Gravitational lensing and shadow of charged black holes in the low-energy limit of string theory

Abstract

In this work, we investigate the shadow cast and strong field gravitational lensing of a new class of black hole solutions in dilaton gravity where dilaton field is coupled with nonlinear Maxwell invariant [Younesizadeh et al. in Int J Mod Phys A 34(35):1950239]. The space-time is a stationary axisymmetric geometry. The key part in our investigations is finding the effect of dilaton parameter N on the size of shadows and the energy emission rate. As the N parameter increases, the size of black hole shadow increases. Also, the energy emission rate increases with increase in the dilaton parameter N. By supposing the gravitational field of the supermassive object at the heart of Milky Way galaxy described by this metric, we estimated the numerical values of the observables for gravitational lensing in the strong field limit.