scholarly journals Gravitational Waves in Scalar–Tensor–Vector Gravity Theory

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 9
Author(s):  
Yunqi Liu ◽  
Wei-Liang Qian ◽  
Yungui Gong ◽  
Bin Wang
Keyword(s):  
Field Equation ◽  
Vector Field ◽  
Gravitational Waves ◽  
Relative Motion ◽  
Modified Gravity ◽  
Gravity Theory ◽  
Test Particles ◽  
Stress Energy ◽  
Self Gravity ◽  
Perturbed Equation

In this paper, we study the properties of gravitational waves in the scalar–tensor–vector gravity theory. The polarizations of the gravitational waves are investigated by analyzing the relative motion of the test particles. It is found that the interaction between the matter and vector field in the theory leads to two additional transverse polarization modes. By making use of the polarization content, the stress-energy pseudo-tensor is calculated by employing the perturbed equation method. Additionally, the relaxed field equation for the modified gravity in question is derived by using the Landau–Lifshitz formalism suitable to systems with non-negligible self-gravity.

Motion of test particles for Weyl-interaction modified gravity

2019 ◽  
Vol 28 (16) ◽  
pp. 2040014
Author(s):  
Hyung Won Lee ◽  
Asghar Qadir
Keyword(s):  
Dark Matter ◽  
Quantum Gravity ◽  
Modified Gravity ◽  
Weyl Tensor ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Satisfactory Explanation ◽  
Test Particles ◽  
Stress Energy ◽  
Hilbert Action

Since LHC has still given no signal of Supersymmetry, though the energy at which the signal was expected has been passed, one is left short of any good candidate for dark matter. We had proposed [A. Qadir, H. W. Lee and K. Y. Kim, Int. J. Mod. Phys. D 26 (2017) 1741001, 10 pp.] a modification of the Einstein–Hilbert action to explicitly display a term of matter and gravity interaction, [Formula: see text]. The hope had been that this would also resolve the problem of Quantum Gravity. However, the argument given for the purpose of quantum gravity, would more naturally lead one to expect the contraction, [Formula: see text], of the Weyl tensor with two copies of the stress–energy tensor rather than the product of the Ricci scalar and the trace of the stress–energy tensor. Here, the attempt is made to see if this prescription will provide a satisfactory explanation of the dark matter at all scales. One would then try to see if the problem of quantum gravity is resolved by the same prescription.

scholarly journals Persamaan Gelombang Gravitasi untuk Teori Proca yang Digeneralisasi

2020 ◽  
Vol 5 ◽  
Author(s):  
Marliana Marliana ◽  
Agustina Widiyani ◽  
Azwar Sutiono ◽  
Agus Suroso ◽  
Freddy P. Zen
Keyword(s):  
Black Holes ◽  
Vector Field ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
General Equation ◽  
Direct Detection ◽  
Gravity Theory ◽  
Binary Black Holes ◽  
Massive Vector

<p class="AbstractEnglish"><strong>Abstract:</strong> The direct detection of gravitational waves from binary black holes and neutron stars have been taking a new oportunities to test teori of gravity.The gravitational wave is affected by the modification of a gravity theory during propagation at cosmological distances. By comparing general equation of gravtiational wave and modification of gravity theory, is obtained equation of gravitational wave for the generalized Proca theories. As a result, we find equation of gravitational wave for the generalized Proca theory. We conclude that the massive vector field affected propagation of gravitational wave.  we can use the result to test the generalized Proca theory.    </p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> Dengan terdeteksinya gelombang gravitasi secara langsung dari biner lubang hitam dan bintang neutron menjadi kesempatan untuk dapat menguji teori gravitasi yang sedang dikembangkan.Gelombang gravitasi secara umum dipengaruhi oleh modifikasi teori gravitasi selama penjalarannya pada jarak kosmologi. Dengan membandingkan persamaan gelombang gravitasi dengan teori modifikasi yang dikembangkan, diperoleh persamaan umum gelombang gravitasi dari teori gravitasi yang dikembangkan. Pada artikel ini diperoleh persamaan gelombang gravitasi untuk teori Proca yang digeneralisasi. Dapat disimpulkan bahwa fungsi yang mengandung vektor medan masif dapat mempengaruhi gelombang gravitasi. Persamaan ini dapat digunakan untuk menguji teori Proca yang digeneralisasi.</p>

scholarly journals ASTROPHYSICAL CONDITION ON THE ATTOLENSING AS A POSSIBLE PROBE FOR A MODIFIED GRAVITY THEORY

2008 ◽  
Vol 23 (01) ◽  
pp. 167-179
Author(s):  
TAKAHIRO SATO ◽  
BOBBY E. GUNARA ◽  
KAZUHIRO YAMAMOTO ◽  
FREDDY P. ZEN
Keyword(s):  
Black Hole ◽  
Relative Motion ◽  
Gravitational Lensing ◽  
Modified Gravity ◽  
Source Size ◽  
Gravity Theory ◽  
Solar Mass ◽  
Wave Effect ◽  
Modified Gravity Theory ◽  
Astrophysical Condition

