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A theory is proposed which allows explaining the observed flat galaxy rotation curves, without needing to invoke dark matter. Whereas other theories have been proposed in the past which realize the same, the present theory rests on basic…

General Physics · Physics 2015-05-13 Rudi Van Nieuwenhove

Globular clusters (GCs) in the Milky Way have characteristic velocity dispersions that are consistent with the predictions of Newtonian gravity, and may be at odds with Modified Newtonian Dynamics (MOND). We discuss a modified gravity (MOG)…

Astrophysics · Physics 2008-06-14 J. W. Moffat , V. T. Toth

NGC1277 is a compact but massive lenticular galaxy that shows no signs of the presence of dark matter. We find that this galaxy's behavior is consistent not only with Newtonian dynamics, but also with the predictions of…

Astrophysics of Galaxies · Physics 2024-02-28 John W. Moffat , Viktor T. Toth

We present $\texttt{MG-evolution}$, an $N$-body code simulating the cosmological structure formation for parametrised modifications of gravity. It is built from the combination of parametrised linear theory with a parametrisation of the…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-03 Farbod Hassani , Lucas Lombriser

Over the last few decades, astronomers and cosmologists have accumulated vast amounts of data clearly demonstrating that our current theories of fundamental particles and of gravity are inadequate to explain the observed discrepancy between…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-22 Constantinos Skordis

One of the main objectives of stage IV galaxy surveys is to constrain gravity on cosmological scales. To this end, it is crucial to make accurate theoretical predictions in the nonlinear regime of structure formation in order to maximise…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-14 Bartolomeo Fiorini

Symmetric teleparallel gravity (STG) is a gravity theory which takes non-metricity tensor to describe gravity effects. In the STG framework, we study the conformal equivalent scalar-tensor theory of f(Q) model and calculate the cosmological…

General Relativity and Quantum Cosmology · Physics 2024-04-26 Dehao Zhao

We explore the cosmological consequences of Modified Gravity (MOG), and find that it provides, using a minimal number of parameters, good fits to data, including CMB temperature anisotropy, galaxy power spectrum, and supernova…

Astrophysics · Physics 2012-01-05 J. W. Moffat , V. T. Toth

The evolution of disk galaxies in modified gravity is studied by using high-resolution N-body simulations. More specifically, we use the weak field limit of two modified gravity theories, i.e., nonlocal gravity (NLG) and…

Astrophysics of Galaxies · Physics 2020-05-28 Neda Ghafourian , Mahmood Roshan , Shahram Abbassi

We present a cosmological realization of Scalar--Tensor--Vector Gravity (STVG--MOG) in which the pre-recombination scalar perturbation dynamics become degenerate with those of $\Lambda$CDM without invoking particle dark matter. In the early…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-29 John W. Moffat

Although the modified dynamics (MOND) proposed by Milgrom successfully accounts for the systematics of galaxy rotation curves and cluster dynamics without invoking dark matter, the idea remains a largely ad hoc modification of Newtonian…

Astrophysics · Physics 2009-10-28 R. H. Sanders

We find a connection between relativistic Modified Newtonian Dynamics (MOND) theories and (scalar) mimetic gravity. We first demonstrate that any relativistic MOND model featuring a unit-timelike vector field, such as TeVeS or…

General Relativity and Quantum Cosmology · Physics 2025-03-17 Guillem Domènech , Alexander Ganz

MOG as a modified gravity theory is designed to be replaced with dark matter. In this theory, in addition to the metric tensor, a massive vector is a gravity field where each particle has a charge proportional to the inertial mass and…

General Relativity and Quantum Cosmology · Physics 2022-06-22 Sohrab Rahvar

The N-body dark matter (DM) simulations point that DM density profiles, e.g. the NFW halo, should be cuspy in its center, but observations disfavour this kind of DM profile. Here we consider whether the observed rotation curves "close" to…

Astrophysics of Galaxies · Physics 2014-11-04 Davi C. Rodrigues , Paulo L. de Oliveira , Julio C. Fabris , Gianfranco Gentile

In this paper, we explore the existence of spherically symmetric strange quark configurations coupled with anisotropic fluid setup in the framework of modified Gauss-Bonnet theory. In this regard, we adopt two models such as \emph{(i)}…

General Relativity and Quantum Cosmology · Physics 2024-11-05 K. Hassan , Tayyab Naseer , M. Sharif

Previous work established a universal form for the equation of motion of small bodies in theories of a metric and other tensor fields that have second-order field equations following from a covariant Lagrangian in four spacetime dimensions.…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Samuel E Gralla

A modified gravity (MOG) theory, that has been successfully fitted to galaxy rotational velocity data, cluster data, the Bullet Cluster 1E0657-56 and cosmological observations, is shown to be in good agreement with the motion of satellite…

Astrophysics · Physics 2008-08-10 J. W. Moffat , V. T. Toth

We study Monge-Amp\`ere gravity (MAG) as an effective theory of cosmological structure formation through optimal transport theory. MAG is based on the Monge-Amp\`ere equation, a nonlinear version of the Poisson equation, that relates the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-13 Bruno Lévy , Yann Brenier , Roya Mohayaee

Scalar fields play an important role in constructing modified gravity theories. In the case of a single scalar field with timelike gradient, the corresponding Lagrangian in the unitary gauge takes the form of spatially covariant gravity…

General Relativity and Quantum Cosmology · Physics 2024-07-23 Yang Yu , Zheng Chen , Xian Gao

A non-singular cosmology is derived in modified gravity (MOG) with a varying gravitational coupling strength $G(t)=G_N\xi(t)$. Assuming that the curvature $k$, the cosmological constant $\Lambda$ and $\rho$ vanish at $t=0$, we obtain a…

General Relativity and Quantum Cosmology · Physics 2007-10-24 J. W. Moffat