scholarly journals A GENERAL SOLUTION IN THE NEWTONIAN LIMIT OF f(R)-GRAVITY

2009 ◽  
Vol 24 (09) ◽  
pp. 659-665 ◽  
Author(s):  
S. CAPOZZIELLO ◽  
A. STABILE ◽  
A. TROISI
Keyword(s):  
General Solution ◽  
Gravity Model ◽  
General Result ◽  
Weak Field ◽  
Newtonian Limit ◽  
Newtonian Potential ◽  
Field Limit ◽  
Weak Field Limit ◽  
Theories Of Gravity ◽  
Physical Consequences

We show that any analytic f(R)-gravity model, in the metric approach, presents a weak field limit where the standard Newtonian potential is corrected by a Yukawa-like term. This general result has never been pointed out but often derived for some particular theories. This means that only f(R) = R allows to recover the standard Newton potential while this is not the case for other relativistic theories of gravity. Some considerations on the physical consequences of such a general solution are addressed.

scholarly journals Newtonian, Post-Newtonian and Parametrized Post-Newtonian limits of f(R, 𝒢) gravity

2014 ◽  
Vol 11 (10) ◽  
pp. 1450082 ◽  
Author(s):  
Mariafelicia De Laurentis ◽  
Antonio Jesus Lopez-Revelles
Keyword(s):  
General Solution ◽  
Analytic Functions ◽  
Green's Functions ◽  
Green’S Functions ◽  
Weak Field ◽  
Ricci Scalar ◽  
Newtonian Limit ◽  
Field Limit ◽  
Weak Field Limit ◽  
Special Cases

We discuss in detail the weak field limit of f(R, 𝒢) gravity taking into account analytic functions of the Ricci scalar R and the Gauss–Bonnet invariant 𝒢. Specifically, we develop, in metric formalism, the Newtonian, Post-Newtonian (PN) and Parametrized Post-Newtonian (PPN) limits starting from general f(R, 𝒢) Lagrangian. The special cases of f(R) and f(𝒢) gravities are considered. In the case of the Newtonian limit of f(R, 𝒢) gravity, a general solution in terms of Green's functions is achieved.

GALACTIC AND ASTROPHYSICAL SIZES FROM SCALAR-TENSOR THEORY OF GRAVITY

2004 ◽  
Vol 13 (02) ◽  
pp. 359-371 ◽  
Author(s):  
GIUSEPPE BASINI ◽  
MARCO RICCI ◽  
FULVIO BONGIORNO ◽  
SALVATORE CAPOZZIELLO
Keyword(s):  
Scalar Field ◽  
Spiral Galaxies ◽  
Weak Field ◽  
Newtonian Potential ◽  
Scalar Tensor Theory ◽  
Field Limit ◽  
Weak Field Limit ◽  
Tensor Theory ◽  
Flat Rotation Curves ◽  
Theory Of Gravity

We investigate the weak-field limit of scalar-tensor theory of gravity and show that results are directly depending on the coupling and self-interaction potential of the scalar field. In particular, corrections are derived for the Newtonian potential. We discuss astrophysical applications of the results, in particular the flat rotation curves of spiral galaxies.

scholarly journals The post-Newtonian limit of hybrid f(R)-gravity

2018 ◽  
Vol 191 ◽  
pp. 07009 ◽  
Author(s):  
Polina Dyadina ◽  
Sofya Labazova
Keyword(s):  
Solar System ◽  
Weak Field ◽  
Newtonian Limit ◽  
Field Limit ◽  
Weak Field Limit

The post-Newtonian formalism is developed for hybrid f(R)-gravity. The model is tested in the weak field regime of the Solar System. Using scalartensor representation of hybrid f(R)-gravity we impose restrictions on the parameters of the theory and show that hybrid f(R)-gravity is not ruled out by the observations in the weak field limit.

scholarly journals Gravitoelectromagnetism, Solar System Tests, and Weak-Field Solutions in f (T,B) Gravity with Observational Constraints

Universe ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 34 ◽  
Author(s):  
Gabriel Farrugia ◽  
Jackson Levi Said ◽  
Andrew Finch
Keyword(s):  
Solar System ◽  
Teleparallel Gravity ◽  
Weak Field ◽  
Observational Constraints ◽  
Field Limit ◽  
Potential Models ◽  
Weak Field Limit ◽  
Rotating Systems ◽  
Theories Of Gravity ◽  
Analogous Effect

Gravitomagnetism characterizes phenomena in the weak-field limit within the context of rotating systems. These are mainly manifested in the geodetic and Lense-Thirring effects. The geodetic effect describes the precession of the spin of a gyroscope in orbit about a massive static central object, while the Lense-Thirring effect expresses the analogous effect for the precession of the orbit about a rotating source. In this work, we explore these effects in the framework of Teleparallel Gravity and investigate how these effects may impact recent and future missions. We find that teleparallel theories of gravity may have an important impact on these effects which may constrain potential models within these theories.

