Strong field gravitational lensing in stringy black hole

Abstract

In this paper, we studied the strong gravitational lensing due to the stringy black hole using the strong field limit approach. Modeling the supermassive object at the galactic center as stringy black hole, the numerical values of the strong field limit coefficients and the observables were estimated. Moreover, by measuring the observables, one can get the strong field limit coefficients to reconstruct the full expansion of the deflection angle for the strong field gravitational lensing in stringy black hole. Comparing our results with that of Schwarzschild black hole, it is easy to find that all the values in stringy black hole diverge from those of Schwarzschild spacetime under the influence of the parameter α, which gives us an alternative way to distinguish the stringy black hole from the Schwarzschild black hole. In our model, with the parameter α increasing, the angular position θ ∞ increases and the relative magnitudes $\mathcal{R}_{m}$ decreases.