Gravitational Lensing and Gravitomagnetic Time Delay

TL;DR

This paper derives the effect of a rotating body's spin on photon travel time delays and explores its potential detectability in gravitational lensing, which could impact measurements of the Hubble constant and dark matter estimates.

Contribution

It introduces a new theoretical framework for spin-induced time delays in gravitational lensing and discusses their observational implications.

Findings

Spin of astrophysical objects causes measurable time delays in gravitational lensing.

Potential to improve Hubble constant measurements through spin-time delay detection.

Provides a method to estimate dark matter content via spin-time delay observations.

Abstract

We derive the delay in travel time of photons due to the spin of a body both inside a rotating shell and outside a rotating body. We then show that this time delay by the spin of an astrophysical object might be detected in different images of the same source by gravitational lensing; it might be relevant in the determination of the Hubble constant using accurate measurements of the time delay between the images of some gravitational lens systems. The measurement of the spin-time-delay might also provide a further observable to estimate the dark matter content in galaxies, clusters, or super-clusters of galaxies.