Light deflection and shadow of charged black hole in a Born-Infeld-type electrodynamics

Original Abstract

We investigate the spacetime geometry of a black hole solution coupled to a nonlinear Born-Infeld-type electrodynamics of the Kruglov form, taking into account the effective geometry governing photon propagation. Our analysis focuses on the role of parameter $q$, which controls deviations from Maxwell electrodynamics. We study observational signatures including light deflection, the black holes shadow, and images of a thin accretion disk. We find that the effective photon geometry induces significant modifications to null trajectories, leading to systematic $q$-dependent shifts in the deflection angle, shadow radius, and lensing observables. In particular, smaller positive values of $q$ enhance light bending, while negative values produce the opposite trend. Moreover, the efective geometry admits stable photon orbits outside the event horizon in certain regions of parameter space, together with nonstandard (reversal direction of) angular behavior of photon trajectories. These features leave distinct imprints on accretion disk images, especially in the structure and visibility of photon rings.