PREPRINT
F19955D4-82AB-47B7-96C6-733B76647B82

# Gravitational waves from primordial scalar and tensor perturbations

Zhe Chang, Xukun Zhang, Jing-Zhi Zhou

Submitted on 15 September 2022

## Abstract

We investigate the second order gravitational waves induced by the primordial scalar and tensor perturbations during radiation-dominated era. The explicit expressions of the power spectra of the second order GWs are presented. We calculate the energy density spectra of the second order GWs for a monochromatic primordial power spectra. For large $k$ $\left(k>{k}_{\ast }\right)$, the effects of the primordial tensor perturbation with tensor-to-scalar ratio $r={A}_{h}/{A}_{\zeta }=0.2$ lead to an around $50\mathrm{%}$ increase of the signal-to-noise ratio (SNR) for LISA observations.

## Preprint

Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics; General Relativity and Quantum Cosmology