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The behavior of a scalar field theory near the event horizon in a rotating black hole background can be effectively described by a two dimensional field theory in a gauge field background. Based on this fact, we proposal that the quantum…

High Energy Physics - Theory · Physics 2012-05-21 Tao Zhu

The magnetorotational instability(MRI) in the Kerr spacetime is studied on a 3+1 viewpoint. The Maxwell's equations are expressed in a circularly orbiting observer's frame that co-rotates with matter in Keplerian orbits. There exist large…

Astrophysics · Physics 2009-11-10 M. Yokosawa , T. Inui

Modified gravity theories such as Modified Newtonian Dynamics (MOND) and Scalar-Tensor-Vector Gravity (STVG) have been proposed as alternatives to dark matter, but decisive tests have been hindered by degeneracies between baryonic structure…

Astrophysics of Galaxies · Physics 2026-05-12 Zheng-long Wang , Yue-Lin Sming Tsai , Lan Zhang , Yin Wu , Haining Li , Xiang-Xiang Xue , Hongsheng Zhao , Yi-Zhong Fan

Recently, a relativistic gravitation theory has been proposed [J. D. Bekenstein, Phys. Rev. D {\bf 70}, 083509 (2004)] that gives the Modified Newtonian Dynamics (or MOND) in the weak acceleration regime. The theory is based on three…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Dimitrios Giannios

Polarization holonomy is analytically determined for a class of closed, spherical trajectories of light transiting a black hole in the Kerr metric. The leading order geometric optics approximation admits a closed-form expression of such…

General Relativity and Quantum Cosmology · Physics 2024-11-12 Mark T. Lusk

Deviations from the standard $\Lambda$CDM model motivate an interpretation of early universe cosmology using the Scalar-Tensor-Vector-Gravity (STVG) theory. A constraint analysis carried out by Valentino, Melchiorri and Silk, revealed…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-27 J. W. Moffat

We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and use the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is…

High Energy Physics - Theory · Physics 2011-02-03 Valeri P. Frolov , Pavel Krtous

Thermal emission from the accretion disc around a black hole can be polarized, due to Thomson scattering in a disc atmosphere. In Newtonian space, the polarization angle must be either parallel or perpendicular to the projection of the disc…

Astrophysics · Physics 2008-12-04 M. Dovciak , F. Muleri , R. W. Goosmann , V. Karas , G. Matt

The discovery of frame-dragging effects in binary pulsar timing experiments requires a compact companion with sufficiently large spin. A pulsar orbiting a fast rotating black hole could provide an appropriate test system. In this paper we…

Astrophysics · Physics 2007-05-23 N. Wex

The radio source Sgr A* in the Galactic center emits a polarized spectrum at millimeter and sub-millimeter wavelengths that is strongly suggestive of relativistic disk accretion onto a massive black hole. We use the well-constrained mass of…

Astrophysics · Physics 2009-11-06 Benjamin C. Bromley , Fulvio Melia , Siming Liu

A key challenge in imaging supermassive black holes is disentangling gravitational effects from plasma physics in order to accurately determine spacetime properties, particularly black hole spin. In this Letter, we present a fully covariant…

General Relativity and Quantum Cosmology · Physics 2025-08-11 Yehui Hou , Jiewei Huang , Minyong Guo , Yosuke Mizuno , Bin Chen

We investigate the shadow cast by a regular black hole in scalar-tensor-vector mOdified gravity theory. This black hole differs from a Schwarzschild-Kerr black hole by the dimensionless parameter $\beta$. The size of the shadow depends on…

General Relativity and Quantum Cosmology · Physics 2024-09-09 Subhadip Sau , John W. Moffat

The rotating loop quantum gravity black hole is a newly proposed non-singular black hole, which eliminates spacetime singularities when a regularization parameter is introduced through loop quantum corrections. This parameter is expected to…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Zhong-Wu Xia , Hao Yang , Yan-Gang Miao

The imminent detection of gravitational waves will trigger precision tests of gravity through observations of quasinormal ringing of black holes. While General Relativity predicts just two polarizations of gravitational waves, the so-called…

General Relativity and Quantum Cosmology · Physics 2011-02-02 Paul D. Lasky , Daniela D. Doneva

The stability of the magnetically charged Reissner-Nordstrom black hole solution is investigated in the context of a theory with massive charged vector mesons. By exploiting the spherical symmetry of the problem, the linear perturbations…

High Energy Physics - Theory · Physics 2010-11-01 S. Alexander Ridgway , Erick J. Weinberg

We study the dynamical and thermodynamic evolution of a Schwarzschild black hole in Modified Gravity (MOG) under a scalar gravitational wave breathing mode. The time-dependent apparent horizon reveals that both the scalar strain velocity…

General Relativity and Quantum Cosmology · Physics 2026-04-07 Nikko John Leo S. Lobos , Emmanuel T. Rodulfo

We study stationary slowly rotating black holes, up to quadratic order in the spin angular momentum, in dynamical Chern-Simons gravity and shift symmetric Einstein scalar Gauss-Bonnet gravity, as models of string-inspired gravities. These…

General Relativity and Quantum Cosmology · Physics 2020-10-14 Keisuke Nakashi , Masashi Kimura

The tachyonic instability of the Kerr black holes is analyzed in the Einstein-scalar theory with the quadratic scalar couplings to two topological terms which are parity-even Gauss-Bonnet and parity-odd Chern-Simons terms. For positive…

General Relativity and Quantum Cosmology · Physics 2021-07-28 De-Cheng Zou , Yun Soo Myung

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

We model the scalar waves produced during the ringdown stage of binary black hole coalescence in Einstein scalar Gauss-Bonnet (EsGB) gravity, using numerical relativity simulations of the theory in the decoupling limit. Through a conformal…

General Relativity and Quantum Cosmology · Physics 2023-06-14 Tamara Evstafyeva , Michalis Agathos , Justin L. Ripley