scholarly journals Jeans instability in non-minimal matter-curvature coupling gravity

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Cláudio Gomes
Keyword(s):  
Boltzmann Equation ◽  
Dispersion Relation ◽  
Weak Field ◽  
Model Parameters ◽  
Field Limit ◽  
Modified Dispersion Relation ◽  
Weak Field Limit ◽  
Special Cases ◽  
Jeans Instability ◽  
Scalar Potentials

Abstract The weak field limit of the nonminimally coupled Boltzmann equation is studied, and relations between the invariant Bardeen scalar potentials are derived. The Jean’s criterion for instabilities is found through the modified dispersion relation. Special cases are scrutinised and considerations on the model parameters are discussed for Bok globules.

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 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.

Weak-field limit

2010 ◽  
pp. 165-208
Author(s):  
Salvatore Capozziello ◽  
Valerio Faraoni
Keyword(s):  
Weak Field ◽  
Field Limit ◽  
Weak Field Limit

scholarly journals Weak field limit of higher dimensional massive Brans-Dicke gravity: Observational constraints

2020 ◽  
Vol 101 (2) ◽  
Author(s):  
Özgür Akarsu ◽  
Alexey Chopovsky ◽  
Valerii Shulga ◽  
Ezgi Yalçınkaya ◽  
Alexander Zhuk
Keyword(s):  
Weak Field ◽  
Observational Constraints ◽  
Field Limit ◽  
Weak Field Limit ◽  
Higher Dimensional

scholarly journals GRAVITATIONAL LENSING IN THE WEAK FIELD LIMIT BY A BRANEWORLD BLACK HOLE

2005 ◽  
Vol 20 (32) ◽  
pp. 2487-2496 ◽  
Author(s):  
A. S. MAJUMDAR ◽  
NUPUR MUKHERJEE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Lensing ◽  
Cosmic Ray ◽  
Weak Field ◽  
High Energy ◽  
High Energy Particle ◽  
Field Limit ◽  
Weak Field Limit ◽  
Point Light

The existence of braneworld black holes may be of primordial origin, or may even be produced in high energy particle collisions in the laboratory and in cosmic ray showers as well. These black holes obey a modified mass–radius relationship compared to standard Schwarzschild black holes. Using the variational principle we calculate the bending angle of a light ray near the horizon of a braneworld black hole in the weak field limit. We next derive the expressions of several lensing quantities like the Einstein radius and the magnification for a point light source. These expressions are modified compared to the lensing quantities for standard Schwarzschild black holes and contain the scale of the extra dimensions.

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