Astrophysical black holes are expected to be described by the Kerr metric. This is the only
stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies …

Astrophysical black holes are expected to be described by the Kerr metric. This is the only
stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies …

In this paper, we analyze the light rays around a static hairy black hole in Horndeski gravity
with the use of ray-tracing procedure. We find that a stronger Horndeski hairy parameter …

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 …

The optical appearance of a body compact enough to feature an unstable bound orbit, when
surrounded by an accretion disk, is expected to be dominated by a luminous ring of radiation …

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 silhouette of a black hole having a critical curve (an unstable bound photon orbit) when
illuminated by an optically thin accretion disk whose emission is confined to the equatorial …

Eikonal quasinormal modes (QNMs) of black holes (BHs) and parameters of null geodesics,
ultimately tied to the appearance of BHs to external observers, are known to be related, and …

In the present work, we investigate the image of a power-Yang-Mills black hole and its
luminosity under distinctive accretion models. Meanwhile, a special emphasis is put on the …