scholarly journals Gravitational waves in massive conformal gravity

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
F. F. Faria
Keyword(s):  
Plane Wave ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Binary Systems ◽  
Plane Waves ◽  
Graviton Mass ◽  
Conformal Gravity ◽  
Physical Plane ◽  
Field Equations ◽  
Plane Wave Solution

Abstract First, we obtain the plane wave solution of the linearized massive conformal gravity field equations. It is shown that the theory has seven physical plane waves. In addition, we investigate the gravitational radiation from binary systems in massive conformal gravity. We find that the theory with large graviton mass can reproduce the orbit of binaries by the emission of gravitational waves.

Gravitational waves in general relativity III. Exact plane waves

1959 ◽  
Vol 251 (1267) ◽  
pp. 519-533 ◽  
Keyword(s):  
Plane Wave ◽  
Gravitational Waves ◽  
Electromagnetic Waves ◽  
Plane Waves ◽  
Flat Space ◽  
Field Equations ◽  
Test Particles ◽  
Wave Space ◽  
General Plane ◽  
Plane Gravitational Waves

Plane gravitational waves are here defined to be non-flat solutions of Einstein’s empty spacetime field equations which admit as much symmetry as do plane electromagnetic waves, namely, a 5-parameter group of motions. A general plane-wave metric is written down and the properties of plane wave space-times are studied in detail. In particular, their characterization as 4 plane ’ is justified further by the construction of 4 sandwich waves ’ bounded on both sides by (null) hyperplanes in flat space-time. It is shown that the passing of a sandwich wave produces a relative acceleration in free test particles, and inferred from this that such waves transport energy.

Spherical gravitational waves

1959 ◽  
Vol 251 (994) ◽  
pp. 233-271 ◽  
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Large Class ◽  
Linear Approximation ◽  
Gravitational Radiation ◽  
Gravitational Mass ◽  
Field Equations ◽  
Spherical Waves ◽  
Non Linear ◽  
External Forces

The field of gravitational radiation emitted from two moving particles is investigated by means of general relativity. A method of approximation is used, and in the linear approximation retarded potentials corresponding to spherical gravitational waves are introduced. As is already known, the theory in this approximation predicts that energy is lost by the system. The field equations in the second, non-linear, approximation are then considered, and it is shown that the system loses an amount of gravitational mass precisely equal to the energy carried away by the spherical waves of the linear approximation. The result is established for a large class of particle motions, but it has not been possible to determine whether energy is lost in free gravitational motion under no external forces. The main conclusion of this work is that, contrary to opinions frequently expressed, gravitational radiation has a real physical existence, and in particular, carries energy away from the sources.

scholarly journals Gravitational waves — A review on the theoretical foundations of gravitational radiation

2018 ◽  
Vol 33 (14n15) ◽  
pp. 1830013 ◽  
Author(s):  
Alain Dirkes
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Wave Zone ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Radiative Losses ◽  
Zone Field ◽  
Theoretical Foundations

In this paper, we review the theoretical foundations of gravitational waves in the framework of Albert Einstein’s theory of general relativity. Following Einstein’s early efforts, we first derive the linearized Einstein field equations and work out the corresponding gravitational wave equation. Moreover, we present the gravitational potentials in the far away wave zone field point approximation obtained from the relaxed Einstein field equations. We close this review by taking a closer look on the radiative losses of gravitating [Formula: see text]-body systems and present some aspects of the current interferometric gravitational waves detectors. Each section has a separate appendix contribution where further computational details are displayed. To conclude, we summarize the main results and present a brief outlook in terms of current ongoing efforts to build a spaced-based gravitational wave observatory.

Conservation laws and gravitational radiation

1977 ◽  
Vol 55 (15) ◽  
pp. 1342-1348 ◽  
Author(s):  
Peter Rastall
Keyword(s):  
Conservation Laws ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Lagrangian Density ◽  
Total Stress ◽  
Field Equations ◽  
Gravitational Fields ◽  
Previous Version ◽  
Newtonian Approximation

A total stress-momentum is defined for gravitational fields and their sources. The Lagrangian density is slightly different from that in the previous version of the theory, and the field equations are considerably simplified. The post-Newtonian approximation of the theory is unchanged. The existence and nature of weak gravitational waves are discussed.

