Primordial black holes and secondary gravitational waves from inflationary model with a non-canonical kinetic term

TL;DR

This paper proposes a noncanonical inflationary model that significantly enhances small-scale primordial curvature perturbations, leading to primordial black hole formation and secondary gravitational waves, which can be tested by current observations.

Contribution

It introduces a flexible enhancement mechanism using a noncanonical kinetic term, demonstrating its ability to produce primordial black holes and gravitational waves consistent with observations.

Findings

Primordial black holes around 10^{-14}-10^{-12} solar masses can account for dark matter.

Enhanced power spectrum can have sharp or broad peaks, affecting gravitational wave signals.

Secondary gravitational waves are detectable by pulsar timing arrays and space-based observatories.

Abstract

With the enhancement mechanism provided by a noncanonical kinetic term with a peak, the amplitude of primordial curvature perturbations can be enhanced by seven orders of magnitude at small scales while keeping to be consistent with observations at large scales. The peak function and inflationary potential are not restricted in this mechanism. We use the Higgs model and T-model as examples to show how abundant primordial black hole dark matter with different mass and scalar induced secondary gravitational waves with different peak frequency are generated. We also show that the enhanced power spectrum for the primordial curvature perturbations and the energy density of the scalar induced secondary gravitational waves can have either a sharp peak or a broad peak. The primordial black holes with the mass around $10^{-14}-10^{-12} M_{\odot}$ produced with the enhancement mechanism can make up almost all dark matter, and the scalar induced secondary gravitational waves accompanied with the production of primordial black holes can be tested by the pulsar timing arrays and spaced based gravitational wave observatory. Therefore, the mechanism can be tested by primordial black hole dark matter and gravitational wave observations.