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(k>k∗), the effects of the primordial tensor perturbation with tensor-to-scalar ratio r=Ah/Aζ=0.2 lead to an around 50% increase of the signal-to-noise ratio (SNR) for LISA observations.
@article{arxiv.2209.07693,
title = {Gravitational waves from primordial scalar and tensor perturbations},
author = {Zhe Chang and Xukun Zhang and Jing-Zhi Zhou},
journal= {arXiv preprint arXiv:2209.07693},
year = {2023}
}