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The static vacuum spherically symmetric solutions in massive gravity are obtained both analytically and numerically. The solutions depend on two parameters (integration constants): the mass M (or, equivalently, the Schwarzschild radius),…

General Relativity and Quantum Cosmology · Physics 2011-06-10 Michael V. Bebronne , Peter G. Tinyakov

We apply a general relativistic framework to static and rotating black hole solutions in Scalar-Tensor-Vector Gravity or modified gravity (MOG). Our results yield exact analytic, closed-form relations expressing the mass $M$, the MOG…

General Relativity and Quantum Cosmology · Physics 2026-04-10 José Miguel Rojas , Mehrab Momennia

The shadows cast by non-rotating and rotating modified gravity (MOG) black holes are determined by the two parameters mass $M$ and angular momentum $J=Ma$. The sizes of the shadows cast by the spherically symmetric static Schwarzschild-MOG…

General Relativity and Quantum Cosmology · Physics 2015-03-26 J. W. Moffat

We formulate the junction conditions for Scalar-Tensor-Vector Gravity (STVG/MOG), proposed by J.~W.~Moffat. Using these conditions, the theory of gravitational collapse is constructed. In the collapsing process, an interior…

General Relativity and Quantum Cosmology · Physics 2026-05-19 Debanjan Debnath , Anant Badal , Kaushik Bhattacharya

We consider the C-metric as a gravitational field configuration that describes an accelerating black hole in the presence of a semi-infinite cosmic string, along the accelerating direction. We adopt the expression for the gravitational…

General Relativity and Quantum Cosmology · Physics 2022-11-30 F. L. Carneiro , S. C. Ulhoa , J. W. Maluf

We have studied influence of STVG in circular motion of massive particle around the Schwarzschild-MOG black hole and discussed the Innermost Stable Circular Orbit (ISCO) and Marginally Bound Orbit (MBO) position of massive test particle.…

General Relativity and Quantum Cosmology · Physics 2023-11-07 B. Turimov , A. Nosirov , A. Abdujabbarov

The paper has explored analogue of gravitational synchrotron massive particle and Penrose process in MOdified Gravity (MOG) known as Scalar-Tensor-Vector-Gravity (STVG). Investigation of the gravitational field around Kerr-MOG black hole…

General Relativity and Quantum Cosmology · Physics 2023-06-30 Bobur Turimov , Husan Alibekov , Pulat Tadjimuratov , Ahmadjon Abdujabbarov

The existence of black holes is a central prediction of general relativity and thus serves as a basic consistency test for modified theories of gravity. In spherical symmetry, only two classes of dynamic solutions are compatible with the…

General Relativity and Quantum Cosmology · Physics 2022-03-01 Sebastian Murk

We present calculations for the anticipated shadow sizes of Sgr A* and the supermassive black hole in the galaxy M87 in the context of the MOG modified theory of gravity (also known as Scalar-Tensor-Vector-Gravity, or STVG). We demonstrate…

General Relativity and Quantum Cosmology · Physics 2020-01-23 J. W. Moffat , V. T. Toth

One of the most important issues in relativistic astrophysics is to explain the origin mechanisms of (ultra)high energy charged particle components of cosmic rays. Black holes (BHs) being huge reservoirs of (gravitational) energy can be…

General Relativity and Quantum Cosmology · Physics 2024-04-17 Saeed Ullah Khan , Javlon Rayimbaev , Zdenek Stuchlík

In this paper, we consider the problems of spherical gravitational collapse and accretion using a spherically symmetric, spatially homothetic spacetime, that is, as an exact solution (cqg1) of the field equations of general relativity.…

Astrophysics · Physics 2007-05-23 Sanjay M Wagh

The Quasinormal modes (QNMs) for gravitational and electromagnetic perturbations are calculated in a Scalar-Tensor-Vector (Modified Gravity) spacetime, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters…

General Relativity and Quantum Cosmology · Physics 2018-04-18 Luciano Manfredi , Jonas Mureika , John Moffat

Here we apply the Generalized Second Law of Thermodynamics (GSL) to black holes accreting and emitting in the present Universe and derive upper limits on the variation in the gravitational constant G. The limits depend on how the…

Astrophysics · Physics 2007-06-21 Jane H MacGibbon

We pioneer the black hole mass gap as a powerful new tool for constraining modified gravity theories. These theories predict fifth forces that alter the structure and evolution of population-III stars, exacerbating the pair-instability.…

General Relativity and Quantum Cosmology · Physics 2020-12-16 Maria C. Straight , Jeremy Sakstein , Eric J. Baxter

The exact time-dependent solution is obtained for a magnetic field growth during a spherically symmetric accretion into a black hole (BH) with a Schwarzschild metric. Magnetic field is increasing with time, changing from the initially…

High Energy Astrophysical Phenomena · Physics 2019-06-03 G. S. Bisnovatyi-Kogan

We obtain the solution of a generalized ABG STVG black hole with the nonlinear tensor field $B_{\mu \nu }$ in the scalar-tensor-vector gravity. This black hole is endowed with four parameters, the black hole mass $M$, the parameter $\alpha$…

General Relativity and Quantum Cosmology · Physics 2020-11-04 Xin-Chang Cai , Yan-Gang Miao

We examine the accretion process onto the black hole with a string cloud background, where the horizon of the black hole has an enlarged radius $r_H=2 M/(1-\alpha)$, due to the string cloud parameter $\alpha\; (0 \leq \alpha < 1)$. The…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Apratim Ganguly , Sushant G. Ghosh , Sunil D. Maharaj

We study a minimal extension of a recently proposed modification of general relativity that draws on concepts from topological field theory to resolve aspects of the cosmological constant problem. In the original model, the field content of…

General Relativity and Quantum Cosmology · Physics 2022-02-16 Stephon Alexander , Steven J. Clark , Gabriel Herczeg , Michael W. Toomey

We examine the steady-state spherically symmetric accretion of relativistic fluids, with a polytropic equation of state, onto a higher dimensional Schwarzschild black hole. The mass accretion rate, critical radius, and flow parameters are…

General Relativity and Quantum Cosmology · Physics 2013-11-14 Anslyn J. John , Sushant G. Ghosh , Sunil D. Maharaj

Scalar Tensor Vector Gravity(STVG) is a fully covariant Lorentz invariant alternative theory of gravity also called as MOdified Gravity(MOG) which modifies General Relativity(GR) with dynamical massive vector field and scalar fields. In…

General Relativity and Quantum Cosmology · Physics 2022-04-13 Sreekanth Harikumar , Marek Biesiada