Primordial black hole dark matter from inflation: the reverse engineering approach

TL;DR

This paper introduces a reverse engineering method linking late-time cosmological observables to inflationary dynamics, revealing conditions for primordial black hole formation and associated signals.

Contribution

It presents a novel approach to connect inflationary models with observable signatures, enabling targeted exploration of primordial black hole and gravitational wave phenomena.

Findings

Inflation can produce a raised plateau in the curvature perturbation spectrum.

This spectrum feature can lead to primordial black holes as dark matter.

Detectable gravitational wave signals may accompany black hole formation.

Abstract

Constraining the inflationary epoch is one of the aims of modern cosmology. In order to fully exploit current and future small-scale observations, it is necessary to devise tools to directly relate them to the early universes dynamics. We present here a novel reverse engineer approach able to connect fundamental late-time observables to consistent inflationary dynamics and, eventually, to the inflaton potential. Employing this procedure, we are able to describe which conditions can give rise to a raised plateau in the power spectrum of curvature perturbations at small scales, which are not constrained by CMB observations. Within this new phenomenologically-driven approach, we find that inflation can generate a raised plateau in the spectrum of curvature perturbations that potentially connects three fundamental observables: a dominant component of the dark matter in the form of asteroid-mass/atomic-size primordial black holes; detectable signals in stochastic gravitational waves and a subdominant fraction of stellar-mass primordial black holes mergers.