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In order to better describe gravitational phenomena on both very small and cosmological scales, there have been constant attempts to generalize and expand the theory of General Relativity (GR) since its inception. The Einstein Gauss Bonnet…

General Relativity and Quantum Cosmology · Physics 2025-11-04 Sara Saghafi , Kourosh Nozari , Maryam Kaveh

An Extended Uncertainty Principle inspired Schwarzschild metric that allows for large scale modifications to gravitation is presented. At a new fundamental length scale $\Ls$, the usual black hole characteristics (horizon radius, ISCO, and…

General Relativity and Quantum Cosmology · Physics 2018-12-24 J. R. Mureika

In this work, we explored the effect of the fuzzy dark matter (FDM) (or wave dark matter) halo on a supermassive black hole (SMBH). Such a dark matter introduces a soliton core density profile, and we treat it ideally as a spherical…

General Relativity and Quantum Cosmology · Physics 2023-01-31 Reggie C. Pantig , Ali Övgün

Poincar\'e Gauge's theory of gravity is the most noteworthy alternative extension of general relativity that has a correspondence between spin and spacetime geometry. In this paper, we use Reissner-Nordstrom-de Sitter and anti-de Sitter…

General Relativity and Quantum Cosmology · Physics 2022-12-23 Reggie C. Pantig , Ali Övgün

We study the shadows of four dimensional black holes in M-theory inspired models. We first inspect the influence of M2-branes on such optical aspects for non-rotating solutions. In particular, we show that the M2-brane number can control…

High Energy Physics - Theory · Physics 2021-04-21 A. Belhaj , M. Benali , A. El Balali , W. El Hadri , H. El Moumni , E. Torrente-Lujan

This research delves into the optical characteristics of stationary, spherically symmetric black holes. These black holes follow the Konoplya-Zhidenko deformation rule in arbitrary gravity theories. This research finds that the effects of…

General Relativity and Quantum Cosmology · Physics 2025-05-28 Qiao Yue , Zhaoyi Xu , Meirong Tang

Motivated by M-theory compactifications, we investigate optical properties of black holes in the Starobinsky-Bel-Robinsion gravity. Precisely, we study the shadows and the deflection angle of light rays by non-rotating and rotating black…

High Energy Physics - Theory · Physics 2023-04-11 A. Belhaj , H. Belmahi , M. Benali , Y. Hassouni , M. B. Sedra

The Event Horizon Telescope (EHT) observation unveiled the first image of supermassive black hole Sgr A* showing a shadow of diameter $\theta_{sh}= 48.7 \pm 7\,\mu$as with fractional deviation from the Schwarzschild black hole shadow…

General Relativity and Quantum Cosmology · Physics 2022-11-10 Rahul Kumar Walia , Sushant G Ghosh , Sunil D Maharaj

With the imaging and characterization of the horizon-scale images of M87* and Sgr A* by the Event Horizon Telescope (EHT), it has become possible to resolve the near-horizon region of astrophysical black holes. As a result, there has been…

High Energy Astrophysical Phenomena · Physics 2023-07-31 Avery E. Broderick , Kiana Salehi , Boris Georgiev

Scalar-tensor-vector gravity, also known as modified gravity (MOG), has emerged as an alternative to General Relativity (GR). It aims to explain astrophysical phenomena without invoking dark matter. The S-stars orbiting the supermassive…

General Relativity and Quantum Cosmology · Physics 2026-05-21 Ioannis Liodis , Gernot Heissel , Rita Mastroioanni , Jai Grover , Dario Izzo

This thesis embarks on a comprehensive investigation of modified gravity theories and their implications on the properties of compact objects. Our primary objective is to shed light on the fundamental nature of gravity by exploring…

General Relativity and Quantum Cosmology · Physics 2024-06-25 Rajes Ghosh

The need for a consistent quantum evolution for black holes has led to proposals that their semiclassical description is modified not just near the singularity, but at horizon or larger scales. If such modifications extend beyond the…

High Energy Astrophysical Phenomena · Physics 2018-04-25 Steven B. Giddings , Dimitrios Psaltis

A general covariant Einstein-Gauss-Bonnet Gravity in Four-Dimensional (4D EGB) spacetime is shown to bypass Lovelock's theorem and is free from Ostrogradsky instability. Meanwhile, the bumblebee theory is a vector-tensor theory. It extends…

General Relativity and Quantum Cosmology · Physics 2024-09-11 Misba Afrin , Sushant G. Ghosh , Anzhong Wang

In this paper, we study the shadow cast by two types of charged and slowly rotating black holes in Eisntein-aether theory of gravity. This two types of black holes are corresponding to two specific combinations of the coupling constants of…

General Relativity and Quantum Cosmology · Physics 2019-09-04 Tao Zhu , Qiang Wu , Mubasher Jamil , Kimet Jusufi

We study, for the first time, the shadow of the supermassive black hole Sgr A$^{*}$ at the center of the Milky Way in dark matter halos. For the Cold Dark Matter and Scalar Field Dark Matter models considered in this work, the apparent…

General Relativity and Quantum Cosmology · Physics 2018-07-25 Xian Hou , Zhaoyi Xu , Ming Zhou , Jiancheng Wang

In this paper, we introduce a new approach to study the behavior of the photon sphere and shadow radius. Our method uses extended gravitational decoupling and reveals two important analytic results. First, the additional matter field alters…

General Relativity and Quantum Cosmology · Physics 2024-06-04 Vitalii Vertogradov , Ali Övgün

We calculate the characteristics of the "black hole shadow" for a rotating, neutral black hole in fourth-order conformal Weyl gravity. It is shown that the morphology is not significantly affected by the underlying framework, except for…

General Relativity and Quantum Cosmology · Physics 2018-04-13 Jonas R. Mureika , Gabriele U. Varieschi

This work investigates the optical properties of a static, spherically symmetric, electrically charged black hole in f(R) gravity coupled to Euler-Heisenberg(EH) nonlinear electrodynamics(NLED). By analyzing photon trajectories in this…

General Relativity and Quantum Cosmology · Physics 2026-01-16 Khadije Jafarzade , Saira Yasmin , Mubasher Jamil

This study probes spacetime solutions within Einstein-Bumblebee gravity, a modified gravitational framework incorporating spontaneous Lorentz symmetry violation through a vector field mechanism. By introducing a cosmological constant into…

General Relativity and Quantum Cosmology · Physics 2025-08-04 Reggie C. Pantig , Shubham Kala , Ali Övgün , Nikko John Leo S. Lobos

In this paper, we study charged black hole solutions in 4-dimensional Einstein-Gauss-Bonnet gravity combined with ModMax nonlinear electrodynamics. This is a conformally invariant extension of Maxwell theory that effectively describes…

General Relativity and Quantum Cosmology · Physics 2026-01-07 Bilel Hamil
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