Related papers: Lensing By Sgr A* as a Probe of Modified Gravity
Millimeter very long baseline interferometry will soon produce accurate images of the closest surroundings of the supermassive compact object at the center of the Galaxy, Sgr A*. These images may reveal the existence of a central faint…
The metric for a Reissner-Nordstr$\ddot{o}$m black hole in the background of the Friedman-Robertson-Walker universe is obtained. Then we verified it and discussed the influence of the evolution of the universe on the size of the black hole.…
We study axial perturbations of Reissner-Nordstr\"{o}m black holes within the general framework of parity-violating modified gravity theories. We derive the governing equations for a class of frame-dragging perturbations, focusing on the…
The Event Horizon Telescope (EHT) has recently observed the image and shadow of the supermassive compact object Sagittarius A$^*$ (Sgr A$^*$). According to the EHT collaboration, the observed image is consistent with the expected appearance…
This paper explores the possibility of determining the spin of the supermassive black hole (SMBH) in Sgr A*, by using secondary images of stars orbiting the SMBH. The photons propagate close to the SMBH and their trajectories probe the…
Context. The supermassive black hole, Sagittarius (Sgr) A*, in the centre of our Galaxy has the largest angular size in the sky among all astrophysical black holes. Its shadow, assuming no rotation, spans ~ 50 microarcsec. Resolving such…
We investigate strong field gravitational lensing by rotating Simpson-Visser black hole, which has an additional parameter ($0\leq l/2M \leq1$), apart from mass ($M$) and rotation parameter ($a$). A rotating Simpson-Visser metric correspond…
The recently released images of the supermassive black holes in the M87 galaxy and the galaxy of our own make probing black hole spacetimes and testing general relativity (GR) possible. The violation of equatorial reflection symmetry of…
In this paper we have investigated the gravitational lensing phenomenon in the strong field regime for a regular, charged, static, non-linear black hole having a electrodynamics source. We have obtained the angle of deflection and compared…
Recently, Zakharov et al. (2005) considered the possibility of evaluating the spin parameter and the inclination angle for Kerr black holes in nearby galactic centers by using future advanced astrometrical instruments. A similar approach…
In this paper we review and discuss some of the intriguing properties of the Galactic Center supermassive black hole candidate Sgr A*. Of all possible black hole sources, the event horizon of Sgr A*, subtends the largest angular scale on…
We present a new solution in Einstein's theory of relativity, found through the use of the symmetries of the Ernst equations and in particular the Harrison and Ehlers transformations. The new metric represents a Reissner-Nordstr\"om black…
Noncommutative geometry may be a starting point to a quantum gravity. We study the influence of the spacetime noncommutative parameter on the strong field gravitational lensing in the noncommutative Schwarzschild black-hole spacetime and…
The motion data of the S-stars around the Galactic center gathered in the last 28 yr imply that Sgr A* hosts a supermassive compact object of about $4\times 10^6$ $M\odot$, a result awarded with the Nobel Prize in Physics 2020. A…
General relativity has been widely tested in weak gravitational fields but still stands largely untested in the strong-field regime. According to the no-hair theorem, black holes in general relativity depend only on their masses and spins…
Near-infrared observations of stellar orbits at the Galactic Center provide conclusive evidence for a massive black hole associated with the compact radio source Sgr A*. The astrometric reference frame for these observations is tied to a…
Models postulating the existence of additional spacelike dimensions of macroscopic or even infinite size, while viewing our observable universe as merely a 3-brane living in a higher-dimensional bulk were a major breakthrough when proposed…
The star S0-2, orbiting the Galactic central massive black hole candidate Sgr A*, passed its pericenter in May 2018. This event is the first chance to detect the general relativistic (GR) effect of a massive black hole, free from…
We describe a new approach to calculating photon trajectories and gravitational lensing effects in the strong gravitational field of the Kerr black hole. These techniques are applied to explore both the imaging and spectral properties of…
An analytic extension of the Reissner-Nordstrom solution at and beyond the singularity is presented. The extension is obtained by using new coordinates in which the metric becomes degenerate at $r=0$. The metric is still singular in the new…