scholarly journals Gravitational waves in the extended theory of gravity

2021 ◽  
Author(s):  
Sourav Roy Chowdhury ◽  
Maxim Khlopov
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Degrees Of Freedom ◽  
Standard Theory ◽  
New Approach ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Theory Of Gravity ◽  
New Formula ◽  
Extended Theories

Extended theories of gravity are considered as a new approach for solving the infrared and ultraviolet scale problems; the standard theory of gravity (general relativity) and observational evidence of gravitational waves and subsequent identification of the number of existing polarizations are an effective tool for testing general relativity and extended theories of gravity. The Newman–Penrose method is used to characterize the polarization modes for specific forms of [Formula: see text] in the present study. Both the forms of the [Formula: see text] theory belong to far more general variational class of gravitational waves, capable of presenting up to six separate polarizations states. We have introduced a new [Formula: see text] gravity model as an attempt to have a theory with more parametric regulations so that the model can be used to describe existing issues and discover different directions in gravity physics. The primary goal of this research is to look into the properties of gravitational waves with new cases. The model shows the existence of scalar degrees of freedom in [Formula: see text] gravity metric notation.

scholarly journals Evaporation/Antievaporation and energy conditions in alternative gravity

2018 ◽  
Vol 33 (04) ◽  
pp. 1850030 ◽  
Author(s):  
Andrea Addazi
Keyword(s):  
General Relativity ◽  
Degrees Of Freedom ◽  
Energy Conditions ◽  
Raychaudhuri Equation ◽  
Bonnet Gravity ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories ◽  
Alternative Gravity

We discuss the evaporation and antievaporation instabilities of Nariai solution in extended theories of gravity. These phenomena were explicitly shown in several different extensions of General Relativity, suggesting that a universal cause is behind them. We show that evaporation and antievaporation are originated from deformations of energy conditions on the Nariai horizon. Energy conditions get new contributions from the extra propagating degrees of freedom, which can provide extra focalizing or antifocalizing terms in the Raychaudhuri equation. We show the two explicit cases of [Formula: see text]-gravity and Gauss–Bonnet gravity.

scholarly journals INTERFEROMETRIC DETECTION OF GRAVITATIONAL WAVES: THE DEFINITIVE TEST FOR GENERAL RELATIVITY

2009 ◽  
Vol 18 (14) ◽  
pp. 2275-2282 ◽  
Author(s):  
CHRISTIAN CORDA
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Experimental Tests ◽  
Great Success ◽  
Response Functions ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Interferometric Detection ◽  
Extended Theories ◽  
Einstein’S General Relativity

Even though Einstein's general relativity has achieved great success and passed a lot of experimental tests, it has also shown some shortcomings and flaws which today prompt theorists to ask if it is the definitive theory of gravity. In this essay we show that if advanced projects on the detection of gravitational waves (GWs) improve their sensitivity, allowing us to perform a GW astronomy then accurate angle- and frequency-dependent response functions of interferometers for GWs arising from various theories of gravity, i.e. general relativity and extended theories of gravity, will be the definitive test for general relativity. The papers mentioned in this essay were the world's most-cited in 2007 of the Astroparticle Publication Review of ASPERA with 13 citations.

scholarly journals Charged wormholes in f(R,T)-extended theory of gravity

2019 ◽  
Vol 28 (08) ◽  
pp. 1950098 ◽  
Author(s):  
P. H. R. S. Moraes ◽  
W. de Paula ◽  
R. A. C. Correa
Keyword(s):  
Degrees Of Freedom ◽  
Matter Content ◽  
Nonlinear Electrodynamics ◽  
Energy Conditions ◽  
Field Equations ◽  
Extended Theory ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Theory Of Gravity ◽  
Physical Quantities

Wormholes (WHs) are a solution for General Relativity field equations which characterize a passage or tunnel that connects two different regions of spacetime and is filled by some sort of exotic matter that does not satisfy the energy conditions. On the other hand, it is known that in extended theories of gravity, the extra degrees of freedom once provided may allow the energy conditions to be obeyed and, consequently, the matter content of the WH to be nonexotic. In this work, we obtain, as a novelty in the literature, solutions for charged WHs in the [Formula: see text]-extended theory of gravity. We show that the presence of charge in these objects may be a possibility to respect some stability conditions for their metric. Also, remarkably, the energy conditions are respected in the present approach. In addition, we argue that our framework can be very useful to study the possibility of evolving [Formula: see text] and [Formula: see text]-dimensional WH spacetime within the context of nonlinear electrodynamics, which open a new window to probe the physical quantities in a WH-type solution.

scholarly journals Probing the physical and mathematical structure of f(R)-gravity by PSR J0348 + 0432