scholarly journals GRAVITATIONAL WAVES FROM COALESCING BINARY SOURCES

2010 ◽  
Vol 19 (14) ◽  
pp. 2295-2298 ◽  
Author(s):  
M. D. MAIA
Keyword(s):  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Theoretical Basis ◽  
Binary Systems ◽  
Translational Symmetry ◽  
Axially Symmetric ◽  
Poincaré Symmetry ◽  
Group Of Isometries ◽  
Coalescing Binary Systems ◽  
Binary Sources

Coalescing binary systems (e.g. pulsars, neutron stars and black holes) are currently considered to be the most likely sources of gravitational radiation, yet to be detected on or near Earth, where the local gravitational field is negligible and the Poincaré symmetry rules. On the other hand, the general theory of gravitational waves emitted by axially symmetric rotating sources predicts the existence of a nonvanishing news function. The existence of such function implies that, for a distant observer, the asymptotic group of isometries, the BMS group, has a translational symmetry that depends on the orbit periodicity of the source, thus breaking the isotropy of the Poincaré translations. These results suggest that the asymptotic BMS-covariant wave equation should be applied to obtain a proper theoretical basis for the gravitational waves observations from those binary sources.

scholarly journals The gravitational radiation power of the blazar OJ 287

2020 ◽  
Vol 4 (4) ◽  
pp. 397-411
Author(s):  
A. E. Volvach ◽  
◽  
L. N. Volvach ◽  
M. G. Larionov ◽  
◽  
...  
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Binary Systems ◽  
Radiation Power ◽  
Close Binary ◽  
Frequency Monitoring ◽  
Radio Band ◽  
Harmonic Analyses ◽  
Blazar Oj 287

Using a new model based on the consideration of close binary systems (CDS) of supermassive black holes (SMBHs), we obtained data for the OJ 287 blazar, which is necessary for finding the parameters of the OJ 287 gravitational radiation. We used the results of multi-frequency monitoring performed only in the radio band. The application of harmonic analyses of observational data allowed us to construct a model of CDS consisting of two SMBHs of comparable masses, which made it possible to find the power of gravitational radiation coming from OJ 287, variations in the orbit of the double SMDS, and to consider the possibility of experimentally determining changes in these parameters in the system. Variants of radiation of electromagnetic and gravitational waves coming from OJ 287 in various states of object activity are considered.

Gravitational waves

2019 ◽  
pp. 72-79
Author(s):  
Steven Carlip
Keyword(s):  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Field Approximation ◽  
Weak Field ◽  
Quadrupole Moments ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Compact Binary ◽  
Speed Of Gravity ◽  
Weak Field Approximation

In the weak field approximation, the Einstein field equations can be solved, and lead to the prediction of gravitational waves. After showing that gravitational radiation depends on changing quadrupole moments, this chapter describes the production, propagation, and detection of gravitational waves. It includes discussions of the speed of gravity, detectors, the “chirp” waveform for a compact binary system, and the nature of astrophysical sources.

Electromagnetic waves

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Plane Wave ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Plane Waves ◽  
Geometrical Optics ◽  
Particle Detection ◽  
Spatial Coordinates ◽  
A Charge

This chapter examines solutions to the Maxwell equations in a vacuum: monochromatic plane waves and their polarizations, plane waves, and the motion of a charge in the field of a wave (which is the principle upon which particle detection is based). A plane wave is a solution of the vacuum Maxwell equations which depends on only one of the Cartesian spatial coordinates. The monochromatic plane waves form a basis (in the sense of distributions, because they are not square-integrable) in which any solution of the vacuum Maxwell equations can be expanded. The chapter concludes by giving the conditions for the geometrical optics limit. It also establishes the connection between electromagnetic waves and the kinematic description of light discussed in Book 1.

scholarly journals Ultrasonic Scattered Field Distribution of One and Two Cylindrical Solids with Phased Array Technique

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Xiaozhou Liu ◽  
Jian Ma ◽  
Haibin Wang ◽  
Sha Gao ◽  
Yifeng Li ◽  
...  
Keyword(s):  
Plane Wave ◽  
Field Distribution ◽  
Scattered Field ◽  
Phased Array ◽  
Simulation Analysis ◽  
Plane Waves ◽  
Theoretical Solution ◽  
Steel Matrix ◽  
Field Distributions ◽  
Scattered Fields

AbstractThe scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.

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