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

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.