Non-linear interaction between the electromagnetic fields (EMF) occurs when vacuum
polarization in quantum electrodynamics (QED) happens. The field of non-linear …

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 …

Thanks to the release of the extraordinary EHT image of shadow attributed to the M87*
supermassive black hole (SMBH), we have a novel window to assess the validity of …

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 …

In this present work, we study the observational appearance of Kerr-Melvin black hole
(KMBH) illuminated by an accretion disk. The accretion disk is assumed to be located on the …

A bstract For a static and spherically symmetric black hole, a photon sphere is composed of
circular null geodesics of fixed radius, and plays an important role in observing the black …

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 …