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This paper investigates gravitational lensing effects in the presence of plasma in the strong deflection limit, which corresponds to light rays circling around a compact object and forming higher-order images. While previous studies of this…

General Relativity and Quantum Cosmology · Physics 2025-05-26 Fabiano Feleppa , Valerio Bozza , Oleg Yu. Tsupko

In this paper, we investigated the effect of dark matter on the weak deflection angle by black holes at the galactic center. We consider three known dark matter density profiles such as the Cold Dark Matter (CDM), Scalar Field Dark Matter…

General Relativity and Quantum Cosmology · Physics 2022-05-04 Reggie C. Pantig , Ali Övgün

In this work, we calculate the quantum correction effects on the deflection of light in the spacetime geometry of a quantum improved Kerr black hole pierced by an infinitely long cosmic string. More precisely, we calculate the deflection…

General Relativity and Quantum Cosmology · Physics 2019-07-30 Kimet Jusufi , Ali Övgün

The purpose of this article is twofold. First, we extend the results presented in [Gabriel Crisnejo and Emanuel Gallo, Phys.Rev.D 97, 124016 (2018)] to stationary spacetimes. Specifically, we show that the Gauss-Bonnet theorem can be…

General Relativity and Quantum Cosmology · Physics 2019-11-27 Gabriel Crisnejo , Emanuel Gallo , Kimet Jusufi

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

Weak gravitational lensing by black holes and wormholes in the context of massive gravity (Bebronne and Tinyakov 2009) theory is studied. The particular solution examined is characterized by two integration constants, the mass $M$ and an…

General Relativity and Quantum Cosmology · Physics 2018-05-01 Kimet Jusufi , Nayan Sarkar , Farook Rahaman , Ayan Banerjee , Sudan Hansraj

We calculate the deflection angle of light from a distant source by a galaxy cluster in Weyl's conformal gravity. The general method of calculation is first applied to calculate the deflection angle in Schwarzschild-de Sitter (Kottler)…

General Relativity and Quantum Cosmology · Physics 2019-10-18 Oguzhan Kasikci , Cemsinan Deliduman

Gravitational lensing constitutes one of the most direct observational manifestations of spacetime curvature and provides a powerful probe of compact astrophysical objects. In this work, we present a comprehensive analysis of the bending of…

General Relativity and Quantum Cosmology · Physics 2026-04-21 Partha Pratim Basumallick , Saheb Das , Bhaswati Mandal , Subhadip Sau

We succeed to find compact analytical expressions which allow to easily extract the black hole spin from observations of its shadow, without need to construct or model the entire curve of the shadow. The deformation of Kerr black hole…

General Relativity and Quantum Cosmology · Physics 2017-06-07 O. Yu. Tsupko

Continuing work initiated in an earlier publication [Ishihara, Suzuki, Ono, Kitamura, Asada, Phys. Rev. D {\bf 94}, 084015 (2016) ], we discuss a method of calculating the bending angle of light in a static, spherically symmetric and…

General Relativity and Quantum Cosmology · Physics 2017-02-22 Asahi Ishihara , Yusuke Suzuki , Toshiaki Ono , Hideki Asada

A recent study by Rahaman et al. has shown that the galactic halo possesses the necessary properties for supporting traversable wormholes, based on two observational results, the density profile due to Navarro et al. and the observed flat…

General Relativity and Quantum Cosmology · Physics 2016-04-25 Peter K. F. Kuhfittig

In this paper, we thoroughly explore two crucial aspects of a quantum Schwarzschild black solution within four-dimensional space-time: i) the weak deflection angle, ii) the rigorous greybody factor and, iii) the Dirac quasinormal modes}.…

General Relativity and Quantum Cosmology · Physics 2024-09-18 Ángel Rincón , Ali Övgün , Reggie C. Pantig

In [5] we investigated the response of vacuum energy to a gravitational field by considering a Casimir apparatus in a weak gravitational field. Our approach was based on a conjecture involving the interpretation of spacetime as a refractive…

General Relativity and Quantum Cosmology · Physics 2012-03-01 B. Nazari , M. Nouri-Zonoz

In this work, gravitational lensing in the weak and strong field limits is investigated for black hole spacetime within the framework of Hu-Sawicki $f(R)$ gravity. We employ the Ishihara et al. approach for weak lensing and adopt Bozza's…

General Relativity and Quantum Cosmology · Physics 2025-09-03 Gayatri Mohan , Nashiba Parbin , Umananda Dev Goswami

Analytical series expansions for the bending of light in the equatorial plane of a Kerr black hole are presented in both the strong and weak deflection regimes. It is critical that these are known in analytical form so further analysis can…

General Relativity and Quantum Cosmology · Physics 2009-08-04 Savitri V. Iyer , Edward C. Hansen

In this work, we investigate the signatures of black holes within an effective quantum gravity framework recently proposed in the literature [1] . We begin by outlining the general setup, highlighting the two distinct models under…

General Relativity and Quantum Cosmology · Physics 2025-03-12 N. Heidari , A. A. Araújo Filho , R. C. Pantig , A. Övgün

The existence of quintessential dark energy around a black hole has considerable consequences on its spacetime geometry. Hence, in this article, we explore its effect on horizons and the silhouette generated by a Kerr-Newman black hole in…

General Relativity and Quantum Cosmology · Physics 2020-06-23 Saeed Ullah Khan , Jingli Ren

Weak gravitational lensing provides a unique method to directly measure the distribution of mass in the universe. Because the distortions induced by lensing in the shape of background galaxies are small, the measurement of weak lensing…

Astrophysics · Physics 2009-11-06 Alexandre Refregier , David Bacon

In this paper, we study rotating black holes in symmergent gravity, and use deviations from the Kerr black hole to constrain the parameters of the symmergent gravity. Symmergent gravity induces the gravitational constant $G$ and quadratic…

General Relativity and Quantum Cosmology · Physics 2023-03-28 Reggie C. Pantig , Ali Övgün , Durmuş Demir

This article delves into the observational properties of a Schwarzschild-like black hole (BH). Initially, the research provides a succinct examination of the spacetime geometry and the configuration of its horizon. Furthermore, we study the…

General Relativity and Quantum Cosmology · Physics 2026-03-17 Weiqiang Yang , Mirzabek Alloqulov , Ahmadjon Abdujabbarov , Bobomurat Ahmedov , Chengxun Yuan , Chen Zhou
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