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 …

In this paper, using the recent method proposed by Ono, Ishihara and Asada (OIA) who
extend the idea of Gibbons and Werner to the stationary and axisymmetric case, we apply …

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 …

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 …

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 …

In the strong deflection gravitational lensing, given the fact that a black-bounce, traversable
wormhole is indistinguishable from a Schwarzschild black hole and is loosely tested by the …

This paper is devoted to computing the weak deflection angle for the Kalb–Ramond
traversable wormhole solution in plasma and dark matter mediums by using the method of …

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 …

We investigate precessing and periodic geodesic motions of timelike particles around a
black-bounce/traversable wormhole. After obtaining its semi-classic and relativistic …

Here we shall show how to reconstruct the shape function of a spherically symmetric
traversable Lorenzian wormhole near its throat if one knows high frequency quasinormal …