Microlensing events and primordial black holes in the axionlike curvaton model

TL;DR

This paper explores how axionlike curvaton models can produce primordial black holes that explain recent microlensing events observed by Subaru HSC, with implications for dark matter and gravitational waves.

Contribution

It demonstrates that axionlike curvaton models can account for observed microlensing events via primordial black holes and discusses related cosmological consequences.

Findings

Primordial black holes with masses of 10^{-7} to 10^{-6} solar masses can explain the microlensing events.

Axionlike curvaton models predict enhanced small-scale curvature perturbations leading to PBH formation.

The model's implications include potential gravitational wave signals.

Abstract

Recently, Subaru Hyper Suprime-Cam (HSC) observations found 12 candidates for microlensing events. These events can be explained by primordial black holes (PBHs) with masses of $10^{-7}$-$10^{-6} M_\odot$ and a fraction of all dark matter of $f_\mathrm{PBH} = \mathcal{O}(10^{-1})$. In this paper, we consider the PBH production in two types of the axionlike curvaton models, which predict an enhancement of the curvature perturbations on small scales. We show that the microlensing events can be explained in the axionlike curvaton model and discuss the cosmological implications such as gravitational waves.