Gravitational Wave Pulse Research Articles

A generic test of modified gravity models which emulate dark matter

We propose a generic test for models in which gravity is modified to do away with dark matter. These models tend to have gravitons couple to a different metric than ordinary matter. A strong test of such models comes from comparing the arrival time of the gravitational wave pulse from a cosmological event such as a supernova with the arrival times of the associated pulses of neutrinos and photons. For SN 1987a we show that the gravity wave would have arrived 5.3 days after the neutrino pulse.

General relativistic forces

Einstein proposed his general theory of relativity in 1916 and showed that the rotation rate of the perihelion of Mercury agrees with his theory. Until now, the gravitational lens effect and the gravitational red-shift were the only experimental proofs of Einstein's theory of general relativity. Einstein assumed that the speed of light is an ultimate speed and nothing can exceed it. Even gravity cannot propagate faster than the speed of light. Thus, a gravito-radiative force is predicted as a retardation correction to the Newtonian gravitational force and as a far-field force carried by a gravitational wave (pulse). The gravitational pulse accelerates the orbital motion of the moon and this is detected as an irregularity of the length of day. The theory of the creation of spiral galaxies in terms of the gravito-radiative force generated by colliding black holes is presented. In this theory each spiral galaxy is expected to have 180 ∘ rotational symmetry, therefore, the number of spiral arms must be even. Time-independent Einstein theory predicts anisotropy in the speed of light and an anomaly in the gravitational constant of the deuteron.

On the motion of spinning test particles inplane gravitational waves

The Mathisson-Papapetrou-Dixon equations for a massivespinning test particle in plane gravitational waves are analysed andexplicit solutions constructed in terms of solutions of certain linearordinary differential equations. For harmonic waves this system reducesto a single equation of Mathieu-Hill type. In this case spinning particlesmay exhibit parametric excitation by gravitational fields. For a spinningtest particle scattered by a gravitational wave pulse, the finalenergy-momentum of the particle may be related to the width, height,polarization of the wave and spin orientation of the particle.

A neutron star collapse induced by a primordial black hole as the source of cosmological γ-ray bursts

A novel scenario is proposed for the origin of cosmological γ-ray bursts relating them with the induced collapse of an isolated neutron star under the action of a primordial black hole inside it. A mechanism is pointed out for black hole capturing into bounded orbits in a contracting protostellar cloud (which further evolves to a neutron star), and it is shown that this mechanism is most efficient in the pregalactic epoch. The qualitative results of neutrino transfer calculations are presented; these neutrinos originate from the quark phase transition in the nucleon matter which takes place in the accretion flow in the interior of the star. The neutrinos and antineutrinos escaping from a dense nucleon matter are degenerate and annihilate in the immediate vicinity of the star surface where an inverse temperature layer in the outstreaming electron-positron wind is produced. This layer acts as a natural barrier against baryon pollution and gives rise to a very high (≈ 103) value of the Lorentz factor in the expanding plasma, in agreement with the observed energy and duration of the process. This makes it possible to explain the main properties of the γ-ray bursts. We also consider other important features of this scenario, including the predominantly extragalactic origin of the bursts, the apparent absence of the cosmological time dilation, the excess drop in the number of bursts—luminosity dependence for z>0.7, and the unlikely corrllation between the burst and the gravitational wave pulse.

Dynamics of perturbations of rotating black holes

We present a numerical study of the time evolution of perturbations of rotating black holes. The solutions are obtained by integrating the Teukolsky equation written as a first-order in time, coupled system of equations, in a form that explicitly captures its hyperbolic structure. We address the numerical difficulties of solving the equation in its original form. We follow the propagation of generic initial data through the burst, quasinormal ringing and power-law tail phases. In particular, we calculate the effects due to the rotation of the black hole on the scattering of incident gravitational wave pulses. These results may help explain how the angular momentum of the black hole affects the gravitational waves that are generated during the final stages of black hole coalescence.

Theory of spacecraft Doppler tracking

We present a review of the spacecraft Doppler tracking technique used in broad band searches for gravitational waves in the millihertz frequency band. After deriving the transfer functions of a gravitational wave pulse and of the noise sources entering in

Long-term operation of the Rome "Explorer" cryogenic gravitational wave detector.

