Primordial black holes from a curvaton scenario with strongly non-Gaussian perturbations

TL;DR

This paper explores how a strongly non-Gaussian curvaton scenario during inflation can produce primordial black holes, especially in the asteroid mass range, without affecting large-scale CMB perturbations.

Contribution

It demonstrates that a quadratic curvaton with strong non-Gaussianity can generate PBHs on small scales while remaining negligible on CMB scales, with specific mass and abundance predictions.

Findings

PBHs in the asteroid mass range can form with high abundance.

The curvaton contribution to CMB scales remains negligible.

PBH formation is feasible with inflationary Hubble scale above 10^{12} GeV.

Abstract

We investigate the production of primordial black holes (PBHs) in a mixed inflaton-curvaton scenario with a quadratic curvaton potential, assuming the curvaton is in de Sitter equilibrium during inflation with $\langle \chi\rangle =0$. In this setup, the curvature perturbation sourced by the curvaton is strongly non-Gaussian, containing no leading Gaussian term. We show that for $m^2/H^2\gtrsim 0.3$, the curvaton contribution to the spectrum of primordial perturbations on CMB scales can be kept negligible but on small scales the curvaton can source PBHs. In particular, PBHs in the asteroid mass range $10^{-16}M_{\odot}\lesssim M\lesssim 10^{-10}M_{\odot}$ with an abundance reaching $f_{\rm PBH} = 1$ can be produced when the inflationary Hubble scale $H\gtrsim 10^{12}$ GeV and the curvaton decay occurs in the window from slightly before the electroweak transition to around the QCD transition.