Lensing by gravitational waves in scalar-tensor gravity: Einstein frame analysis

TL;DR

This paper investigates how gravitational waves in scalar-tensor gravity affect light lensing, showing that amplification effects differ between Einstein and Jordan frames, with implications for VLBI observations.

Contribution

It clarifies the lensing effects of gravitational waves in scalar-tensor gravity within the Einstein frame, contrasting previous Jordan frame results.

Findings

Amplification of light by gravitational waves is not as large in the Einstein frame.

Lensing effects are relevant for VLBI detection of gravitational wave scintillation.

Differences between frames impact gravitational wave observational signatures.

Abstract

The amplification of a light beam due to intervening gravitational waves is studied. The previous Jordan frame result according to which the amplification is many orders of magnitude larger in scalar-tensor gravity than in general relativity does not hold in the Einstein conformal frame. Lensing by gravitational waves is discussed in relation to the ongoing and proposed VLBI observations aimed at detecting the scintillation effect.