Strong gravitational field time delay for photons coupled to Weyl tensor in a Schwarzschild black hole

TL;DR

This paper investigates how photons coupled to the Weyl tensor experience time delays in a Schwarzschild black hole's strong gravitational field, revealing polarization-dependent effects and potential observational methods.

Contribution

It introduces an analysis of polarization effects on photon time delays in strong gravity, using the strong deflection limit in Schwarzschild spacetime.

Findings

Time delays are significantly affected by polarization directions.

Resolving relativistic images enhances polarization detection.

Measurement of time delays can improve polarization determination.

Abstract

We analyse strong gravitational field time delay for photons coupled to the Weyl tensor in a Schwarzschild black hole. By making use of the method of strong deflection limit, we find that these time delays between relativistic images are significantly affected by polarization directions of such a coupling. A practical problem about determination of the polarization direction by observations is investigated. It is found that if the first and second relativistic images can be resolved, the measurement of time delay can more effectively improve detectability of the polarization direction.