Bispectrum of induced gravitational waves in the poltergeist mechanism

TL;DR

This paper calculates the bispectrum of induced gravitational waves in the poltergeist mechanism, revealing distinctive peaks that can differentiate it from other GW sources, based on a sudden transition approximation.

Contribution

It provides the first detailed calculation of the tensor bispectrum in the poltergeist mechanism, highlighting its unique scale-dependent features.

Findings

Bispectrum peaks in equilateral or squeezed configurations.

Characteristic behavior distinguishes it from other GW mechanisms.

Analysis uses sudden transition approximation.

Abstract

In the poltergeist mechanism the enhancement of induced gravitational waves (GWs) occurs due to a sudden transition from an early matter-dominated era to the radiation-dominated era. In this work, we calculate the bispectrum of induced GWs from the poltergeist mechanism by adopting the sudden transition approximation. We find that the tensor bispectrum peaks either in the equilateral or squeezed configurations, depending on scales. Such a characteristic behavior enables us to distinguish it from that from other GW generation mechanisms.