Primordial black holes and induced gravitational waves from logarithmic non-Gaussianity

TL;DR

This paper explores how logarithmic non-Gaussianities influence primordial black hole formation and the resulting gravitational wave signals, with implications for dark matter and recent pulsar timing array observations.

Contribution

It provides numerical analysis of PBH formation thresholds and predicts detectable gravitational wave signals from logarithmic non-Gaussianities in upcoming experiments.

Findings

Certain parameter spaces yield maximum critical thresholds for PBH formation.

No PBH production occurs from type II fluctuations in some regions, contrary to previous studies.

SIGW signals from logarithmic non-Gaussianities could be detected if PBHs make up all dark matter.

Abstract

We investigate the formation of primordial black hole (PBH) based on numerical relativity simulations and peak theory as well as the corresponding scalar induced gravitational wave (SIGW) signals in the presence of \emph{logarithmic non-Gaussianities} which has recently been confirmed in a wide class of inflation models. Through numerical calculations, we find certain parameter spaces of the critical thresholds for the type A PBH formation and reveal a maximum critical threshold value. We also find that there is a region where no PBH is produced from type II fluctuations contrary to a previous study. We then confirm that SIGW signals originated from the logarithmic non-Gaussianity are detectable in the Laser Interferometer Space Antenna if PBHs account for whole dark matter. Finally, we discuss the SIGW interpretation of the nHz stochastic gravitational wave background reported by the recent pulsar timing array observations. We find that PBH overproduction is a serious problem for most of the parameter space, while this tension might still be alleviated in the non-perturbative regime.