We describe the cryogenic resonant gravitational wave detector of the Rome group, named Explorer, and report on its long term operation with sensitivity for short bursts in the range $h\ensuremath{\simeq}7\ensuremath{-}10\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}$. Explorer has mass $M=2270$ kg and is equipped with a resonant capacitive transducer followed by a dc superconducting quantum interference device amplifier. It has been operated at $T\ensuremath{\simeq}2.6$ K in a cryostat cooled with superfluid helium. With a transducer voltage bias of 320 V ($E=6.15$ MV/m) the two resonant modes have frequencies of 904.7 and 921.3 Hz with coupled quality factors, respectively, of 0.77\ifmmode\times\else\texttimes\fi{}${10}^{6}$ and 1.0\ifmmode\times\else\texttimes\fi{}${10}^{6}$. The description of the experimental apparatus and of its calibration is followed by the analysis of the noise and the calculation of the expected sensitivity of the detector: $h\ensuremath{\simeq}8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}$ (under the assumption of bursts with duration of 1 ms). We then describe the data acquisition system and the techniques of data analysis, discussing the filtering algorithms. The last section reports the experimental results obtained during the operation of the detector from May 1990 to December 1991. During this period the data were recorded for more than two-thirds of the total time: we show the distributions of the data and the hourly averages of the sensitivity. The data taken from May 1991 to December 1991 have also been used to establish a new improved upper limit for the rate and strength of gravitational wave pulses; at $h=2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$, for example, there are no more than 0.5 events/day as averaged over a period of 134 days.

Penrose's quasi-local mass and cylindrically symmetric spacetimes

Penrose's quasi-local mass is calculated for a cylinder of finite length in a cylindrically symmetric spacetime. For a cylindrically symmetric gravitational wave pulse, the mass associated with a finite cylinder is seen to rise and fall with the passage of the wave. In general, the mass has a dependence on the length of the cylinder which is related to the potential energy.

The gravitational faraday rotation for cylindrical gravitational solitons

By using cylindrical soliton solutions, the nonlinear behavior of gravitational waves in vacuum is studied in terms of a rotation of the polarization vector between two independent modes. This effect was emphasized by Piran, Safier, and Stark as a gravitational analogue of the Faraday rotation. The polarization of the soliton wave is calculated, and it is found that the+mode which was dominant near the axis of symmetry is fully converted to the×mode at some interaction region and then the disturbance propagating along a light cone like a gravitational wave pulse contains both polarizations.

Coincidence techniques for gravitational wave experiments

A new method is proposed for coincidence analyses of gravitational wave data. It consists in taking the sum of the signals of the two (or more) antennas, finding its distribution and comparing it with the distribution of the sum that is obtained when the data set of one antenna is shifted by a time δt with respect to the other set. If the two antennas are identical, the standard coincidence method is better. But the new method has to be preferred to the standard one, whenever the signals produced by a gravitational wave pulse in the two (or more) antennas differ by more than a factor 1.5. This is very likely because of differences in the antenna resonance frequencies and because of the different location and orientation of the antennas on the Earth.

Estimate of the cosmic ray background in an interferometric antenna for gravitational wave detection

The effect of the cosmic ray interaction in the masses of an interferometric antenna for gravitational wave (GW) detection is evaluated. In a 3 km antenna this background, mainly due to muons gives a limit, for 1 ms GW pulses, of h∼8.5×10 -23 with a frequency of 2×10 -1 events/year and 8.5×10 -26 with 4.1×10 -6 events/year. For GW having frequency>10 Hz the sensitivity limit is h∼1.7×10 -31. This background seems to allow unshielded operation of the interferometer test masses.

Gravitational wave pulse and soliton wave collision.

We study the collision of a gravitational wave pulse and a soliton wave on a spatially homogeneous background. This collision is described by an exact solution of Einstein's equations in a vacuum which is generated from a nondiagonal seed by means of a soliton transformation. The effect produced by the soliton on the amplitude and polarization of the wave is considered.

