Detection of gravitational waves by light perturbation

TL;DR

This paper demonstrates how gravitational waves perturb light signals by solving Maxwell's equations in curved spacetime, showing how these perturbations can be used to detect gravitational waves through pulsar timing arrays.

Contribution

It provides a general analytical framework for understanding light perturbations caused by gravitational waves from arbitrary directions, linking Maxwell's equations with null geodesic analysis.

Findings

Perturbation of light leads to measurable delays in photon transit time.

The analysis applies to arbitrary directions of light and gravitational wave propagation.

Response of pulsar timing arrays varies with incident angle of light pulses.

Abstract

Light undergoes perturbation as gravitational waves pass by. This is shown by solving Maxwell's equations in a spacetime with gravitational waves; a solution exhibits a perturbation due to gravitational waves. We determine the perturbation for a general case of both light and gravitational waves propagating in arbitrary directions. It is also shown that a perturbation of light due to gravitational waves leads to a delay of the photon transit time, which implies an equivalence between the perturbation analysis of Maxwell's equations and the null geodesic analysis for photon propagation. We present an example of application of this principle with regard to the detection of gravitational waves via a pulsar timing array, wherein our perturbation analysis for the general case is employed to show how the detector response varies with the incident angle of a light pulse with respect to the detector.