Tensor induced gravitational waves

TL;DR

This paper studies second-order tensor induced gravitational waves generated by primordial gravitational waves, showing that large small-scale primordial waves can significantly affect the gravitational wave energy spectrum, especially in certain frequency bands.

Contribution

It introduces the analysis of second-order tensor induced gravitational waves sourced by primordial waves and highlights their impact on the energy density spectrum at small scales.

Findings

Corrections from second-order TIGWs can be significant when primordial waves dominate PTA observations.

Large amplitude primordial gravitational waves at small scales influence the total gravitational wave spectrum.

Potential detectability of these effects in specific frequency bands.

Abstract

Primordial gravitational waves on small scales are not tightly constrained by current cosmological observations, which allows for the possibility of large amplitudes at small scales. We investigate second-order tensor induced gravitational waves (TIGWs) sourced by primordial gravitational waves and present the corresponding corrections to the total energy density spectrum of gravitational wave. We analyze primordial gravitational waves with large amplitudes generated by various models at small scales. Our results indicate that when primordial gravitational waves on small scales sufficiently dominate the current PTA observations, corrections to the total energy density spectrum from second-order TIGWs may become pronounced in certain frequency bands.