Propagating Gravitational Waves in Teleparallel Gauss-Bonnet Gravity

TL;DR

This paper investigates gravitational wave propagation in teleparallel Gauss-Bonnet gravity, showing that gravitational waves travel at light speed and deriving related propagation equations and distance-duality relations.

Contribution

It extends the analysis of gravitational waves to teleparallel Gauss-Bonnet theories, demonstrating their compatibility with observed wave speeds and deriving new propagation equations.

Findings

Gravitational waves propagate at the speed of light in these theories.

Derived the gravitational wave propagation equation in teleparallel Gauss-Bonnet gravity.

Established the distance-duality relationship for radiation in this framework.

Abstract

Gravitational waves offer a key insight into the viability of classes of gravitational theories beyond general relativity. The observational constraints on their speed of propagation can provide strong constraints on generalized classes of broader gravitational frameworks. In this work, we reconsider the general class of Gauss-Bonnet theories in the context of teleparallel gravity, where the background geometry is expressed through torsion. We perform tensor perturbations on a flat FLRW background, and derive the gravitational wave propagation equation. We find that gravitational waves propagate at the speed of light in these classes of theories. We also derive the distance-duality relationship for radiation propagating in the gravitational wave and electromagnetic domains.