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Using the general parametrization of spherically symmetric and asymptotically flat black holes in arbitrary metric theories of gravity and implying that: a) the post-Newtonian constraints are taken into account and b) basic astrophysically…

General Relativity and Quantum Cosmology · Physics 2023-08-10 R. A. Konoplya , A. Zhidenko

In previous work we have developed a model-independent, effective description of quantum deformed, spherically symmetric and static black holes in four dimensions. The deformations of the metric are captured by two functions of the physical…

General Relativity and Quantum Cosmology · Physics 2024-12-19 Manuel Del Piano , Stefan Hohenegger , Francesco Sannino

Alternative theories of gravity and the parameterized deviation approach allow black hole solutions to have additional parameters beyond mass, charge and angular momentum. Matter fields could be, in principle, affected by the additional…

General Relativity and Quantum Cosmology · Physics 2020-04-21 Renan B. Magalhães , Luiz C. S. Leite , Luís C. B. Crispino

Grey-body factors are not only essential ingredients for computing the intensity of Hawking radiation, but also serve as characteristics of black hole's geometry that are closely related to their quasinormal modes. Importantly, they tend to…

General Relativity and Quantum Cosmology · Physics 2026-02-16 Roman A. Konoplya , Thomas D. Pappas

We present the shape of the black hole shadow on the standard background screen as it is registered by the distant observer. The screen is an infinite plane, emitting the quanta uniformly distributed to a hemisphere. The source of emission…

General Relativity and Quantum Cosmology · Physics 2018-02-14 Serge V. Repin , Dmitry A. Kompaneets , Igor D. Novikov , Valeriya A. Mityagina

We study the shadow of rotating charge black holes in the presence of quintessence. The shadow of a rotating black hole is a distorted circle and in our study, we find that the shape and size of the black hole shadow depend upon four…

General Relativity and Quantum Cosmology · Physics 2022-05-05 Balendra Pratap Singh

The astrophysical consequences of the presence of a quintessence scalar field on the evolution of the horizon and on the accretion disk surrounding a static black hole, in the Scalar-Vector-Tensor version of Modified Gravity (MOG), are…

General Relativity and Quantum Cosmology · Physics 2023-09-15 Haidar Sheikhahmadi , Saheb Soroushfar , S. N. Sajadi , Tiberiu Harko

The Event Horizon Telescope (EHT) Collaboration has recently published the first horizon-scale images of the supermassive black holes M87* and Sgr A* and provided some first information on the physical conditions in their vicinity. The…

High Energy Astrophysical Phenomena · Physics 2023-11-20 Kotaro Moriyama , Alejandro Cruz-Osorio , Yosuke Mizuno , Christian M. Fromm , Antonios Nathanail , Luciano Rezzolla

This study explores spherically symmetric non-linear electrodynamics black holes and their effects on light propagation. We derive the governing metric, revealing radial coordinate dynamics within the event horizon. We analyze photon…

General Relativity and Quantum Cosmology · Physics 2024-02-06 Akhil Uniyal , Sayan Chakrabarti , Mohsen Fathi , Ali Övgün

In the static and infalling spherical-shell models of optically thin accretion on Schwarzschild black hole, the formulas for the integrated intensities observed by a distant observer are derived, and by taking the monochromatic emission…

General Relativity and Quantum Cosmology · Physics 2025-06-19 Bofeng Wu , En-Wei Liang , Xiao Zhang

Motivated by the work of Cardoso et al. [Phys. Rev. D 105 (2022) 6, L061501, https://doi.org/10.1103/PhysRevD.105.L061501] on black holes in galaxies, we derive a new black hole solution surrounded by a Dekel-Zhao (DZ) dark matter profile.…

General Relativity and Quantum Cosmology · Physics 2025-03-25 Ali Övgün , Reggie C. Pantig

The projection effect of an anisotropic accretion disk causes its electromagnetic radiation to depend on the emission angle. Although this dependency has the potential to influence the observational characteristics of black holes, it has…

General Relativity and Quantum Cosmology · Physics 2024-09-10 Dan Li , Shiyang Hu , Chen Deng , Xin Wu

Black holes in General Relativity are described by space-time metrics that are simpler in comparison to non-vacuum compact objects. However, given the universality of the gravitational pull, it is expected that dark matter accumulates…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Caio F. B. Macedo , João Luís Rosa , Diego Rubiera-Garcia

In this study, we investigate the signatures of a non-commutative black hole solution. Initially, we calculate the thermodynamic properties of the system, including entropy, heat capacity, and Hawking radiation. For the latter quantity, we…

General Relativity and Quantum Cosmology · Physics 2024-08-29 A. A. Araújo Filho , J. R. Nascimento , A. Yu. Petrov , P. J. Porfírio , Ali Övgün

We establish a thermodynamic-optical duality that directly bridges the semiclassical quantum evaporation of black holes with their classical macroscopic geometry. By employing a diffeomorphic inversion, we re-parameterize the intrinsic…

General Relativity and Quantum Cosmology · Physics 2026-04-27 Nikko John Leo S. Lobos , Emmanuel T. Rodulfo

We calculate the emission of gravitational waves, gravitons, photons and neutrinos from a perturbed Schwarzschild blackhole (BH). The perturbation can be due to either classical or quantum sources and therefore the injected energy can be…

High Energy Physics - Theory · Physics 2019-12-11 Ram Brustein , Yotam Sherf

We study the scattering of light-like geodesics and massless scalar waves by a static Konoplya-Zhidenko black hole, considering the case that the parametrized black hole solution contains a single deformation parameter. By performing a…

General Relativity and Quantum Cosmology · Physics 2023-04-25 Renan B. Magalhães , Luiz C. S. Leite , Luís C. B. Crispino

We present estimates for the number of supermassive black holes (SMBHs) for which the next-generation Event Horizon Telescope (ngEHT) can identify the black hole ``shadow,'' along with estimates for how many black hole masses and spins the…

Black hole shadow and gravitational lensing play important roles in testing gravitational theories in the strong field regime. As the first-order modifications from quantum gravity, the nonlocality can be manifested by black hole shadow and…

General Relativity and Quantum Cosmology · Physics 2022-06-24 Qi-Ming Fu , Shao-Wen Wei , Li Zhao , Yu-Xiao Liu , Xin Zhang

We derive a geometrical version of the Regge-Wheeler and Zerilli equations, which allows us to study gravitational perturbations on an arbitrary spherically symmetric slicing of a Schwarzschild black hole. We explain how to obtain the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Olivier Sarbach , Manuel Tiglio