Primordial black holes formation in the inflationary model with field-dependent kinetic term for quartic and natural potentials

TL;DR

This paper explores how a field-dependent kinetic term in inflationary models with quartic and natural potentials can produce primordial black holes and gravitational waves consistent with observations, potentially explaining dark matter.

Contribution

It introduces a kinetic function that allows standard inflationary potentials to align with Planck data and enhances small-scale perturbations for PBH formation.

Findings

PBHs with mass $10^{-13}M_{ m ext{sun}}$ can account for all dark matter.

Enhanced scalar power spectrum at specific small scales leads to PBH production.

Induced gravitational wave energy density follows a power-law spectrum in the infrared limit.

Abstract

Within the framework of inflationary model with field-dependent kinetic term for quartic and natural potentials, we investigate generation of the primordial black holes (PBHs) and induced gravitational waves (GWs). In this setup, we consider a kinetic function as $G(\phi)=g_I(\phi)\big(1+g_{II}(\phi)\big)$ and show that in the presence of first term $g_I(\phi)$ both quartic and natural potentials, in contrast to the standard model of inflation, can be consistent, with the 68\% CL of Planck observations. Besides, the second term $g_{II}(\phi)$ can cause a significant enhancement in the primordial curvature perturbations at the small scales which results the PBHs formation. For the both potentials, we obtain an enhancement in the scalar power spectrum at the scales $k\sim10^{12}~\rm Mpc^{-1}$, $10^{8}~\rm Mpc^{-1}$, and $10^{5}~\rm Mpc^{-1}$, which causes PBHs production in mass scales around $10^{-13}M_{\odot}$, $10^{-5}M_{\odot}$, and $10 M_{\odot}$, respectively. Observational constraints confirm that PBHs with a mass scale of $10^{-13}M_{\odot}$ can constitute the total of dark matter in the universe. Furthermore, we estimate the energy density parameter of induced GWs which can be examined by the observation. Also we conclude that it can be parametrized as a power-law function $\Omega_{\rm GW}\sim (f/f_c)^n$, where the power index equals $n=3-2/\ln(f_c/f)$ in the infrared limit $f\ll f_{c}$.