Gravitational wave pulse in a spatially homogeneous universe

An exact solution of the Einstein field equations with perfect fluid source is interpreted as a gravitational wave pulse propagating in a spatially homogeneous spacetime. By studying the matter density of the fluid, we reach the conclusion that if the model universe is expanding the perfect fluid loses energy as a result of the passage of the wave pulse, while if the universe is contracting the opposite occurs. We also study the effect of the wave pulse on the kinematics of the fluid and on the curvature and conformal curvature of the hypersurfaces orthogonal to the fluid flow.

Observational status of black holes

There might be ca. 10 9 stellar-mass black holes - the remnants of massive stars - in our own Galaxy. Unless one is lucky enough to record the gravitational wave pulse signalling their formation, the prospects for detection are remote except for the small fraction th at happen to lie in close binary systems. In such systems, gas captured from the companion star emits X-rays as it swirls inward towards the hole. Cygnus X - 1 has been for some years the best candidate: its mass is estimated as ≥ 6 M ⊙ and the X-rays vary irregularly on timescales th at may be as short as milliseconds. An interesting recent development has been the detection of rapid irregular fluctuations from Circinus XI (Toor 1977), which may be a system similar to Cygnus X - 1. When Cygnus X - 1 is no longer a unique well-studied object, but is established as merely one of a class, it will seem less plausible to advocate ‘ ad hoc ´ models (involving for instance ‘ third bodies ’ in the system) as serious alternative to a black hole interpretation. The current lull in X-ray astronomy should soon end with the results from High Energy Astronomical Observatories 1 and 2.

The Munich gravitational-wave detector

With the Munich-Frascati detector pair the limit of detectable pulse strengths for short gravitational-wave pulses could be reduced to a few 105 erg/cm2 Hz by improvement of the mechanical and electrical set-up. For given dimensions of the bar, the sensitivity is shown to be very close to the theoretical limit, set only by the properties of the available piezomaterial.

Cylinders as gravitational radiation telescopes

view Abstract Citations (5) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cylinders as gravitational radiation telescopes. Hier, R. G. ; Rasband, S. N. Abstract The multitude of resonance modes of a free elastic cylinder are viewed as a host of resonant detectors for gravitational radiation. The absorption cross sections for all modes using exact cylinder eigensolutions are obtained, and detailed numerical results for the axisymmetric longitudinal modes in the Pochhammer-Chree approximation are presented. The combining of information from all modes excited by a gravitational wave pulse to give spectra and directional information about the incident burst is discussed. Publication: The Astrophysical Journal Pub Date: January 1975 DOI: 10.1086/153350 Bibcode: 1975ApJ...195..507H Keywords: Absorption Cross Sections; Elastic Cylinders; Gravitational Waves; Radiation Detectors; Vibration Mode; Eigenvalues; Numerical Analysis; Pulsed Radiation; Resonant Frequencies; Telescopes; Astrophysics full text sources ADS |

On the method of virtual quanta and gravitational radiation

We extend the Weizsäeker-Williams method of virtual quanta to the domain of gravitational encounters and set up a correlation between collision problems and the corresponding interaction of gravitational radiation. In the local rest frame of a relativistic test particle the gravitational field of a Schwarzschild mass consists predominantly of a pulse of plane-fronted gravitational waves. We Fourier analyse this equivalent pulse and consider the scattering of each frequency component, virtual quanta, by the test body. The scattering by the long-range Newtonian-type field of a point particle is described by the analogue of the Rutherford cross-section. The escape of this scattered flux to infinity, suitably transformed, gives us the radiative loss of gravitational energy by a rapidly moving particle. The radiation spectrum and total energy radiated in a distant brehmsstrahlung encounter are computed as an example.

The Method of Virtual Quanta and Gravitational Radiation

We extend the Weizsäcker-Williams method to the domain of gravitational encounters and correlate collision problems with the corresponding interaction of gravitational radiation. To an ultra-relativistic test particle the field of a Schwarzschild mass appears as a pulse of gravitational plane waves. We consider the scattering of each Fourier component, virtual quanta, by the Newtonian-type field of the test body. The scattered flux at infinity gives us the radiative loss of gravitational energy by a rapidly moving particle.

Does the Cylindrically Symmetric Gravitational Wave Pulse Carry Energy?

Does the Cylindrically Symmetric Gravitational Wave Pulse Carry Energy?