Lensing Signatures of a Slowly-Accelerated Black Hole

TL;DR

This paper investigates how slow acceleration of black holes affects gravitational lensing, showing that while image positions remain nearly unchanged, time delays between images are significantly affected, providing a potential test for deviations from general relativity.

Contribution

It demonstrates that slow acceleration in black holes influences gravitational lensing time delays without altering image positions, offering a new observational signature to test gravity theories.

Findings

Time delays are significantly affected by black hole acceleration.

Image positions remain consistent with general relativity predictions.

Deviations in observed time delays could indicate black hole acceleration or new physics.

Abstract

Accelerating black holes, connected to cosmic strings could evolve to supermassive black holes. However, if they are going to take part in structure formation and resides at the center of galaxies, their acceleration should be small. This slow acceleration does not change the shadow or image position in gravitational lensing effect significantly. However we show that the time delay associated to these images change significantly. This is in contrast with when the theory governing the strong gravitational field around the black hole is different from general relativity, where not only the differential time delays but the angular position of images would be different. We conclude that, if the observed angular position of images are compatible with the prediction of general relativity, a possible deviation in the differential time delays between the observed values and those predicted by general relativity, could be due to the acceleration of the black hole.