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We study the shadow of a charged rotating black hole in $f(R)$ gravity. This black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and $R_{0}$ which is proportional to cosmological constant. We analyze the image of the…

General Relativity and Quantum Cosmology · Physics 2022-10-06 Sara Dastan , Reza Saffari , Saheb Soroushfar

The images of supermassive black holes surrounded by optically-thin, radiatively-inefficient accretion flows, like those observed with the Event Horizon Telescope, are characterized by a bright ring of emission surrounding the black-hole…

High Energy Astrophysical Phenomena · Physics 2023-02-01 Ziri Younsi , Dimitrios Psaltis , Feryal Özel

Explicitly covariant analytical expressions are derived that describe the boundaries of shadows cast by massive particles scattered by a gravitating object. This covers scenarios with particles having effectively variable mass, such as…

General Relativity and Quantum Cosmology · Physics 2023-12-15 Kirill Kobialko , Igor Bogush , Dmitri Gal'tsov

In the Einstein-bumblebee gravity, the Lorentz symmetry is spontaneously broken by a vector field. In this paper, we attempt to test the Lorentz symmetry via the observation of the shadow cast by the Kerr-like black hole with or without…

General Relativity and Quantum Cosmology · Physics 2021-06-29 Hui-Min Wang , Shao-Wen Wei

We demonstrate that the location of a stable photon sphere (PS) in a compact object is not always an edge such as the inner boundary of a black hole shadow, whereas the location of an unstable PS is known to be the shadow edge notably in…

General Relativity and Quantum Cosmology · Physics 2022-06-08 Ryuya Kudo , Hideki Asada

In this paper, we study the influence of the axion-plasmon, as proposed in (Phys. Rev. Lett. 120, 181803 (2018)) on the optical properties of the Schwarzschild black hole. Our aim is to provide a test to detect the effects of a fixed axion…

General Relativity and Quantum Cosmology · Physics 2021-09-22 Farruh Atamurotov , Kimet Jusufi , Mubasher Jamil , Ahmadjon Abdujabbarov , Mustapha Azreg-Aïnou

We set out to bridge the gap between regular black-hole spacetimes and observations of a black-hole shadow by the Event Horizon Telescope. We explore modifications of spinning and non-spinning black-hole spacetimes inspired by…

General Relativity and Quantum Cosmology · Physics 2019-06-19 Aaron Held , Roman Gold , Astrid Eichhorn

We study gravitational lensing when plasma surrounds the lens. An extra deflection angle is induced by the plasma in addition to the deflection generated by gravity. An inhomogeneous plasma distribution generates a greater effect than a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Xinzhong Er , Shude Mao

In this paper, we are interested in a model of exact asymptotically flat charged hairy black holes in the background of dilaton potential. We study the weak gravitational lensing in the spacetime of hairy black hole in Einstein-Maxwell…

General Relativity and Quantum Cosmology · Physics 2019-08-30 Wajiha Javed , Jameela Abbas , Ali Övgün

We investigate the deflection angle in a strong deflection limit for a marginally unstable photon sphere in a general asymptotically flat, static and spherically symmetric spacetime under some assumptions to calculate observables. The…

General Relativity and Quantum Cosmology · Physics 2020-11-12 Naoki Tsukamoto

We investigate the temperature, photon and shadow radii, quasinormal modes (QNMs), time domain profiles, greybody factors, emission rates and topological characteristics of deformed black holes, focusing on the effects of the deformation…

High Energy Physics - Theory · Physics 2025-08-26 Dhruba Jyoti Gogoi , Jyatsnasree Bora , Filip Studnička , H. Hassanabadi

This study explores the impact of antisymmetric tensor effects on spherically symmetric black holes, investigating photon spheres, shadows, emission rate and quasinormal frequencies in relation to a parameter which triggers the Lorentz…

General Relativity and Quantum Cosmology · Physics 2024-05-03 A. A. Araújo Filho , J. A. A. S. Reis , H. Hassanabadi

In this paper we derive exact analytical formulas for the evolution of the photon sphere and for the angular radius of the shadow in a special Vaidya spacetime. The Vaidya metric describes a spherically symmetric object that gains or loses…

General Relativity and Quantum Cosmology · Physics 2022-04-01 Jay Solanki , Volker Perlick

Dark matter sectors with hidden interactions have been of much interest in recent years. These frameworks include models of millicharged particles as well as dark sector bound states, whose constituents have electromagnetic gauge…

High Energy Physics - Phenomenology · Physics 2022-03-30 Lalit S. Bhandari , Arun M. Thalapillil

Due to the exponential high gravitational red shift near the event horizon of a black hole, it might appears that the Hawking radiation would be highly sensitive to some unknown high energy physics. To study possible deviations from the…

General Relativity and Quantum Cosmology · Physics 2017-11-08 Jun Tao , Peng Wang , Haitang Yang

We investigate the shadow of Kerr-Bertotti-Robinson black holes (KBRBHs), which have a deviation parameter $B$ that captures the effect of an external magnetic field on the spacetime geometry. These spacetimes of Petrov type $D$ are…

General Relativity and Quantum Cosmology · Physics 2026-01-28 Heena Ali , Sushant G. Ghosh

In this paper, we examine the weak deflection angle and greybody bound for magnetized regular black hole.$~$ For this purpose, we apply the Gauss-Bonnet theorem on the black hole and obtain the deflection angle in plasma and non-plasma…

General Relativity and Quantum Cosmology · Physics 2022-05-06 Wajiha Javed , Sibgha Riaz , Ali Övgün

We investigate the deflection of light around a BTZ-ModMax black hole, focusing on the influence of the ModMax parameter and the cosmological constant. The trajectories of massless particles are explored through an analysis of null…

General Relativity and Quantum Cosmology · Physics 2025-12-15 Shubham Kala

We investigate the impact of the axionic coupling parameter on the bending angle of light and the shadow cast by slowly rotating black holes in Chern-Simons modified gravity. We utilize the Ishihara \etal method to derive the deflection…

General Relativity and Quantum Cosmology · Physics 2023-06-16 Nashiba Parbin , Dhruba Jyoti Gogoi , Umananda Dev Goswami

We analytically investigate the shadows cast by rotating black holes in the asymptotically safe gravity (ASG) by deriving complete null geodesics and observables using the Hamilton-Jacobi equation and Carter separable method. It turns out…

General Relativity and Quantum Cosmology · Physics 2020-07-13 Rahul Kumar , Balendra Pratap Singh , Sushant G. Ghosh