Strong field gravitational lensing by a charged Galileon black hole

TL;DR

This paper investigates the strong field gravitational lensing effects caused by a charged Galileon black hole, calculating observable quantities that could help distinguish it from other black hole types in astrophysical observations.

Contribution

It provides the first detailed analysis of relativistic images and lensing observables for a charged Galileon black hole, highlighting potential methods to differentiate it from other black holes.

Findings

Relativistic image positions and time delays are calculated for the charged Galileon black hole.

Lensing observables can be similar to those of Reissner-Nordström black holes, complicating differentiation.

Separation of outermost relativistic images could help distinguish black hole types, given advanced observational techniques.

Abstract

Strong field gravitational lensings are dramatically disparate from those in the weak field by representing relativistic images due to light winds one to infinity loops around a lens before escaping. We study such a lensing caused by a charged Galileon black hole, which is expected to have possibility to evade no-hair theorem. We calculate the angular separations and time delays between different relativistic images of the charged Galileon black hole. All these observables can potentially be used to discriminate a charged Galileon black hole from others. We estimate the magnitudes of these observables for the closest supermassive black hole Sgr A*. The strong field lensing observables of the charged Galileon black hole can be close to those of a tidal Reissner-Nordstr\"{o}m black hole or those of a Reissner-Nordstr\"{o}m black hole. It will be helpful to distinguish these black holes if we can separate the outermost relativistic images and determine their angular separation, brightness difference and time delay, although it requires techniques beyond the current limit.