Inflation driven by repulsive-like primordial black holes

TL;DR

This paper discusses a novel inflationary mechanism driven by repulsive-like primordial black holes within a cosmological model, leading to early universe expansion, reheating, and potential solutions to the Hubble tension.

Contribution

It introduces a new inflationary scenario involving PBHs with specific masses and abundances, highlighting their role in early universe dynamics and dark energy.

Findings

Light PBHs (< 5×10^8 g) induce exponential inflation with graceful exit.

PBHs around 10^{12} g can act as early dark energy, easing the Hubble tension.

Universe with PBHs exhibits a quasi-de-Sitter expansion phase.

Abstract

We review a new natural inflationary mechanism operated by repulsive-like primordial black holes (PBHs). In particular, working within the ``Swiss - Cheese" cosmological framework, we find that a Universe filled with PBHs, whose spacetime metric presents a repulsive-like behaviour, is characterised by an early quasi-de-Sitter cosmic expansion phase. Notably, for light PBHs with $m < 5 \times 10^8 \mathrm{g}$, evaporating before Big Bang Nucleosynthesis (BBN), one is met with an exponential inflationary phase with graceful exit and reheating proceeding through PBH evaporation. Furthermore, one finds as well that PBHs with $m \sim 10^{12}\mathrm{g}$ and abundances $0.107 < \Omega^\mathrm{eq}_\mathrm{PBH} < 0.5$ near matter-radiation equality can act as an early dark energy component, easing in this way naturally the Hubble tension.