Primordial black holes generated by the non-minimal spectator field

TL;DR

This paper introduces a model where a non-minimally coupled spectator field during inflation enhances small-scale perturbations, leading to primordial black holes that could account for dark matter and produce detectable gravitational waves.

Contribution

The study presents a novel mechanism involving non-minimal coupling to generate primordial black holes and predicts observable gravitational wave signals.

Findings

Primordial black holes can constitute all dark matter with masses around 10^{-12} solar masses.

Enhanced small-scale perturbations produce detectable gravitational waves.

Future space-based detectors can observe these gravitational waves.

Abstract

In this paper, we propose a model in which a spectator field non-minimally couples to an inflaton field and the power spectrum of the perturbation of the spectator field at small scales is dramatically enhanced by the sharp feature in the form of non-minimal coupling. At or after the end of inflation, the perturbation of the spectator field is converted into curvature perturbation and leads to the formation of primordial black holes (PBHs). Furthermore, for example, we consider three phenomenological models for generating PBHs with mass function peaked at $\sim10^{-12}M_\odot$ and representing all the cold dark matter in our Universe and find that the scalar induced gravitational waves generated by the curvature perturbation can be detected by the future space-borne gravitational-wave detectors such as Taiji, TianQin and LISA.