Primordial black hole dark matter in dilaton-extended two-field Starobinsky inflation

TL;DR

This paper explores how a dilaton two-field extension of Starobinsky inflation can produce primordial black holes that account for dark matter, using a multi-field amplification mechanism that creates a peak in the power spectrum.

Contribution

It introduces a novel multi-field inflation model that generates primordial black holes as dark matter candidates, differing from traditional single-field models.

Findings

The model produces a sharp peak in the power spectrum at small wavelengths.

Primordial black holes formed in the model can explain the observed dark matter.

The inflationary phase aligns with cosmic microwave background observations.

Abstract

We investigate the production of primordial black holes and their contribution to the presently observed dark matter in a dilaton two-field extension of Starobinsky's quadratic $f(R)$ model of inflation. The model features a multi-field amplification mechanism which leads to the generation of a sharp peak in the inflationary power spectrum at small wavelengths responsible for the production of primordial black holes. This mechanism is significantly different from single-field models and requires a stochastic treatment during an intermediate phase of the inflationary dynamics. We find that the model leads to a successful phase of effective single-field Starobinsky inflation for wavelengths probed by the cosmic microwave background radiation and explains the observed cold dark matter content in the Universe by the formation of primordial black holes.