The essential singularity in Einstein's gravity can be avoidable if the preconditions of
Penrose's theorem can be bypassed, ie, if the strong energy condition is broken in the …

In this study, we review some current studies on gravitational lensing for black holes, mainly
in the context of general relativity. We mainly focus on the analytical studies related to …

Horizon-scale images of black holes (BHs) and their shadows have opened an
unprecedented window onto tests of gravity and fundamental physics in the strong-field …

We study the light rings and shadows of an uniparametric family of spherically symmetric
geometries interpolating between the Schwarzschild solution, a regular black hole, and a …

Simpson-Visser (SV) spacetimes are the simplest globally regular modifications of the
Schwarzschild, Reissner-Nordsröm and other black hole solutions of general relativity. They …

We investigate gravitational lensing by a primary photon sphere which is a sphere filled with
unstable circular light orbits, and by a secondary photon sphere on a wormhole throat in a …

We investigate the weak and strong deflection gravitational lensing by a black-bounce-
Reissner–Nordström spacetime and obtain their lensing observables. Assuming the …

Simpson and Visser recently proposed a phenomenological way to avoid some kinds of
space-time singularities by replacing a parameter whose zero value corresponds to a …

We investigate the equatorial deflection angle of light rays propagating in Kerr-Newman
black-bounce spacetime. Furthermore, we analyze the light ray trajectories and derive a …

We investigate retrolensing by two photon spheres in a novel black-bounce spacetime
suggested by Lobo et al. which can correspond to a Schwarzschild black hole, a regular …