Strong gravitational lensing by braneworld black holes

In this paper, we use the strong field limit approach to investigate the gravitational lensing properties of braneworld black holes. Applying this method to the supermassive black hole at the center of our galaxy, the lensing observables for some candidate braneworld black hole metrics are compared with those for the standard Schwarzschild case. It is found that braneworld black holes could have significantly different observational signatures to the Schwarzschild black hole.

Figure 1

Gravitational lensing diagram.

Figure 2

General behavior of the deflection angle as a function of $r_0$. As $r_0$ decreases, $\alpha$ increases, and each time it reaches a multiple of $2\pi$ the photon completes a loop around the black hole.

Figure 3

SFL coefficients for the $U=0$ metric (31), as functions of $r_h$. The standard Schwarzschild case is given by $r_h=1/4$.

Figure 4

SFL coefficients for the tidal Reissner-Nordström metric (33), as functions of $q$. The standard Schwarzschild case given by $q=0$.