Related papers: Constraining Black Hole Parameters from Shadow and…
The study of radiation emitted from black hole accretion discs represents a crucial way to understand the main physical properties of these sources, and in particular the black hole spin. Beside spectral analysis, polarimetry is becoming…
We show how Event Horizon Telescope (EHT) observations of the supermassive object at the center of M87 can constrain deviations from General Relativity (GR) in a relatively model-independent way. We focus on the class of theories whose…
Accretion disks around black holes radiate a significant fraction of the rest mass of the accreting material in the form of thermal radiation from within a few gravitational radii of the black hole ($ r \lesssim 20 G M / c^{2}$). In…
We propose a new method to determine the physical parameters of Kerr black holes (namely, specific angular momentum $a$, inclination angle $i$, and distance $D$ from an observer) only from the shadow's information such as the size and…
Current models of the spectrum of X-rays reflected from accretion disks around black holes and other compact objects are commonly calculated assuming that the density of the disk atmosphere is constant within several Thomson depths from the…
We propose a simple, analytic dual-cone accretion model for horizon scale images of the cores of Low-Luminosity Active Galactic Nuclei (LLAGN), including those observed by the Event Horizon Telescope (EHT). Our underlying model is of…
The accretion disk around a black hole and its emissions play an essential role in theoretical analysis of the black hole image. In the literature, two analytical toy models of accretions are widely adopted: the spherical model and the thin…
In this paper, we consider a charged AdS/dS black hole (BH) in $R^{2}$ gravity and study its optical features, including the shadow's geometrical shape and the energy emission rate. Additionally, we look for criteria to restrict the free…
Decomposing an arbitrary electron energy distribution into sums of Maxwellian and power law components is an efficient method to calculate synchrotron emission and absorption. We use this method to study the effect of non-thermal electrons…
The measurement of relativistic effects around the galactic center may allow in the near future to strongly constrain the parameters of the supermassive black hole likely present at the galactic center (Sgr A*). As a by-product of these…
We consider the optical appearance under a thin accretion disk of a regular black hole with a central de Sitter core implementing $\mathcal{O}(l^2/r^2)$ far-corrections to the Schwarzschild black hole. We use the choice $l=0.25M$, which…
Photons emitted by light sources in the neighbourhood of a black hole can wind several times around it before fleeing towards the observer. For spherically symmetric black holes, two infinite sequences of images are created for any given…
Motivated by string theory, we constrain non-commutative black hole parameters through shadow behaviors using machine learning techniques combined by CUDA computations. To do so, we first investigate the structure of the event horizon of…
The motion of photons around the Kerr-Newman-dS black hole surrounded by quintessence and a cloud of strings is investigated. The existence of the Carter constant leads to that of unstable circular photon orbits on a two-dimensional plane…
The Event Horizon Telescope (EHT), a global very long baseline interferometry array operating at millimetre wavelengths, is spatially resolving the immediate environments of black holes for the first time. The current observations of the…
With recent advancements in observing supermassive black holes with the Event Horizon Telescope, there has been persistent exploration into what the images can reveal about fundamental physics, including space-time geometries and…
Latest advances in effective quantum gravity propose a quantum-corrected black hole solution that avoids Cauchy horizons. This paper studies the images of this black hole when illuminated by a static thin accretion disk and explores the…
In this work, we explored the Hayward black hole surrounded by a cloud of strings, with a focus on the effects of the regularization parameter $l$ and the string cloud parameter $a$ on its observational properties and quasinormal modes…
The circular polarization of black hole accretion flows can encode properties of the underlying magnetic field structure. Using general relativistic magnetohydrodynamics (GRMHD) simulations, we study the imprint of magnetic field geometry…
In this paper, we study circular orbits, effective potential, and thin-accretion disk of a black hole in symmergent gravity within the Novikov-Thorne model in a way including the energy flux and temperature distribution. We determine bounds…