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Scalar-tensor theories of gravity that embrace conformal coupling to the scalar curvature are the focal point of cosmology on discussions of inflation and late-time accelerating universe. Although there exists a stringent nucleo-synthesis…

General Relativity and Quantum Cosmology · Physics 2022-04-26 M. Yoshimura

We study the cosmological dynamics of dark energy in a scalar-vector-torsion theory. The vector field is described by the cosmic triad and the scalar field is of the quintessence type with non-minimal coupling to gravity. The coupling to…

General Relativity and Quantum Cosmology · Physics 2023-07-11 Manuel Gonzalez-Espinoza , Giovanni Otalora , Yoelsy Leyva , Joel Saavedra

We present a fully covariant and gauge-invariant analysis of linear cosmological perturbations in Energy-Momentum Squared Gravity. Working within the 1+3 formalism, we derive the exact propagation equations for scalar, vector, and tensor…

General Relativity and Quantum Cosmology · Physics 2025-11-10 Peter K. S. Dunsby , Maria-Alexia Caldis , Eduardo Bittencourt

Modified Gravity (MOG) has been used successfully to explain the rotation curves of galaxies, the motion of galaxy clusters, the Bullet Cluster, and cosmological observations without the use of dark matter or Einstein's cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 J. W. Moffat

Recently, a new class of modified gravity theories formulated via an additional scalar and vector field on top of the standard tensor field has been proposed. The direct implications of these theories are expected to be relevant for…

General Relativity and Quantum Cosmology · Physics 2018-09-11 Phongpichit Channuie , Davood Momeni

We study the global gravitational stability of a gaseous self-gravitating Maclaurin disk in the absence of a halo. Further, we replace Newtonian gravity with the specific Modified gravity theory known as MOG in the relevant literature. MOG…

Astrophysics of Galaxies · Physics 2016-12-14 Mahmood Roshan , Shahram Abbassi , Habib G. Khosroshahi

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

A scalar-tensor theory of gravity is formulated in which $G$ and particle masses are allowed to vary. The theory yields a globally static cosmological model with no evolutionary timescales, no cosmological coincidences, and no flatness and…

General Physics · Physics 2015-10-01 Meir Shimon

We study the global stability of a self-gravitating disk in the context of Modified Gravity (MOG) using N-body simulations. This theory is a relativistic scalar-tensor-vector theory of gravity and presented to address the dark matter…

Astrophysics of Galaxies · Physics 2017-05-17 Neda Ghafourian , Mahmood Roshan

The scalar-vector-tensor theories with second-order equations of motion can accommodate both Horndeski and generalized Proca theories as specific cases. In the presence of a perfect fluid, we study the cosmology in such a most general…

General Relativity and Quantum Cosmology · Physics 2018-11-20 Ryotaro Kase , Shinji Tsujikawa

We consider spatially covariant modified gravity in which the would-be scalar degree of freedom is made non-dynamical and hence there are just two tensorial degrees of freedom, i.e., the same number of dynamical degrees of freedom as in…

General Relativity and Quantum Cosmology · Physics 2021-12-15 Aya Iyonaga , Tsutomu Kobayashi

The Machian cosmological solution satisfying $\phi =O(\rho /\omega)$ in the generalized scalar-tensor theory of gravitation with the varying cosmological constant is summarized. The scalar field $\phi $ with the exponential potential is…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. Miyazaki

We present a comprehensive investigation of cosmological constraints on the class of vector field formulations of modified gravity called Generalized Einstein-Aether models. Using linear perturbation theory we generate cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-25 J. Zuntz , T. G. Zlosnik , F. Bourliot , P. G. Ferreira , G. D. Starkman

The impressive success of the standard cosmological model has suggested to many that its ingredients are all one needs to explain galaxies and their systems. I summarize a number of known problems with this program. They might signal the…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-06 Jacob D. Bekenstein

In this manuscript, we provide a comprehensive study of gravitational lensing by dark compact objects predicted by a Modified Gravity (MOG) based on the Scalar-Vector-Tensor action, and the aim is to analyze new insights into the nature of…

General Relativity and Quantum Cosmology · Physics 2025-03-07 Nagina Rehman , Zoe C. S. Chan , Mubasher Jamil , Mustapha Azreg-Aïnou

Future observations of the large-scale structure have the potential to investigate cosmological models with a high degree of complexity, including the properties of gravity on large scales, the presence of a complicated dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-26 Robert Reischke , Alessio Spurio Mancini , Björn Malte Schäfer , Philipp M. Merkel

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

This paper is dedicated to scrutinizing the cosmology in massive gravity. A matter field of the dark sector is coupled to an effective composite metric while a standard matter field couples to the dynamical metric in the usual way. For this…

General Relativity and Quantum Cosmology · Physics 2016-09-21 Lavinia Heisenberg , Alexandre Refregier

The modified gravity (MOG) theory is applied to the gravitational wave binary merger GW190814 to demonstrate that the modified Tolman-Oppenheimer-Volkoff equation for a neutron star can produce a mass $M=2.6 -2.7 M_\odot$, allowing for the…

General Relativity and Quantum Cosmology · Physics 2020-08-17 J. W. Moffat

A simple model for the dynamics of the Magellanic Stream (MS), in the framework of modified gravity models is investigated. We assume that the galaxy is made up of baryonic matter out of context of dark matter scenario. The model we used…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Hosein Haghi , Sohrab Rahvar