Revisiting Primordial Black Hole Evolution

• Main Authors: Maxim Khlopov, Biplab Paik, Saibal Ray
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: Axioms
• Subjects: cosmology; particle physics; primordial black hole; baryon accretion; forbidden regime; high energy physics
• Online Access: https://www.mdpi.com/2075-1680/9/2/71

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 <i>growth versus evaporation rate</i> 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 <inline-formula> <math display="inline"> <semantics> <mrow> <mi>M</mi> <mo>≤</mo> <mn>5</mn> <mo>.</mo> <mn>5</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>13</mn> </msup> </mrow> </semantics> </math> </inline-formula> g. On the other hand, we propose the mechanism of delay of evaporation of primordial population of PBHs of primordial mass range <inline-formula> <math display="inline"> <semantics> <mrow> <mn>5</mn> <mo>.</mo> <mn>5</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>13</mn> </msup> <mspace width="3.33333pt"></mspace> <mi mathvariant="normal">g</mi> <mo>≤</mo> <mi>M</mi> <mo>≤</mo> <mn>5</mn> <mo>.</mo> <mn>1</mn> <mo>×</mo> <msup> <mn>10</mn> <mn>14</mn> </msup> </mrow> </semantics> </math> </inline-formula> g. It can provide their evaporation to be the main contributor to <inline-formula> <math display="inline"> <semantics> <mi>γ</mi> </semantics> </math> </inline-formula>-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.