Gravitational Waves from Preheating with Modified Gravitational-wave Propagation

TL;DR

This paper studies how the velocity of gravitational waves during preheating influences the spectrum of GWs, revealing enhancements or distortions depending on whether the velocity is less than or greater than the speed of light.

Contribution

It introduces the effect of modified GW propagation speed on the GW spectrum during preheating, providing new insights into gravitational wave production in alternative gravity models.

Findings

GW spectrum is enhanced for $c_T<1$

GW spectrum is distorted for $c_T>1$

Simulation based on $ ext{lambda}\phi^4$ inflation

Abstract

We investigate how the production of gravitational waves (GWs) is affected by the GW velocity $(c_T)$ during preheating after inflation. For instance, we simulate the production of GWs after $\lambda\phi^4$ chaotic inflation, and find that GW spectrum is enhanced for $c_T<1$, but distorted (suppressed at low frequency, but enhanced at high frequency) for $c_T>1$.