We investigate the wave effect in the gravitational lensing by a black hole with very tiny mass less than 10-19 M sun (solar mass), which is called attolensing, motivated by a recent report that the lensing signature might be a possible probe of a modified gravity theory in the braneworld scenario. We focus on the finite source size effect and the effect of the relative motion of the source to the lens, which are influential to the wave effect in the attolensing. Astrophysical condition that the lensed interference signature can be a probe of the modified gravity theory is demonstrated. The interference signature in the microlensing system is also discussed.

scholarly journals Gravitational waves in metric-affine gravity theory

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
Alejandro Jiménez-Cano ◽  
Yuri N. Obukhov
Keyword(s):  
Gravitational Waves ◽  
Gravity Theory ◽  
Affine Gravity

scholarly journals A Modified Gravity Theory: Null Aether

2019 ◽  
Vol 71 (3) ◽  
pp. 312 ◽  
Author(s):  
Metin Gürses ◽  
Çetin Şentürk
Keyword(s):  
Modified Gravity ◽  
Gravity Theory ◽  
Modified Gravity Theory

scholarly journals Polarized Initial States of Primordial Gravitational Waves

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 672
Author(s):  
Sugumi Kanno ◽  
Jiro Soda
Keyword(s):  
Gravitational Waves ◽  
Modified Gravity ◽  
Coherent States ◽  
Inflationary Universe ◽  
Dynamical Generation ◽  
Primordial Gravitational Waves ◽  
Initial States ◽  
Matter Fields

Polarizations of primordial gravitational waves can be relevant when considering an inflationary universe in modified gravity or when matter fields survive during inflation. Such polarizations have been discussed in the Bunch–Davies vacuum. Instead of taking into account the dynamical generation of polarizations of gravitational waves, in this paper, we consider polarized initial states constructed from S U ( 2 ) coherent states. We then evaluate the power spectrums of the primordial gravitational waves in the states.

scholarly journals Modifications to Plane Gravitational Waves from Minimal Lorentz Violation

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1318 ◽  
Author(s):  
Rui Xu
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Lorentz Invariance ◽  
Lorentz Violation ◽  
First Order ◽  
Test Particles ◽  
Violation Of Lorentz Invariance ◽  
Plane Gravitational Waves ◽  
Wave Modes

General Relativity predicts two modes for plane gravitational waves. When a tiny violation of Lorentz invariance occurs, the two gravitational wave modes are modified. We use perturbation theory to study the detailed form of the modifications to the two gravitational wave modes from the minimal Lorentz-violation coupling. The perturbation solution for the metric fluctuation up to the first order in Lorentz violation is discussed. Then, we investigate the motions of test particles under the influence of the plane gravitational waves with Lorentz violation. First-order deviations from the usual motions are found.

scholarly journals Anti-screening of the Galileon force around a disk center hole

2019 ◽  
Vol 34 (02) ◽  
pp. 1950013 ◽  
Author(s):  
Hiromu Ogawa ◽  
Takashi Hiramatsu ◽  
Tsutomu Kobayashi
Keyword(s):  
Field Equation ◽  
Scalar Field ◽  
Modified Gravity ◽  
Disk Center ◽  
Academic Interest ◽  
Screening Effect ◽  
Matter Source ◽  
Fifth Force ◽  
Scalar Field Equation

The Vainshtein mechanism is known as an efficient way of screening the fifth force around a matter source in modified gravity. This has been verified mainly in highly symmetric matter configurations. To study how the Vainshtein mechanism works in a less symmetric setup, we numerically solve the scalar field equation around a disk with a hole at its center in the cubic Galileon theory. We find, surprisingly, that the Galileon force is enhanced, rather than suppressed, in the vicinity of the hole. This anti-screening effect is larger for a thinner, less massive disk with a smaller hole. At this stage, our setup is only of academic interest and its astrophysical consequences are unclear, but this result implies that the Vainshtein screening mechanism around less symmetric matter configurations are quite nontrivial.

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