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 …

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 …

In this paper, we first consider null geodesics of a class of charged, spherical and
asymptotically flat hairy black holes in an Einstein-Maxwell-scalar theory with a nonminimal …

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 …

The geodesics of the Ellis-Bronnikov wormhole with two parameters are studied. The
asymmetric wormhole has only one light ring and one innermost stable circular orbit located …

In the Randall-Sundrum braneworld scenario, there has been no exact rotating black hole
solutions throughout the whole spacetime so far. Instead, a Kerr-Newman-like metric …

Photon spheres play a pivotal role in the imaging of luminous objects near black holes. In
this paper, we examine observational appearances of a star freely falling in hairy black …

We consider reflection-asymmetric thin-shell wormholes within Palatini f (R) gravity using a
matching procedure of two patches of electrovacuum space-times at a hypersurface (the …

Recently, a distinct shadow mechanism was proposed by Wang et al. from the asymmetric
thin-shell wormhole (ATW)[X. Wang, Phys. Lett. B 811, 135930 (2020) PYLBAJ 0370-2693 …