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The field equations for Scalar-Tensor-Vector-Gravity (STVG) or modified gravity (MOG) have a static, spherically symmetric black hole solution determined by the mass $M$ with two horizons. The strength of the gravitational constant is…

General Relativity and Quantum Cosmology · Physics 2015-05-05 J. W. Moffat

The scalar-tensor-vector gravity (STVG) theory has attracted significant interest due to its ability to effectively address the issue of galaxy rotation curves and clusters of galaxies without considering the influence of dark matter. In…

General Relativity and Quantum Cosmology · Physics 2024-09-04 Wentao Liu , Di Wu , Xiongjun Fang , Jiliang Jing , Jieci Wang

A covariant modified gravity (MOG) is formulated by adding to general relativity two new degrees of freedom, a scalar field gravitational coupling strength $G= 1/\chi$ and a gravitational spin 1 vector field $\phi_\mu$. The $G$ is written…

General Relativity and Quantum Cosmology · Physics 2021-02-17 J. W. Moffat

The astrophysical consequences of the presence of a quintessence scalar field on the evolution of the horizon and on the accretion disk surrounding a static black hole, in the Scalar-Vector-Tensor version of Modified Gravity (MOG), are…

General Relativity and Quantum Cosmology · Physics 2023-09-15 Haidar Sheikhahmadi , Saheb Soroushfar , S. N. Sajadi , Tiberiu Harko

We consider the case of rotating black holes in a dark-matter-emulating theory of gravity called MOG. The latter introduces a gravitational vector field with an associated gravitational charge proportional to the black hole mass and a…

General Relativity and Quantum Cosmology · Physics 2018-12-14 Michael F. Wondrak , Piero Nicolini , John W. Moffat

In this paper we have examined spherical accretion onto Schwarzschild MOG Black Holes within the framework of Modified Gravity. Using isothermal test fluids, we analyze the behavior of the flow near the critical (sonic) point for various…

General Relativity and Quantum Cosmology · Physics 2025-10-31 Ayyesha K. Ahmed , M Z A Moughal

In this paper we study the accretion of matter onto the black holes and the shadow images obtained by an infalling accretion flow of gas in a theory of massive gravity (MG) with a spontaneously breaking Lorentz symmetry. This black hole…

General Relativity and Quantum Cosmology · Physics 2021-10-20 Abdul Jawad , Kimet Jusufi , M. Umair Shahzad

The polarized images of a synchrotron emitting ring are studied in the spacetime of a rotating black hole in the Scalar-Tensor-Vector-Gravity (STVG) theory. The black hole owns an additional dimensionless MOG parameter described its…

General Relativity and Quantum Cosmology · Physics 2022-10-26 Xin Qin , Songbai Chen , Zelin Zhang , Jiliang Jing

In this paper, we present a black hole solution with a cosmological constant in the Scalar-Tensor-Vector Modified Gravity (MOG) theory, where the strength of the gravitational constant is determined by $G = G_\text{N}(1+\alpha)$. We derive…

General Relativity and Quantum Cosmology · Physics 2024-02-22 Wentao Liu , Xiongjun Fang , Jiliang Jing , Jieci Wang

Scalar-tensor-vector gravity, also known as modified gravity (MOG), has emerged as an alternative to General Relativity (GR). It aims to explain astrophysical phenomena without invoking dark matter. The S-stars orbiting the supermassive…

General Relativity and Quantum Cosmology · Physics 2026-05-21 Ioannis Liodis , Gernot Heissel , Rita Mastroioanni , Jai Grover , Dario Izzo

Scalar Tensor Vector Gravity (STVG) is an alternative theory of gravitation that has successfully explained the rotation curves of nearby galaxies, the dynamics of galactic clusters, and cosmological data without dark matter, but has hardly…

High Energy Astrophysical Phenomena · Physics 2017-06-28 Daniela Pérez , Federico G. Lopez Armengol , Gustavo E. Romero

In astrophysics, the process of a massive body acquiring matter is referred to as accretion. The extraction of gravitational energy occurs as a result of the infall. Since it converts gravitational energy into radiation, accretion onto dark…

General Relativity and Quantum Cosmology · Physics 2023-06-01 Kourosh Nozari , Sara Saghafi , Fateme Aliyan

We explore charged black holes in Scalar-Tensor-Vector Gravity (STVG), unveiling their distinctive features across multiple physical domains. Our topological analysis reveals that the STVG coupling parameter $\alpha$ bolsters thermal…

General Relativity and Quantum Cosmology · Physics 2025-11-07 Erdem Sucu , Kuantay Boshkayev , Yassine Sekhmani , İzzet Sakallı , Mohsen Fathi

We consider the cosmological consequences of a special scalar-tensor-vector theory of gravity, known as MOG (for MOdified Gravity), proposed to address the dark matter problem. This theory introduces two scalar fields $G(x)$ and $\mu(x)$,…

General Relativity and Quantum Cosmology · Physics 2018-02-14 Sara Jamali , Mahmood Roshan , Luca Amendola

We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and…

General Relativity and Quantum Cosmology · Physics 2016-05-20 Jonas R. Mureika , John W. Moffat , Mir Faizal

In the work, we have presented detailed analyses of the event horizon and curvature properties of spacetime around a regular black hole in modified gravity so-called regular MOG black hole. The motion of neutral, electrically charged and…

General Relativity and Quantum Cosmology · Physics 2020-10-27 Javlon Rayimbaev , Pulat Tadjimuratov , Ahmadjon Abdujabbarov , Bobomurat Ahmedov , Malika Khudoyberdieva

A regular rotating MOG (modified gravity) compact object is derived that reduces to the Kerr black hole when the parameter $\alpha=0$. Physical consequences of the dark compact object, which is regular everywhere in spacetime for $\alpha >…

General Relativity and Quantum Cosmology · Physics 2021-02-15 J. W. Moffat

In astrophysics, accretion is the process by which a massive object acquires matter. The infall leads to the extraction of gravitational energy. Accretion onto dark compact objects such as black holes, neutron stars, and white dwarfs is a…

General Relativity and Quantum Cosmology · Physics 2024-12-19 Kourosh Nozari , Sara Saghafi , Mohammad Hassani

The accretion of test fluids flowing onto a black hole is investigated. Particularly, by adopting a dynamical Hamiltonian approach, we are capable to find the critical points for various cases of black hole in conformal gravity. In these…

General Relativity and Quantum Cosmology · Physics 2021-02-03 G. Abbas , A. Ditta

Scalar Tensor Vector Gravity(STVG) is one of modified gravity theories developed by John Moffat(2005). MOG is abbreviated name for this theory.It can explain a galactic rotation curve and the structure formation without dark matter. It can…

Astrophysics of Galaxies · Physics 2012-02-21 Takayuki Suzuki
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