Distinguishing a Slowly Accelerating Black Hole by Differential Time Delays of Images

TL;DR

This paper proposes a method to detect slow acceleration in supermassive black holes through differences in gravitational lensing time delays, despite their minimal impact on black hole shadows and image positions.

Contribution

It introduces a novel observational approach to identify slowly accelerating black holes via differential time delays in gravitational lensing.

Findings

Differential time delays are significantly affected by black hole acceleration.

Black hole shadows and image positions remain largely unchanged with slow acceleration.

The proposed method could enable detection of black hole acceleration in astrophysical observations.

Abstract

Accelerating supermassive black holes, connected to cosmic strings, could contribute to structure formation and get captured by galaxies if their velocities are small. This would mean that the acceleration of these black holes is small too. Such a slow acceleration has no significant effect on the shadow of such supermassive black holes. We also show that, for slowly accelerating black holes, the angular position of images in the gravitational lensing effects do not change significantly. We propose a method to observe the acceleration of these black holes through the gravitational lensing. The method is based on the observation that differential time delays associated with the images are substantially different with respect to the case of non-accelerating black holes.