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Explicit tests are presented of the conjectured entropic origin of the gravitational force. The gravitational force on a test particle in the vicinity of the horizon of a large Schwarzschild black hole in arbitrary spacetime dimensions is…

General Relativity and Quantum Cosmology · Physics 2018-08-08 Sourav Bhattacharya , Panagiotis Charalambous , Theodore N Tomaras , Nicolaos Toumbas

We explore a simple spherical model of optically thin accretion on a Schwarzschild black hole, and study the properties of the image as seen by a distant observer. We show that a dark circular region in the center --- a shadow --- is always…

High Energy Astrophysical Phenomena · Physics 2019-12-11 Ramesh Narayan , Michael D. Johnson , Charles F. Gammie

We present new sequences of general relativistic, quasiequilibrium black hole-neutron star binaries. We solve for the gravitational field in the conformal thin-sandwich decomposition of Einstein's field equations, coupled to the equations…

Astrophysics · Physics 2009-11-11 Keisuke Taniguchi , Thomas W. Baumgarte , Joshua A. Faber , Stuart L. Shapiro

In this paper, we explore the behavior of light ray trajectories in the exterior geometry of a rotating black hole within the Rastall theory of gravity, which is surrounded by an inhomogeneous anisotropic electronic cold plasma. By…

General Relativity and Quantum Cosmology · Physics 2024-08-22 Mohsen Fathi , Marco Olivares , José R. Villanueva , Norman Cruz

We give the formulation of the gravitational lensing theory in the strong field limit for a Schwarzschild black hole as a counterpart to the weak field approach. It is possible to expand the full black hole lens equation to work a simple…

General Relativity and Quantum Cosmology · Physics 2015-06-25 V. Bozza , S. Capozziello , G. Iovane , G. Scarpetta

We investigate the properties of the Schwarzschild black hole geometry involving leading one-loop long-distance quantum effects, which arise within the framework of effective field theories of gravity. Our analysis reveals that geodesic…

General Relativity and Quantum Cosmology · Physics 2025-01-29 Zi-Liang Wang , Emmanuele Battista

Applying the quantum field theoretic perturbiner approach to Einstein gravity, we compute the metric of a Schwarzschild black hole order by order in perturbation theory. Using recursion, this calculation can be carried out in de Donder…

High Energy Physics - Theory · Physics 2024-05-31 Poul H. Damgaard , Kanghoon Lee

We discuss spherically symmetric exact solutions of the Einstein equations for quintessential matter surrounding a black hole, which has an additional parameter ($\omega$) due to the quintessential matter, apart from the mass ($M$). In…

General Relativity and Quantum Cosmology · Physics 2016-05-25 Sushant G. Ghosh

A short formula is suggested which approximates photon trajectories in the Schwarzschild field better than other simple prescriptions from the literature. We compare it with various "low-order competitors", namely with those following from…

High Energy Astrophysical Phenomena · Physics 2015-02-13 Oldrich Semerak

In recent works, a framework has been developed to describe (quantum) deformed, spherically symmetric and static black holes in four dimensions. The key idea of this so-called Effective Metric Description (EMD) is to parametrise…

General Relativity and Quantum Cosmology · Physics 2025-08-26 Stefan Hohenegger

We study the gravitational lensing by a Kerr-Sen Black Hole arising in heterotic string theory. A closed form expression for the bending angle of light in equatorial plane of Kerr-Sen Black Hole is derived as a function of impact parameter,…

General Relativity and Quantum Cosmology · Physics 2018-05-24 Rashmi Uniyal , Hemwati Nandan , Philippe Jetzer

We present an extension of work in an earlier paper showing high precision comparisons between black hole perturbation theory and post-Newtonian (PN) theory in their region of overlapping validity for bound, eccentric-orbit, Schwarzschild…

General Relativity and Quantum Cosmology · Physics 2020-07-22 Christopher Munna , Charles R. Evans , Seth Hopper , Erik Forseth

A key obstacle for theory-specific tests of general relativity is the lack of accurate black-hole solutions in beyond-Einstein theories, especially for moderate to high spins. We address this by developing a general framework--based on…

General Relativity and Quantum Cosmology · Physics 2026-01-19 Kelvin Ka-Ho Lam , Adrian Ka-Wai Chung , Nicolás Yunes

It is known how to choose initial data for Einstein's equations describing an arbitrary number of black holes at a moment of time symmetry. This idea has been used to give insight into the cosmological averaging problem. We study the local…

General Relativity and Quantum Cosmology · Physics 2018-07-11 Ingemar Bengtsson , Irina Galstyan

This paper investigates photon motion in black hole of Einstein-Maxwell-dilaton theory, exploring black hole shadows and observational characteristics under various accretion models. We first give the relation of the event horizon, photon…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Junlin Qin , Hong-Er Gong , Yusen Wang , Zhan-Feng Mai , Bofeng Wu , Sen Guo , Enwei Liang

How does the appearance of a strongly lensed system change if a gravitational wave is produced by the lens? In this work we address this question by considering a supermassive black hole binary at the center of the lens emitting…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-29 Leonardo Giani , Cullan Howlett , Tamara M. Davis

An approximate solution to Einstein's equations representing two widely-separated non-rotating black holes in a circular orbit is constructed by matching a post-Newtonian metric to two perturbed Schwarzschild metrics. The spacetime metric…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Kashif Alvi

The strong gravitational lensing of a regular and rotating magnetic black hole in non-minimally coupled Einstein-Yang-Mills theory is studied. We find that, with the increase of any characteristic parameters of this black hole, such as the…

General Relativity and Quantum Cosmology · Physics 2023-10-16 Ruanjing Zhang , Jiliang Jing , Zhipeng Peng , Qihong Huang

Using the Einstein gravitation theory (EGT) we calculate the Schwarzschild metric that is defined in the surrounding vacuum of a spherically symmetric mass distribution, not in rotation. The field equations of the EGT with this metric were…

General Relativity and Quantum Cosmology · Physics 2010-05-25 M. Cattani

We calculate the photon sphere $r_{ph}$ and critical curve $b_c$ for the quantum corrected Schwarzschild black hole, finding that they violate an universal inequalities proved for asymptotically flat black holes which satisfy null energy…

General Relativity and Quantum Cosmology · Physics 2021-09-01 Jun Peng , Minyong Guo , Xing-Hui Feng