Expanding Microscopic Black Holes

TL;DR

This paper investigates the behavior of expanding microscopic black holes, exploring their potential role in dark matter and universe expansion, and finds observational evidence against their cosmological coupling.

Contribution

It combines hypotheses about microscopic black holes being dark matter candidates and coupled to cosmic expansion, analyzing their radiation balance and observational constraints.

Findings

Two temperature points for radiation-expansion balance identified

One balance point could influence primordial universe models

Observed gamma-ray background contradicts the cosmological coupling hypothesis

Abstract

Two interesting hypotheses about black holes have been proposed. The older one states that microscopic black holes can be accountable for the observed dark matter density. The newer one states that black holes are coupled to the expansion of the universe. Here, we combine those ideas and investigate the behaviour of expanding microscopic black holes. We observe two temperatures at which the radiation balances the expansion. While one of the balance points might be important in the analysis of primordial scenarios, the other would lead to a strong diffuse gamma radiation background, which is contradicted by the lack of observations. This establishes another indirect evidence disfavouring the hypothesis of cosmological coupling of black holes.