Primordial black holes from fifth forces

TL;DR

This paper explores a novel mechanism where a fifth force mediated by a light scalar field causes density fluctuations to collapse into primordial black holes, potentially accounting for all dark matter.

Contribution

It introduces a new formation scenario for primordial black holes driven by a fifth force, independent of inflationary density fluctuation features.

Findings

Primordial black holes can form via a fifth force without inflationary spectrum features.

Such black holes could potentially make up all dark matter.

The mechanism involves rapid nonlinear growth of overdensities when heavy particle energy fraction crosses a threshold.

Abstract

Primordial black holes can be produced by a long range attractive fifth force stronger than gravity, mediated by a light scalar field interacting with nonrelativistic "heavy" particles. As soon as the energy fraction of heavy particles reaches a threshold, the fluctuations rapidly become nonlinear. The overdensities collapse into black holes or similar screened objects, without the need for any particular feature in the spectrum of primordial density fluctuations generated during inflation. We discuss whether such primordial black holes can constitute the total dark matter component in the Universe.