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The initial data from the Event Horizon Telescope (EHT) on M87$^*$, the supermassive black hole at the center of the M87 galaxy, provide direct observational information on its mass, spin, and accretion disk properties. A combination of the…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-12 Hooman Davoudiasl , Peter B. Denton

The Event Horizon Telescope, a global submillimeter wavelength very long baseline interferometry array, produced the first image of supermassive black hole M87* showing a ring of diameter $\theta_d= 42\pm 3\,\mu$as, inferred a black hole…

General Relativity and Quantum Cosmology · Physics 2020-06-18 Rahul Kumar , Amit Kumar , Sushant G. Ghosh

We find a Kerr-like black hole solution-a rotating Bumblebee black hole (RBBH) with a Lorentz-violating parameter $\ell$ and examine the strong lensing by it. The parameter $\ell$ changes the event horizon radius and photon sphere,…

General Relativity and Quantum Cosmology · Physics 2025-09-03 Arun Kumar , Shafqat Ul Islam , Sushant G. Ghosh

We consider a Lorentz violating non-commutating Kerr-like spacetime and studied the superradiance effect and the shadow cast by the back hole. We extensively study the different aspects of the black hole associated with a generalized…

General Relativity and Quantum Cosmology · Physics 2022-04-22 Sohan Kumar Jha , Anisur Rahaman

We compare and contrast gravitational lensing, in the strong-field limit, by photon sphere in spherically symmetric regular electrically charged (REC) black holes ($0<b\leq b_E$) and with those by corresponding REC no-horizon spacetimes…

General Relativity and Quantum Cosmology · Physics 2022-10-21 Jitendra Kumar , Shafqat Ul Islam , Sushant G. Ghosh

The existence of curvature singularities and the information and firewall paradoxes are significant problems for the conventional black hole model. The black mirror provides a CPT-symmetric alternative to the classical description. We show…

General Relativity and Quantum Cosmology · Physics 2026-01-21 Pau Amaro Seoane

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

We propose a new imaging technique for radio and optical/infrared interferometry. The proposed technique reconstructs the image from the visibility amplitude and closure phase, which are standard data products of short-millimeter very long…

While supermassive black hole masses have been cataloged across cosmic time, only a few dozen of them have robust spin measurements. By extending and improving the existing Event Horizon Telescope (EHT) array, the next-generation Event…

High Energy Astrophysical Phenomena · Physics 2022-11-09 Angelo Ricarte , Paul Tiede , Razieh Emami , Aditya Tamar , Priyamvada Natarajan

Event Horizon Telescope (EHT) observations at 230 GHz are combined with Very Long Baseline Interferometry (VLBI) observations at 86 GHz and high resolution Hubble Space Telescope optical observations in order to constrain the broadband…

Astrophysics of Galaxies · Physics 2017-12-13 Brian Punsly

The Event Horizon Telescope recently captured images of the supermassive black hole in the center of the M87 galaxy, which show a ring-like emission structure with the South side only slightly brighter than the North side. This relatively…

High Energy Astrophysical Phenomena · Physics 2022-01-19 Lia Medeiros , Chi-Kwan Chan , Ramesh Narayan , Feryal Ozel , Dimitrios Psaltis

The Event Horizon Telescope has released polarized images of the supermassive black holes Messier 87* (M87*) and Sagittarius A* (Sgr A*) accretion disks. As more images are produced, our understanding of the average polarized emission from…

High Energy Astrophysical Phenomena · Physics 2024-12-10 Daniel C. M. Palumbo

There are now multiple direct probes of the region near black hole horizons, including direct imaging with the Event Horizon Telescope (EHT). As a result, it is now of considerable interest to identify what aspects of the underlying…

General Relativity and Quantum Cosmology · Physics 2023-11-06 Kiana Salehi , Avery Broderick , Boris Georgiev

We show that very-long-baseline-interferometry (VLBI) observations of supermassive black holes will allow us to test the fundamental principles of General Relativity (GR). GR is based on the universality of gravity and Einstein's…

General Relativity and Quantum Cosmology · Physics 2023-12-18 Joseph P Johnson , Susmita Jana , S. Shankaranarayanan

The recent observation of the shadow of the supermassive compact object M87$^*$ by the Event Horizon Telescope (EHT) collaboration has opened up a new window to probe the strong gravity regime. In this paper, we study shadows cast by two…

General Relativity and Quantum Cosmology · Physics 2021-07-07 Rajibul Shaikh , Kunal Pal , Kuntal Pal , Tapobrata Sarkar

Using very long baseline interferometry, the Event Horizon Telescope (EHT) collaboration has resolved the shadows of two supermassive black holes. Model comparison is traditionally performed in image space, where imaging algorithms…

Inspired by the two different dark matter frameworks that were studied recently: one that arises from the non-local effects of entanglement entropy as emergent gravity (characterized by the parameter $\xi(M)$, and zero-point scale length…

General Relativity and Quantum Cosmology · Physics 2024-06-11 Reggie C. Pantig

The advent of the Event Horizon Telescope (EHT), a millimeter-wave very-long baseline interferometric array, has enabled spatially-resolved studies of the sub-horizon-scale structure for a handful of supermassive black holes. Among these,…

High Energy Astrophysical Phenomena · Physics 2014-03-05 Avery E. Broderick , Tim Johannsen , Abraham Loeb , Dimitrios Psaltis

We report our independent image reconstruction of the M 87 from the public data of the Event Horizon Telescope Collaborators (EHTC). Our result is different from the image published by the EHTC. Our analysis shows that (a) the structure at…

High Energy Astrophysical Phenomena · Physics 2022-07-06 Makoto Miyoshi , Yoshiaki Kato , Junichiro Makino

In this paper, we investigate the properties of black holes within the framework of multi-fractional theories of gravity, focusing on the effects of q-derivatives and weighted derivatives. These modifications, which introduce…

General Relativity and Quantum Cosmology · Physics 2025-06-03 Reggie C. Pantig