2015 ◽  
Vol 12 (04) ◽  
pp. 1550040 ◽  
Author(s):  
Mariafelicia De Laurentis ◽  
Ivan De Martino
Keyword(s):  
General Relativity ◽  
Binary Systems ◽  
Time Derivative ◽  
Mathematical Structure ◽  
Graviton Mass ◽  
Upper Limit ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
First Time ◽  
Extended Theories

There are several approaches to extend General Relativity in order to explain the phenomena related to the Dark Matter and Dark Energy. These theories, generally called Extended Theories of Gravity, can be tested using observations coming from relativistic binary systems as PSR J0348 + 0432. Using a class of analytical f(R)-theories, one can construct the first time derivative of orbital period of the binary systems starting from a quadrupolar gravitational emission. Our aim is to set boundaries on the parameters of the theory in order to understand if they are ruled out, or not, by the observations on PSR J0348 + 0432. Finally, we have computed an upper limit on the graviton mass showing that agree with constraint coming from other observations.

scholarly journals Testing fundamental physics with photon frequency shift

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Luca Buoninfante ◽  
Gaetano Lambiase ◽  
Antonio Stabile
Keyword(s):  
General Relativity ◽  
Excited State ◽  
Frequency Shift ◽  
New Physics ◽  
Electron Spins ◽  
Hydrogen Atoms ◽  
Spin Flip ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories

Abstract We propose a high precision satellite experiment to further test Einstein’s General Relativity and constrain extended theories of gravity. We consider the frequency shift of a photon radially exchanged between two observers located on Earth and on a satellite in circular orbit in the equatorial plane. In General Relativity there exists a peculiar satellite-distance at which the static contribution to the frequency shift vanishes since the effects induced by pure gravity and special relativity compensate, while it can be non-zero in modified gravities, like in models with screening mechanisms. As an experimental device placed on the satellite we choose a system of hydrogen atoms which can exhibit the 1 s spin-flip transition from the singlet (unaligned proton-electron spins) to the triplet (aligned proton-electron spins) state induced by the absorption of photons at 21.1 cm. The observation of an excited state would indicate that the frequency of the emitted and absorbed photon remains unchanged according to General Relativity. On the contrary, a non-zero frequency shift, as predicted in extended theories of gravity, would prevent the spin-flip transition and the hydrogen atoms from jumping into the excited state. Such a detection would signify a smoking-gun signature of new physics beyond special and general relativity.

scholarly journals Reconstructing wormhole solutions in curvature based Extended Theories of Gravity

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Vittorio De Falco ◽  
Emmanuele Battista ◽  
Salvatore Capozziello ◽  
Mariafelicia De Laurentis
Keyword(s):  
General Relativity ◽  
Physical Property ◽  
The Other ◽  
Newtonian Potential ◽  
Spherically Symmetric ◽  
Traversable Wormholes ◽  
Asymptotic Flatness ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories

AbstractStatic and spherically symmetric wormhole solutions can be reconstructed in the framework of curvature based Extended Theories of Gravity. In particular, extensions of the General Relativity, in metric and curvature formalism give rise to modified gravitational potentials, constituted by the classical Newtonian potential and Yukawa-like corrections, whose parameters can be, in turn, gauged by the observations. Such an approach allows to reconstruct the spacetime out of the wormhole throat considering the asymptotic flatness as a physical property for the related gravitational field. Such an argument can be applied for a large class of curvature theories characterising the wormholes through the parameters of the potentials. According to this procedure, possible wormhole solutions could be observationally constrained. On the other hand, stable and traversable wormholes could be a direct probe for this class of Extended Theories of Gravity.

scholarly journals THE PHYSICAL FOUNDATIONS FOR THE GEOMETRIC STRUCTURE OF RELATIVISTIC THEORIES OF GRAVITATION: FROM GENERAL RELATIVITY TO EXTENDED THEORIES OF GRAVITY THROUGH EHLERS–PIRANI–SCHILD APPROACH

2012 ◽  
Vol 09 (08) ◽  
pp. 1250072 ◽  
Author(s):  
S. CAPOZZIELLO ◽  
M. DE LAURENTIS ◽  
L. FATIBENE ◽  
M. FRANCAVIGLIA
Keyword(s):  
General Relativity ◽  
Large Class ◽  
Geometric Structure ◽  
Space Time ◽  
Correct Analysis ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Causal Structures ◽  
Extended Theories ◽  
Theories Of Gravitation

We discuss in a critical way the physical foundations of geometric structure of relativistic theories of gravity by the so-called Ehlers–Pirani–Schild formalism. This approach provides a natural interpretation of the observables showing how relate them to General Relativity and to a large class of Extended Theories of Gravity. In particular we show that, in such a formalism, geodesic and causal structures of space-time can be safely disentangled allowing a correct analysis in view of observations and experiment. As specific case, we take into account the case of f(R)-gravity.

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