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Following up on a recent analysis by Psaltis et al. [Phys. Rev. Lett. 125, 141104 (2020)], we show that the observed shadow size of M87$^*$ can be used to unambiguously and robustly constrain the black hole geometry in the vicinity of the…

General Relativity and Quantum Cosmology · Physics 2021-10-13 Sebastian H. Völkel , Enrico Barausse , Nicola Franchini , Avery E. Broderick

In light of the Event Horizon Telescope (EHT) images of the supermassive black holes $\textrm{Sgr A}^\star$ and $\textrm{M87}^\star$, we explore a potential supersymmetry suspicion within the observational data. Specifically, we investigate…

High Energy Physics - Theory · Physics 2024-09-05 L. Chakhchi , H. El Moumni , K. Masmar

We investigate strong gravitational lensing by two static black hole models (Model-1 and Model-2) within the Effective Quantum Gravity (EQG) framework, characterized by mass $M$ and parameter $\zeta$. For $\zeta = 0$, they reduce to the…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-17 Yiyang Wang , Amnish Vachher , Qiang Wu , Tao Zhu , Sushant G. Ghosh

Black holes with dyonic charges in Einstein-Maxwell-dilaton-axion supergravity theory are revisited in the context of black hole shadows. We consider static as well as rotating (namely the dyonic Kerr-Sen) black holes. The matter…

General Relativity and Quantum Cosmology · Physics 2023-08-08 Soumya Jana , Sayan Kar

Observations of the black hole shadow of supermassive black holes, such as Sagittarius A* at the center of our Milky Way galaxy, allow us to study the properties of black holes and the nature of strong-field gravity. According to the Kerr…

General Relativity and Quantum Cosmology · Physics 2018-11-14 Dimitry Ayzenberg , Nicolas Yunes

Recent observations of the supermassive black holes M87* and Sgr A* by the Event Horizon Telescope (EHT) have opened new avenues for testing gravity theories through black hole shadow observables. These observations offer a means to…

General Relativity and Quantum Cosmology · Physics 2025-05-05 Mohsen Fathi , Yassine Sekhmani

Due to the gravitational lensing effect, a black hole casts a shadow larger than its horizon over a bright background, and the shape and size can be calculated. The Event Horizon Telescope collaboration has produced the first direct image…

General Relativity and Quantum Cosmology · Physics 2021-09-28 Rahul Kumar , Balendra Pratap Singh , Md Sabir Ali , Sushant G. Ghosh

Motivated by the first image of a black hole captured by the Event Horizon Telescope (EHT), there has been a surge of research using observations of black hole shadows to test theories of gravity. In this paper, we carry out a study related…

General Relativity and Quantum Cosmology · Physics 2024-08-06 Qi Sun , Yu Zhang , Chen-Hao Xie , Qi-Quan Li

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…

Astrophysics of Galaxies · Physics 2015-06-19 F. H. Vincent , W. Yan , O. Straub , A. A. Zdziarski , M. A. Abramowicz

Testing gravity theory in the strong field region becomes a reality due to the observations of gravitational waves and black hole shadows. In this paper, we discuss how to constrain the possible deviations of the classical general…

General Relativity and Quantum Cosmology · Physics 2019-09-10 S. X. Tian , Zong-Hong Zhu

With the recent release of the black hole image of Sgr A* alongside the earlier image of M87*, one can now really hope to acquire a better understanding of the gravitational physics at the horizon scale. In this paper, we investigate the…

General Relativity and Quantum Cosmology · Physics 2022-10-05 Indrani Banerjee , Subhadip Sau , Soumitra SenGupta

The Event Horizon Telescope (EHT) Collaboration produced the first image of the apparent shadow of the central black hole of Sagittarius\,A$^*$ (\sgra). \sgra source structure varies significantly on timescales shorter than the duration of…

High Energy Astrophysical Phenomena · Physics 2026-01-26 Braden J. Marazzo-Nowicki , Paul Tiede , Dominic O. Chang , Daniel C. M. Palumbo , Michael D. Johnson

The Galactic Center black hole Sagittarius A* (Sgr A*) is a prime observing target for the Event Horizon Telescope (EHT), which can resolve the 1.3 mm emission from this source on angular scales comparable to that of the general…

In this paper, the shadows cast by non-rotating and rotating modified gravity black holes are investigated. In addition to the black hole spin parameter $a$ and the inclination angle $\theta$ of observer, another parameter $\alpha$…

General Relativity and Quantum Cosmology · Physics 2019-04-08 Hui-Min Wang , Yu-Meng Xu , Shao-Wen Wei

We show that the observed angular diameter of the shadow of the ultra compact object Sgr A*, favours the existence of an extra spatial dimension. This holds irrespective of the nature of the ultra compact object, i.e., whether it is a…

General Relativity and Quantum Cosmology · Physics 2022-12-07 Indrani Banerjee , Sumanta Chakraborty , Soumitra SenGupta

The Event Horizon Telescope (EHT) has imaged the shadow of the supermassive black hole in M87. A library of general relativistic magnetohydrodynamics (GMRHD) models was fit to the observational data, providing constraints on black hole…

High Energy Astrophysical Phenomena · Physics 2021-06-09 Freek Roelofs , Christian M. Fromm , Yosuke Mizuno , Jordy Davelaar , Michael Janssen , Ziri Younsi , Luciano Rezzolla , Heino Falcke

Recently there has been a surge of interest in regularizing, a $ D \to 4 $ limit of, the Einstein-Gauss-Bonnet (EGB) gravity, and the resulting regularized $4D$ EGB gravity has nontrivial dynamics. The theory admits spherically symmetric…

General Relativity and Quantum Cosmology · Physics 2020-07-28 Rahul Kumar , Sushant G. Ghosh

The Event Horizon Telescope has produced resolved images of the supermassive black holes Sgr A* and M87*, which present the largest shadows on the sky. In the next decade, technological improvements and extensions to the array will enable…

The recent time witnessed a surge of interest in strong gravitational lensing by black holes is due to the Event Horizon Telescope (EHT) results, which suggest comparing the black hole lensing in both general relativity and heterotic string…

General Relativity and Quantum Cosmology · Physics 2021-03-25 Sushant G. Ghosh , Rahul Kumar , Shafqat Ul Islam

Four spherically symmetric but non-asymptotically flat black hole solutions surrounded with spherical dark matter distribution perceived under the minimal length scale effect is derived via the generalized uncertainty principle. Here, the…

General Relativity and Quantum Cosmology · Physics 2023-12-08 Ali Övgün , Lemuel John F. Sese , Reggie C. Pantig