相关论文: Lensing By Sgr A* as a Probe of Modified Gravity
This work is devoted to the study of the optical properties of the charged-rotating-NUT-Kiselev (CRNK) black hole in the Rastall theory of gravity. By investigating the motion of photons in the CRNK black hole spacetime in the Rastall…
A Kerr black hole with mass parameter m and angular momentum parameter a acting as a gravitational lens gives rise to two images in the weak field limit. We study the corresponding magnification relations, namely the signed and absolute…
We introduce a modification in the energy-momentum conservation violating Rastall's theory of gravity and obtain a Reissner-Nordstr\"om-type black hole solution in spacetime surrounded by a cloud of strings and charge fields. We examine the…
This paper investigates the shadow images of rotating charged black holes in Kalb-Ramond (KR) gravity, using an accretion disk that is both optically and geometrically thin and located on the equatorial plane as the light source model. The…
Recently a short scale modified black hole metric, known as holographic metric, has been proposed in order to capture the self-complete character of gravity. In this paper we show that such a metric can reproduce some geometric features…
With the observed data of the S2 orbit around the black hole Sgr A$^*$ and the Markov Chain Monte Carlo method, we make a constraint on parameters of a disformal Schwarzschild black hole in quadratic degenerate higher-order scalar-tensor…
The prediction of spacetime singularities, regions of infinite curvature where classical physics breaks down, is one of the most profound challenges in General Relativity (GR). In particular, black hole solutions such as the Schwarzschild…
Schwarzschild black holes can produce strong gravitational lensing. The relativistic images are produced due to bending of light around the black hole. We propose a model equation to study the strong gravitational lensing. The model…
We report on the results of new simulations of near-infrared (NIR) observations of the Sagittarius A* (Sgr A*) counterpart associated with the super-massive black hole at the Galactic Center. The observations have been carried out using the…
It has been suggested that there is possibly a class of stellar-mass black holes (BHs) residing near (distance $\le 10^3 M$) the galactic center massive black hole, Sgr A*. Possible formation scenarios include the mass segregation of…
Precision measurements of the stars in short-period orbits around the supermassive black hole at the Galactic Center are now being used to constrain general relativistic effects, such as the gravitational redshift and periapse precession.…
The Event Horizon Telescope (EHT) recently released an image of the supermassive black hole Sgr A* showing an angular shadow diameter $d_{sh}= 48.7 \pm 7\,\mu$as and Schwarzschild shadow deviation $\delta =…
Recent observations of the Milky-way galactic center at various frequencies suggest a supermassive compact object. Generally, that supermassive compact object is assumed to be a `Black Hole', having more than four million solar masses. In…
We consider exact solutions of Einstein equations defining static black holes parametrized by off-diagonal metrics which by anholonomic mappings can be equivalently transformed into some diagonal metrics with coefficients being very similar…
Our Galaxy hosts a very massive object at its centre, often referred to as the supermassive black hole Sgr A*. Its gravitational tidal field is so intense that can strip apart a binary star passing its vicinity and accelerate one of the…
We study Bardeen-like regular black holes without Cauchy horizons via gravitational lensing. In the weak field, the deflection angle receives a positive $\ell$-dependent correction, producing a slightly larger Einstein ring. For the galaxy…
The black hole in the center of the Milky Way has been observed and modeled intensely during the last decades. It is also the prime target of a number of new experiments that aim to zoom into the vicinity of its horizon and reveal the inner…
From the Reissner-Nordstrom metric we obtain the higher-order terms for the deflection of light around a massive-charged black hole using the Lindstedt-Poincar\'e method to solve the equation of motion of a photon around the compact object.…
The center of our galaxy hosts Sagittarius~A*, a supermassive compact object of $\sim 4.3\times 10^6$ solar masses, usually associated with a black hole. Nevertheless, black holes possess a central singularity, considered unphysical, and an…
We report new infrared measurements of the supermassive black hole at the Galactic Center, Sgr A*, over a decade that was previously inaccessible at these wavelengths. This enables a variability study that addresses variability timescales…