scholarly journals An f(R) Gravitation for Galactic Environments

2006 ◽  
Vol 2 (S235) ◽  
pp. 138-138
Author(s):  
Y. Sobouti
Keyword(s):  
Central Body ◽  
Weak Field ◽  
Constant Speed ◽  
Newtonian Potential ◽  
Logarithmic Correction ◽  
Field Limit ◽  
Schwarzschild Metric ◽  
Weak Field Limit ◽  
Fourth Root ◽  
Fisher Relation

We propose [Sobouti, arXiv:astro-ph/0603302] an f(R) modification of GR, which admits of a modified Schwarzschild metric. In the weak field limit this amounts to adding a small logarithmic correction to the newtonian potential. A test star moving in such a spacetime acquires a constant speed at large distances. From observations of the velocity curves of spirals, this speed turns out to be proportional to the fourth root of the mass of the central body, in compliance with the Tully-Fisher relation. A variance of MOND emerges as a consequence of the formalism.

scholarly journals Giant low-surface-brightness dwarf galaxy as a test bench for MOdified Gravity

2020 ◽  
Vol 493 (2) ◽  
pp. 2373-2376 ◽  
Author(s):  
Ivan de Martino
Keyword(s):  
Dark Matter ◽  
Modified Gravity ◽  
Dwarf Galaxy ◽  
Weak Field ◽  
Newtonian Potential ◽  
Modified Theories Of Gravity ◽  
Weak Field Limit ◽  
Low Surface Brightness ◽  
Standard Cosmological Model ◽  
Theories Of Gravity

ABSTRACT The lack of detection of supersymmetric particles is leading to look at alternative avenues for explaining dark matter’s effects. Among them, modified theories of gravity may play an important role accounting even for both dark components needed in the standard cosmological model. Scalar–tensor–vector gravity theory has been proposed to resolve the dark matter puzzle. Such a modified gravity model introduces, in its weak field limit, a Yukawa-like correction to the Newtonian potential, and is capable to explain most of the phenomenology related to dark matter at scale of galaxies and galaxy clusters. Nevertheless, some inconsistencies appear when studying systems that are supposed to be dark matter dominated such as dwarf galaxies. In this sense, Antlia II, an extremely diffuse galaxy which has been recently discovered in Gaia’s second data release, may serve to probe the aforementioned theory against the need for invoking dark matter. Our analysis shows several inconsistencies and leads to argue that MOdified Gravity may not be able to shed light on the intriguing nature of dark matter.

An f(R) gravitation for galactic environments

2006 ◽  
Vol 2 (S238) ◽  
pp. 451-452
Author(s):  
Yousef Sobouti
Keyword(s):  
Central Body ◽  
Weak Field ◽  
Newtonian Potential ◽  
Logarithmic Correction ◽  
Field Limit ◽  
Weak Field Limit ◽  
Asymptotic Speed ◽  
Fourth Root ◽  
Fisher Relation

AbstractWe propose an action-based f(R) modification of Einstein's gravity which admits of a modified Schwarzschild-deSitter metric. In the weak field limit this amounts to adding a small logarithmic correction to the Newtonian potential. A test star moving in such a spacetime acquires a constant asymptotic speed at large distances. This speed turns out to be proportional to the fourth root of the mass of the central body in compliance with the Tully-Fisher relation. A variance of MOND's gravity emerges as an inevitable consequence of the proposed formalism.

scholarly journals NEWTONIAN LIMIT OF STRING-DILATON GRAVITY

2003 ◽  
Vol 12 (05) ◽  
pp. 843-852 ◽  
Author(s):  
S. CAPOZZIELLO ◽  
G. LAMBIASE
Keyword(s):  
Scalar Field ◽  
Spiral Galaxies ◽  
Weak Field ◽  
The Self ◽  
Newtonian Potential ◽  
Nonminimal Coupling ◽  
Dilaton Gravity ◽  
Field Limit ◽  
Weak Field Limit ◽  
Flat Rotation Curves

We study the weak-field limit of string-dilaton gravity and derive corrections to the Newtonian potential having strength directly depends on the self interaction potential and the nonminimal coupling of the dilaton scalar field. We discuss also possible astrophysical applications of the results, in particular the flat rotation curves of spiral galaxies.

scholarly journals Quantum Faraday Effect in the Universe

2017 ◽  
Vol 45 ◽  
pp. 1760046
Author(s):  
Lídice Cruz Rodríguez ◽  
Aurora Pérez Martínez ◽  
Gabriella Piccinelli ◽  
Elizabeth Rodríguez Querts
Keyword(s):  
Faraday Effect ◽  
Weak Field ◽  
Field Limit ◽  
Self Energy ◽  
Weak Field Limit ◽  
Resonant Behavior ◽  
Degenerate Regime ◽  
The Universe ◽  
Resonant Mechanism ◽  
Recombination Epoch

We study the Quantum Faraday rotation starting from the photon self-energy in the presence of a constant magnetic field. The Faraday angle is calculated in the non-degenerate regime and for weak field limit. Two physical scenarios, possibly characterized by these conditions, are the recombination epoch and the jets originated in pulsars. We discuss the resonant behavior that the Faraday angle exhibits in these scenarios and investigate the possibility of detecting cosmic magnetic fields through this resonant mechanism.

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