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The apparent shadow of a black hole provides one of the most direct probes of strong-field general relativity. While the shadow size in asymptotically flat spacetimes is well understood, the influence of cosmic expansion on its apparent…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Debarshi Mukherjee

Recently it has been argued that the phantom thin-shell wormholes matched with the Schwarzschild space-time near the Schwarzschild radius ring like Schwarzschild black holes at early times, but differently at late times (arXiv:1602.07309).…

General Relativity and Quantum Cosmology · Physics 2016-12-30 R. A. Konoplya , A. Zhidenko

Cosmic voids are increasingly recognized as a promising tool for cosmological exploration. Their distribution and density profiles are highly responsive to alterations in gravitational theories, along with the influences of dark energy and…

General Relativity and Quantum Cosmology · Physics 2025-08-26 A. Errehymy , S. Hansraj

We obtain the shadow cast induced by the rotating black hole with an anisotropic matter. A Killing tensor representing the hidden symmetry is derived explicitly. The existence of separability structure implies a complete integrability of…

General Relativity and Quantum Cosmology · Physics 2021-03-24 Bum-Hoon Lee , Wonwoo Lee , Yun Soo Myung

In this article, we study the possibility of sustaining a static and spherically symmetric traversable wormhole geometries admitting conformal motion in Einstein gravity, which presents a more systematic approach to search a relation…

General Relativity and Quantum Cosmology · Physics 2017-02-01 Piyali Bhar , Farook Rahaman , Tuhina Manna , Ayan Banerjee

Black hole shadows and photon spheres offer valuable tools for investigating black hole properties. Recent observations by the Event Horizon Telescope Collaboration have confirmed the existence of rotating black holes. Black hole parameters…

General Relativity and Quantum Cosmology · Physics 2024-11-26 Vitalii Vertogradov , Ali Övgün , Reggie C. Pantig

The simplistic model of the classical spacetime foam is considered, which consists of static wormholes embedded in Minkowski spacetime. We explicitly demonstrate that such a foam structure leads to a topological bias of point-like sources…

Astrophysics · Physics 2008-11-26 A. A. Kirillov , E. P. Savelova

In this paper, we calculate the weak deflection angle by Casimir wormhole and its shadow. To do so, we derive the Gaussian optical curvature and use the Gauss-Bonnet theorem. Then we find the deflection angle by Casimir wormhole in weak…

General Relativity and Quantum Cosmology · Physics 2021-01-13 Wajiha Javed , Ali Hamza , Ali Övgün

This article deals with the study of some properties of the static and rotating black holes in Kalb-Ramond gravity in four dimensional spacetime. First, we discuss the action of the corresponding theory and the static black hole metric.…

General Relativity and Quantum Cosmology · Physics 2023-10-20 M. Zubair , Muhammad Ali Raza , Eiman Maqsood

The co-varying physical couplings (CPC) framework states that physical parameters like the speed of light in vacuum $c$, the Newtonian constant $G$, and the cosmological constant $\Lambda$ could indeed vary with the spacetime coordinates…

General Relativity and Quantum Cosmology · Physics 2023-10-18 R. R. Cuzinatto , C. A. M. de Melo , Juliano C. S. Neves

We explore the possibility of formation of a traversable wormhole in General Relativity supported by particle creation mechanism. The repulsive back-reaction pressure generated through this mechanism can be thought of as a source of…

General Relativity and Quantum Cosmology · Physics 2025-01-23 Mrinnoy M. Gohain , Kalyan Bhuyan , Chayanika Chetia

We compute the shadow cast by a charged Morris-Thorne wormhole when the light source is a star located beyond the mouth which is opposite to the observer. First, we provide an extensive analysis of the geodesic properties of the spacetime,…

General Relativity and Quantum Cosmology · Physics 2022-10-26 Mário Raia Neto , Daniela Pérez , Joaquín Pelle

We investigate the gravitational lensing of massless particles around a Kerr-Sen black hole immersed in a magnetized, cold, pressureless plasma medium. Both homogeneous and inhomogeneous plasma distributions are considered in this study to…

General Relativity and Quantum Cosmology · Physics 2026-04-15 Saswati Roy , Shubham Kala , Sayanika Modak , Hemwati Nandan , Amare Abebe

The primary objective of this article is to study the energy condition bounds for spherical and hyperbolic wormholes in well-known $f(R,T)$ theory of gravity. For this purpose, we formulate the field equations for spherically and…

General Relativity and Quantum Cosmology · Physics 2022-08-19 M. Zubair , Quratulien Muneer , Saira Waheed

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

In this work, we study the optical properties of a class of magnetically charged rotating black hole spacetimes. The black holes in question are assumed to be immersed in the quintessence field, and subsequently, the resulting black hole…

General Relativity and Quantum Cosmology · Physics 2022-06-15 Chengxiang Sun , Yunqi Liu , Wei-Liang Qian , Ruihong Yue

Potentiality of the presence of traversable wormholes in the outer/inner regions of the halos of galaxies, situated on the Navarro-Frenk-White (NFW) density profile and Universal Rotation Curve (URC) dark matter models have been…

General Relativity and Quantum Cosmology · Physics 2016-06-10 A. Övgün , M. Halilsoy

We study wormhole geometries embedded in an expanding universe within a four-scalar non-linear $\sigma$ model, where the target-space metric is identified with the spacetime Ricci tensor. In this framework, wormholes can remain stable even…

General Relativity and Quantum Cosmology · Physics 2026-01-16 Taishi Katsuragawa , Shin'ichi Nojiri , Sergei D. Odintsov

In this work, we investigate the shadow properties of the Kerr-Newman-Anti-de Sitter black hole coupled to a nonlinear electrodynamics. We construct the shadow by employing the celestial coordinate approach for observers located at finite…

General Relativity and Quantum Cosmology · Physics 2025-08-20 Mohsen Fathi

This current analysis offers novel wormhole solutions in the background of newly developed extended $f(\mathcal{R},\mathcal{L}_m)$ gravity. We use an anisotropic matter source and a particular type of energy density demonstrating cold dark…

General Relativity and Quantum Cosmology · Physics 2024-03-05 G. Mustafa , Faisal Javed , S. K. Maurya , M. Govender , Amna Saleem
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