In this article, we provide a review of the current state of the research of the black hole
shadow, focusing on analytical (as opposed to numerical and observational) studies. We …

The theory of gravitational lensing is reviewed from a spacetime perspective, without quasi-
Newtonian approximations. More precisely, the review covers all aspects of gravitational …

We study the shadows cast by the different types of rotating regular black holes viz. Ayón-
Beato-García (ABG), Hayward, and Bardeen. These black holes have in addition to the total …

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 …

The shadow of a rotating non-Kerr black hole has been studied, and it was shown that in
addition to the specific angular momentum a, the deformation parameter of non-Kerr …

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 …

We investigate the shadow cast by a rotating braneworld black hole, in the Randall-
Sundrum scenario. In addition to the angular momentum, the tidal charge term deforms the …

The Chern-Simons modification to general relativity in four dimensions consists of adding to
the Einstein-Hilbert term a scalar field that couples to the first-class Pontryagin density. In …

We review the theoretical aspects of gravitational lensing by black holes, and discuss the
perspectives for realistic observations. We will first treat lensing by spherically symmetric …