Primordial black holes and gravitational waves in teleparallel Gravity

TL;DR

This paper explores how teleparallel gravity influences primordial black hole formation and gravitational wave production, aligning theoretical predictions with Planck observational constraints.

Contribution

It demonstrates the impact of teleparallel parameters on inflationary dynamics, PBH abundance, and GW signals, providing new insights into early universe physics within this framework.

Findings

Teleparallel parameter δ=3 yields e-folds consistent with Planck data.

PBH overproduction can occur at specific non-adiabatic power spectrum parameters.

Preheating duration ≤ 2 aligns with observational bounds on tensor-to-scalar ratio.

Abstract

In this paper, we consider the possible effect of the teleparallel gravity on the production of the primordial black holes (PBH) and on the gravitational waves (GWs). We investigate the relationship between the slow roll, the e-folds number and the teleparallel parameters. We show that in the case of the teleparallel parameter $\delta =3$, the e-folds number reaches the values $50$ and $60$ in consistency with the contour plot of the $(r,n_{s})$ plane obtained by Planck data at $1\sigma $ and $2\sigma $ C.L.. Furthermore, we use the fraction of the energy density and the variance of the density perturbations approach to study the abundance of the production PBH. We find that the PBH overproduction can be satisfied for specific values of parameters of the non-adiabatic curvature power spectrum at some narrow parametric resonance. Moreover, to explain the GWs expected by observations, the duration of preheating should be bounded by values less or equal to $2$. This bound is in agreement with values of the tensor-to-scalar ratio and the spectral index constrained by Planck data.