Effects of scalar non-Gaussianity on induced scalar-tensor gravitational waves

TL;DR

This paper investigates how scalar non-Gaussianity influences scalar-tensor induced gravitational waves, extending previous models to include non-Gaussian effects and analyzing their impact on the gravitational wave spectrum.

Contribution

It introduces a local expansion for scalar non-Gaussianity in the scalar-tensor sector equations, extending prior work on scalar-scalar interactions.

Findings

New term in gravitational wave spectrum from scalar non-Gaussianity

Distinctive features identified in the spectrum due to non-Gaussian effects

Enhanced understanding of gravitational wave signals from inflationary models

Abstract

If primordial scalar or tensor perturbations are enhanced on short scales, it may lead to the production of observable gravitational wave signals. These waves may be sourced by scalar-scalar, scalar-tensor or tensor-tensor interactions. Typically, models of inflation capable of producing large peaks in the scalar primordial power spectrum also generate sizeable scalar non-Gaussianity. Previous studies have investigated the possible effects of this on the scalar-scalar induced gravitational wave spectrum by assuming a local expansion in terms of the parameters $F_{\textrm{NL}}$, $G_{\textrm{NL}}$ and so on. We extend this approach to the case of scalar-tensor induced gravitational waves, introducing a local expansion for scalar non-Gaussianity into the scalar-tensor sector equations. We compute the contribution to the gravitational wave spectrum from the resulting new term and analyse its distinguishing features.