lump in early Universe In this context a baryon accretion forbidden regime could lead to a constrained picture of PBH-evaporation events and consequences, basically since the ‘decay time prolongation’ is possible only for a black hole that does not hold the accretion forbidden regime.
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