Primordial Black Hole Formation in Non-Minimal Curvaton Scenario

Abstract

In the curvaton scenario, the curvature perturbation is generated after inflation at the curvaton decay, which may have a prominent non-Gaussian effect. For a model with a non-trivial kinetic term, an enhanced curvature perturbation on a small scale can be realized, which can lead to copious production of primordial black holes (PBHs) and induce secondary gravitational waves (GWs). We find that under the assumption that thus formed PBHs would not overclose the universe, the non-Gaussianity of the curvature perturbation can be well approximated by the local quadratic form. When the curvaton energy fraction is small at the moment of curvaton decay, both the PBH abundance and the induced GW spectrum depends only on the power spectrum of the curvature perturbation. If asteroid-mass PBHs are the cold dark matter of the universe, we have \(\Omega_\text{IGW}\gtrsim10^{-11}\) at \(\sim10^{-2}~\text{Hz}\), which is detectable in the planned space GW detectors such as LISA.