Related papers: Testing General Relativity with the Shadow Size of…
Higher dimensional theories admit astrophysical objects like supermassive black holes, which are rather different from standard ones, and their gravitational lensing features deviate from general relativity. It is well known that a black…
There are now multiple direct probes of the region near black hole horizons, including direct imaging with the Event Horizon Telescope (EHT). As a result, it is now of considerable interest to identify what aspects of the underlying…
We discuss the horizon properties, shadow cast, and the weak gravitational lensing of charged rotating regular black holes, which in addition to mass ($M$) and rotation parameter ($a$) have an electric charge ($Q$) and magnetic charge…
The inferred black hole in the Galactic center spans the largest angle on the sky among all known black holes. Forthcoming observational programs plan to localize or potentially resolve the image of Sgr A* to an exquisite precision,…
In the framework of Randall -- Sundrum theory with extra dimension Reissner -- Nordstr\"om black hole solutions with a tidal charge have been found. The shadow around the supermassive black hole in M87 was reconstructed in 2019 based on…
We investigate the shadow of Kerr-Bertotti-Robinson black holes (KBRBHs), which have a deviation parameter $B$ that captures the effect of an external magnetic field on the spacetime geometry. These spacetimes of Petrov type $D$ are…
We study the shadow of a charged rotating black hole in $f(R)$ gravity. This black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and $R_{0}$ which is proportional to cosmological constant. We analyze the image of the…
Here we provide shadow images of a Kerr-like black hole (BH) in cold dark matter (CDM) halo illuminated with a celestial light source and a thin accretion disk. The impact of spin parameter, critical density and the scale radius on the…
The optical properties of rotating black holes in Kaluza-Klein theory described by the total mass, spin, and electric and magnetic charges are investigated in detail. Using a developed general relativistic ray-tracing code to calculate the…
The ring-like images of the two supermassive black holes captured by the Event Horizon Telescope (EHT) provide powerful probes of the physics of accretion flows at horizon scales. Specifically, the brightness asymmetry in the images carries…
The black hole in the center of the Milky Way, Sgr A*, has the largest mass-to-distance ratio among all known black holes in the Universe. This property makes Sgr A* the optimal target for testing the gravitational no-hair theorem. In the…
Recent observations of Sgr A* give strong constraints for possible models of the physical nature of Sgr A* and suggest the presence of a massive black~hole with M<2 10^6 M_sun surrounded by an accretion disk which we estimate to radiate at…
A black hole casts a shadow as an optical appearance because of its strong gravitational field. We study the shadow cast by the five-dimensional Myers-Perry black hole with equal rotation parameters. We demonstrate that the null geodesic…
We investigate the astrophysical consequences of black holes in quadratic gravity, characterized by the parameters $S_0$, $S_2$, $m_0$ and $m_2$, in addition to the black hole mass $M$. To evaluate the physical validity of the fundamental…
We have studied the shadows of a circular disformal Kerr black hole with a deformation parameter, which represents a rotating solution within a generalized scalar-tensor framework of Horndeski gravity that characterized by second-order…
Black hole (BH) shadow observations and gravitational wave astronomy have become crucial approaches for exploring BH physics and testing gravitational theories in extreme environments. This paper investigates the charged black hole with…
Can the observation of the "shadow" allow us to distinguish a black hole from a more exotic compact object? We study the motion of photons in a class of vacuum static axially-symmetric space-times that is continuously linked to the…
We investigate the effect of the cosmological constant on the angular size of a black hole shadow. It is known that the accelerated expansion which is created by the cosmological constant changes the angular size of the black hole shadow…
We study nonsingular black holes viewed from the point of view of Ayon-Beato-Garcia (ABG) nonlinear electrodynamics (NLED) and present a complete study of their corresponding strong gravitational lensing. The NLED modifies the the photon's…
In a previous paper, one of us has showed that, at least in some cases, the Kerr-nature of astrophysical black hole candidates is extremely difficult to test and current techniques, even in presence of excellent data not available today,…