scholarly journals Erratum: Dispersion of gravitational waves in cold spherical interstellar medium

2020 ◽  
Vol 29 (13) ◽  
pp. 2092001
Author(s):  
Dániel Barta ◽  
Mátyás Vasúth
Keyword(s):  
Interstellar Medium ◽  
Frequency Shift ◽  
Gravitational Waves ◽  
Conversion Factor ◽  
Junction Conditions ◽  
Transient Event ◽  
Numerical Errors ◽  
Numerical Result ◽  
Metric Functions

The study published in IJMPD 27(4):1850040, 2018 provided a numerical result for the frequency-shift of GWs due to dispersion in interstellar medium. In order to adjust the metric functions of the originally improperly matched ‘background’ spacetime in Sec. 2.1, the authors have adopted Darmois–Israel junction conditions. In Sec. 4.1 the code used in the original paper erroneously computed the magnitude of frequency-shift for the transient event GW150914 due to a missing conversion factor. In both cases where numerical errors and potential contradictions have been identified and eliminated, adjustments were undertaken in order to maintain consistency with closely-related earlier studies.

Noether symmetries of vacuum classes of pp-waves and the wave equation

2016 ◽  
Vol 13 (09) ◽  
pp. 1650109 ◽  
Author(s):  
Sameerah Jamal ◽  
Ghulam Shabbir
Keyword(s):  
Wave Equation ◽  
Gravitational Waves ◽  
Wave Equations ◽  
Noether Symmetry ◽  
Symmetry Groups ◽  
Noether Symmetries ◽  
Noether’S Theorem ◽  
Metric Functions ◽  
Symmetry Algebras

The Noether symmetry algebras admitted by wave equations on plane-fronted gravitational waves with parallel rays are determined. We apply the classification of different metric functions to determine generators for the wave equation, and also adopt Noether's theorem to derive conserved forms. For the possible cases considered, there exist symmetry groups with dimensions two, three, five, six and eight. These symmetry groups contain the homothetic symmetries of the spacetime.

On the dispersion of cylindrical impulsive gravitational waves

1987 ◽  
Vol 412 (1842) ◽  
pp. 75-91 ◽  
Keyword(s):  
Exact Solution ◽  
Wave Packet ◽  
Gravitational Waves ◽  
Time Derivative ◽  
Radial Distance ◽  
Space Time ◽  
Principal Feature ◽  
Metric Functions ◽  
Metric Function ◽  
Weyl Scalar

An exact solution, describing the dispersion of a wave packet of gravita­tional radiation, having initially (at time t = 0) an impulsive character, is analysed. The impulsive character of the wave-packet derives from the space-time being flat, except at a radial distance ϖ = ϖ 1 (say) at t = 0, and the time-derivative of the Weyl scalars exhibiting δ-function singu­larities at ϖ = ϖ 1 , when t → 0. The principal feature of the dispersion is the development of a singularity of the metric function, v , and of the Weyl scalar, ψ 2 , when the wave, after reflection at the centre, collides with the still incoming waves. The evolution of the metric functions and of the Weyl scalars, as the dispersion progresses, is illustrated graphically.

scholarly journals Relation between Planck’s Constant and Speed of Light, Predicting Proton Radius More Accurately

2019 ◽  
Vol 11 (5) ◽  
pp. 1
Author(s):  
Anna C. M. Backerra
Keyword(s):  
Gravitational Waves ◽  
Conversion Factor ◽  
Elementary Particles ◽  
Accurate Prediction ◽  
Quantum Mechanical ◽  
Speed Of Light ◽  
Proton Radius ◽  
Definition Of ◽  
Physical Phenomena ◽  
Theoretical Results

In twin physics, descriptions of phenomena on a quantum-mechanical as well as astronomical scale are reconciled by considering them in a complementary way. This is in agreement with the view of Heisenberg and carried out by using the definition of complementarity as given by Max Jammer. The obtained theoretical results can be identified with basic physical phenomena like the forces of nature, a series of elementary particles and gravitational waves. If the proton as described by twin physics is combined with the early ideas of Einstein about the energetic equivalence of mass and radiation, a relation between the Planck’s constant and the speed of light is found, in which the mass and radius of the proton occur, together with a factor four. This factor acts as a conversion factor from mass to radiation. Besides of that, this relation leads to a more accurate prediction of the radius of the proton.

scholarly journals Collapsing stellar filament and exotic matter in Palatini f(R) gravity

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Rubab Manzoor ◽  
Abdul Jawad ◽  
Muhammad Adeel ◽  
Muhammad Saeed ◽  
Shamaila Rani
Keyword(s):  
Gravitational Waves ◽  
Radial Pressure ◽  
Surface Boundary ◽  
Baryonic Matter ◽  
Junction Conditions ◽  
Stability Criteria ◽  
Theoretical Relation ◽  
Gravitational Effects ◽  
Proportional Relation ◽  
The Stability

Abstract We explore the dynamics of collapsing stellar filament in the presence of exotic material like dark matter. We use Palatini f(R) theory to include exotic substance in the collapsing process. We derive a collapse equation by applying Darmois junction conditions on collapsing surface boundary $$\Sigma $$Σ. It is found that the radial pressure related to baryonic matter remains non-zero at $$\Sigma $$Σ. We then discuss the stability criteria of the collapsing process in the framework of three parameteric model, $$f(R)=R+\lambda R_{c}[ 1-(1+\frac{R^{2}}{R^{2}_{c}})^{-n}]$$f(R)=R+λRc[1-(1+R2Rc2)-n]. It is concluded that the stability of collapsing filament depends upon a directly proportional relation of gravitational effects of exotic terms with the radial pressure of seen matter. Stability criteria of family of polytropic filamentary structures are also discussed. For all stable polytropic filaments, it is found that the density of seen material is exponentially related to the exotic forces. Finally, we explore theoretical relation between gravitational waves and dark terms. It is theoretically predicted that the presence of exotic material can affect the propagation of gravitational waves.

