Primordial black holes in the curvaton model: possible connections to pulsar timing arrays and dark matter

TL;DR

This paper revises primordial black hole production in the axion-curvaton model, highlighting the impact of non-gaussianities on their abundance and gravitational wave signals, and suggests this model could explain dark matter and pulsar timing array signals.

Contribution

It provides a new computation of curvature perturbation power spectrum and explores the connection between PBHs, dark matter, and pulsar timing array signals within the curvaton framework.

Findings

Non-gaussianities significantly affect PBH abundance predictions.

The model can account for dark matter in the asteroid mass range.

It potentially explains the NANOGrav and IPTA gravitational wave signals.

Abstract

We revise primordial black holes (PBHs) production in the axion-curvaton model, in light of recent developments in the computation of their abundance accounting for non-gaussianities (NGs) in the curvature perturbation up to all orders. We find that NGs intrinsically generated in such scenarios have a relevant impact on the phenomenology associated to PBHs and, in particular, on the relation between the abundance and the signal of second-order gravitational waves. We show that this model could explain both the totality of dark matter in the asteroid mass range and the tentative signal reported by the NANOGrav and IPTA collaborations in the nano-Hz frequency range. En route, we provide a new, explicit computation of the power spectrum of curvature perturbations going beyond the sudden-decay approximation.