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 …

Recently, the image of a Schwarzschild black hole with an accretion disk has been revisited,
and it showed that the “photon ring,” defined as highly bent light rays that intersect the disk …

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 …

A Simpson-Visser spacetime has two non-negative parameters a and m and its metric is
correspond with (i) a Schwarzschild metric for a= 0 and m≠ 0,(ii) a regular black hole metric …

In this paper, we study light rays in a Kazakov–Solodukhin black hole. To this end, we use
the optical geometry of the Kazakov–Solodukhin black hole within the Gauss–Bonnet …

Inthispaper, wefirstusetheopticalmetricsofblack-bouncetraversablewormholestocalculatethe…
curvature. Then we use the Gauss-Bonnet theorem to obtain the weak deflection angle of …

In this paper, we use a new asymptotically flat and spherically symmetric solution in the
generalized Einstein–Cartan–Kibble–Sciama (ECKS) theory of gravity to study the weak …

In this paper, we derive an exact black hole spacetime metric in the Einstein–Hilbert–
Bumblebee (EHB) gravity around global monopole field. We study the horizon, temperature …

We investigate gravitational lensing by a photon sphere in a Reissner-Nordström naked
singularity spacetime in strong deflection limits. Because of the nonexistence of an event …

The 0th order of affine perturbation series of the deflection angle of a ray near a photon
sphere is more accurate than a deflection angle in a strong deflection limit, which is used …