scholarly journals ON THE FREQUENCY SHIFT OF GRAVITATIONAL WAVES

2010 ◽  
Vol 25 (17) ◽  
pp. 1455-1465
Author(s):  
CLAUDIO M. G. DE SOUSA
Keyword(s):  
Frequency Shift ◽  
Gravitational Waves ◽  
Flat Spacetime ◽  
The Earth ◽  
Starting Point ◽  
Plane Gravitational Waves ◽  
Noise Filters

Considering plane gravitational waves propagating through flat spacetime, it is shown that curvatures experienced both in the starting point and during their arrival at the earth can cause a considerable shift in the frequencies as measured by earth and space-based detectors. In particular for the case of resonant bar detectors this shift can cause noise-filters to smother the signal.

A GENERALIZED VACUOLE MODEL IN HIGHER DIMENSIONS

2003 ◽  
Vol 12 (06) ◽  
pp. 1035-1045
Author(s):  
A. BANERJEE ◽  
S. CHATTERJEE
Keyword(s):  
Exact Solution ◽  
Frequency Shift ◽  
Initial Conditions ◽  
Dynamical Behavior ◽  
Boundary Surface ◽  
Blue Shift ◽  
Higher Dimensions ◽  
Junction Conditions ◽  
Higher Dimensional ◽  
Arbitrary Dimensions

We extend to higher dimensions a recent work of Bonnor, which generalizes the Einstein–Straus model utilizing the inhomogeneous Tolman–Bondi universe in place of the homogeneous Friedmann one. Following Israel's junction conditions, the criteria of matching between the higher dimensional Schwarzschild-like interior and the Tolman–Bondi-like exterior is obtained. We also give a new exact solution for a five-dimensional TB type of metric and use it to study the dynamical behavior of the vacuole boundary. Furthermore the transformation relations which transform the inhomogeneous TB metric to the homogeneous Friedmann model are explicitly given for any arbitrary dimensions. The frequency shift of radiation coming from the boundary surface is calculated and it is found that, depending on initial conditions both redshift and blue-shift are possible for an expanding vacuole. This is at variance with Bonnor's result where only redshift is possible under similar situation. It is also observed that higher dimensional models are less stable against perturbation than the usual 4D ones.

SPECTRAL SHIFT FROM AN EVOLVING DUST SPHERE

1993 ◽  
Vol 02 (04) ◽  
pp. 489-495 ◽  
Author(s):  
B. BHUI ◽  
S. CHATTERJEE ◽  
A. BANERJEE
Keyword(s):  
Frequency Shift ◽  
Higher Dimensions ◽  
Spectral Shift ◽  
Symmetric Distribution ◽  
Spherically Symmetric ◽  
Junction Conditions ◽  
Exterior Solution ◽  
Spherically Symmetric Distribution

Following O’brien-Synge’s junction conditions we find an exterior solution for a (n+2)-dimensional spherically symmetric distribution in comoving coordinates and match it with the zero-pressure dust interior. An expression for Schwarzschild-like mass is also obtained from the conditions of fit at the boundary. The relevant transformation relations which recast the comoving exterior into the static Schwarzschild-like form are also obtained. This generalizes to higher dimensions an earlier work of Raychaudhuri in 4D spacetime. Utilizing the transformation relations, an expression for frequency shift of radiation emitted from the surface of the sphere is also obtained.

scholarly journals Pulsars are cool. Seriously.

2012 ◽  
Vol 8 (S291) ◽  
pp. 3-10 ◽  
Author(s):  
Scott M. Ransom
Keyword(s):  
General Relativity ◽  
Interstellar Medium ◽  
Gravitational Waves ◽  
Stellar Evolution ◽  
Direct Detection ◽  
Dense Matter ◽  
Tests Of General Relativity ◽  
The Future ◽  
Basic Physics ◽  
Over 40 Years

AbstractEver since the first pulsar was discovered by Bell and Hewish over 40 years ago, we've known that not only are pulsars fascinating and truly exotic objects, but that we can use them as powerful tools for basic physics and astrophysics as well. Taylor and Hulse hammered these views home with their discovery and timing of the spectacular “binary pulsar” in the 1970s and 1980s. In the last two decades a host of surprises and a promise of phenomenal scientific riches in the future has come from the millisecond pulsars. As our instrumentation has become more sensitive and better suited to measuring the pulses from these objects, they've given us new tests of general relativity, fantastic probes of the interstellar medium, constraints on the physics of ultra-dense matter, new windows into binary and stellar evolution, and the promise of a direct detection of gravitational waves. These things really are cool, and there is much more we will do with them in the future.

Current status of special planetary and lunar theories and ephemerides

1966 ◽  
Vol 25 ◽  
pp. 266-267
Author(s):  
R. L. Duncombe
Keyword(s):  
Observational Data ◽  
Current Status ◽  
Numerical Errors

An examination of some specialized lunar and planetary ephemerides has revealed inconsistencies in the adopted planetary masses, the presence of non-gravitational terms, and some outright numerical errors. They should be considered of temporary usefulness only, subject to subsequent amendment as required for the interpretation of observational data.

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