Primordial black hole formation from the merger of oscillons

TL;DR

This paper demonstrates that oscillon mergers produce a broad mass spectrum, leading to a significant formation of primordial black holes without the need for tuning inflationary models.

Contribution

It introduces a novel mechanism for primordial black hole formation via oscillon mergers, bypassing traditional fine-tuning of inflationary potentials.

Findings

Oscillon mergers result in a heavy-mass exponential tail in the mass distribution.

A sizable abundance of primordial black holes can be produced from oscillons.

The mechanism does not require tuning of the inflaton potential.

Abstract

We show that the merger of oscillons results in a broad spectrum of the oscillon mass. A huge number of oscillon samples obtained from numerical lattice simulations reveal that the oscillon mass distribution has an exponential tail in a heavy-mass region. This enables us to infer the fractional abundance of heavy oscillons. Using the criterion for the primordial black hole (PBH) formation from the oscillon collapse obtained in previous studies, we estimate the abundance of PBHs and conclude that a sizable number of PBHs can be produced from oscillons. It can be an alternative PBH formation mechanism without employing the tuning of the inflaton potential to enhance the small-scale density fluctuations in the conventional PBH formation scenario.