Gravitational radiation.
Gravitational radiation measurements by HF GRAVITATIONAL wave detector
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Gravitational radiation detectors
Gravitational radiation antennas for detecting very small dynamic gravitational gradients
ANTENNA↗
Gravitational radiation from rotating gravitational collapse
The efficiency of gravitational wave emission from axisymmetric rotating collapse to a black hole was found to be very low: Delta E/Mc sq. less than 7 x 10(exp -4). The main waveform shape is well defined and nearly independent of the details of the collapse. Such a signature will allow pattern recognition techniques to be used when searching experimental data. These results (which can be scaled in mass) were obtained using a fully general relativistic computer code that evolves rotating axisymmetric configurations and directly computes their gravitational radiation emission.
Stark, Richard F.↗
The approximation of radiative effects in relativistic gravity - Gravitational radiation reaction and energy loss in nearly Newtonian systems
An argument is presented to determine the accuracy with which a solution of Einstein's field equations of gravitation must be approximated in order to describe the dominant effects of gravitational radiation emission from weak-field systems. Several previous calculations are compared in the light of this argument, and some apparent discrepancies among them are resolved. The majority of these calculations support the 'quadrupole formulae' for gravitational radiation energy loss and radiation reaction.
Walker, M.↗
Spacecraft to Spacecraft Coherent Laser Tracking as a Xylophone Interferometer Detector of Gravitational Radiation
Searches for gravitational radiation can be performed in space with two spacecraft tracking each other with coherent laser light. This experimental technique could be implemented with two spacecraft carrying an appropriate optical payload, or with the proposed broad-band, space-based laser interferometer detectors of gravitational waves operated in this non-interferometric mode.
interferometer↗
Determining gravitational radiation from Newtonian self-gravitating systems
Quadrupole gravitational radiation formulas are tested and compared in a calculation of rotating stellar core collapse. While the standard quadrupole formula (SQF) allows an economical calculation of the waveform in postlinear gravity, it has several shortcomings that become apparent in a finite difference (FD) calculation. These shortcomings are related to the large-moment arm of the quadrupole moment and the two (numerical) time derivatives that separate it from the waveform. These shortcomings lead to high-frequency noise in the SQF waveform. Several alternatives to the SQF are developed. Each is mathematically equivalent to the SQF and applicable to self-gravitating sources. For FD calculations, the new quadrupole formulas are all superior to the SQF and capable of producing waveforms free of the high-frequency noise characteristics of its use.
Finn, Lee Samuel↗
<study on theoretical and experimental research on gravitational radiation< progress report
Gravitational radiation - closed loop servosystems for LaCoste Romberg gravimeter
GRAVIMETER↗
Gravitational radiation as a test of relativistic gravity
Gravitational radiation can be used to test theories of gravitation. When the waves are ultimately detected directly, their speed and polarization properties can be measured and compared with predictions of alternative theories. The multipole nature of gravitational radiation was already tested in the binary pulsar, where observations of the decay of the orbit verify the quadrupole formula for gravitational radiation damping of general relativity and put strong constraints on dipole gravitational radiation predicted by many alternative theories.
Will, Clifford M.↗
Competition of neutrino and gravitational radiation in neutron star formation
An investigation is conducted concerning the possibility that neutrino radiation rather than gravitational radiation may be the dominant way by which nonradial pulsations are damped out in a collapsing star. The effects of neutrino radiation on the nonradial oscillations of such objects are examined and damping times corresponding to a particular neutrino production mechanism are evaluated. The obtained results imply that neutrino radiation, by more rapid damping of the nonradial oscillations of a newly formed neutron star in a supernova explosion, would hinder gravitational radiation, thus reducing the possibility of its detection.
Kazanas, D.↗
Approximation methods in gravitational-radiation theory
The observation of gravitational-radiation damping in the binary pulsar PSR 1913 + 16 and the ongoing experimental search for gravitational waves of extraterrestrial origin have made the theory of gravitational radiation an active branch of classical general relativity. In calculations of gravitational radiation, approximation methods play a crucial role. Recent developments are summarized in two areas in which approximations are important: (a) the quadrupole approxiamtion, which determines the energy flux and the radiation reaction forces in weak-field, slow-motion, source-within-the-near-zone systems such as the binary pulsar; and (b) the normal modes of oscillation of black holes, where the Wentzel-Kramers-Brillouin approximation gives accurate estimates of the complex frequencies of the modes.
Will, C. M.↗
Gravitational Radiation from Neutron Stars
Gravitational radiation from oscillating neutron stars
NEUTRON STAR↗
Gravitational radiation quadrupole formula is valid for gravitationally interacting systems
An argument is presented for the validity of the quadrupole formula for gravitational radiation energy loss in the far field of nearly Newtonian (e.g., binary stellar) systems. This argument differs from earlier ones in that it determines beforehand the formal accuracy of approximation required to describe gravitationally self-interacting systems, uses the corresponding approximate equation of motion explicitly, and evaluates the appropriate asymptotic quantities by matching along the correct space-time light cones.
Walker, M.↗
The generation of gravitational radiation by escaping supernova neutrinos
Formulae for the gravitational radiation due to the anisotropic axisymmetric emission of neutrinos from a small source are derived. We find that a burst of neutrinos released anisotropically from a supernova will generate a burst of gravitational radiation that may be comparable in amplitude and energy to the gravitational radiation generated by the fluid motion in the collapse of the supernova core.
Epstein, R.↗
Gravitational radiation from binary systems in alternative metric theories of gravity - Dipole radiation and the binary pulsar
The generation of gravitational radiation in several currently viable metric theories of gravitation (Brans-Dicke, Rosen, Ni, and Lightman-Lee) is analyzed, and it is shown that these theories predict the emission of dipole gravitational radiation from systems containing gravitationally bound objects. In the binary system PSR 1913 + 16, this radiation results in a secular change in the orbital period of the system with a nominal magnitude of 3 parts in 100,000 per year. The size of the effect is proportional to the reduced mass of the system, to the square of the difference in (self-gravitational energy)/(mass) between the two components of the system, and to a parameter, xi, whose value varies from theory to theory. In general relativity xi equals 0, in Rosen's (1973) theory xi equals -20/3, and in Ni's (1973) theory xi equals -400/3. The current upper limit on such a secular period change is one part in 1 million per year. It is shown that further observations of the binary system that tighten this limit and that establish the masses of the components and the identity of the companion may provide a crucial test of otherwise viable alternatives to general relativity.
Will, C. M.↗
Gravitational radiation from a solid-crust neutron star
The relationship between the rapid rotation of the millisecond pulsar and gravitational radiation is addressed. By balancing gravitational radiation against the rate of rotational energy loss, it is found that if the effective triaxiality exceeds about 10 to the -9th, gravitational radiation alone would spin a millisecond pulsar down at a faster rate than the observed period derivative. It is shown that the effective triaxiality is much less than the maximum triaxiality, so that gravitational radiation is not likely to play a major role in the evolution of millisecond pulsars even in the absence of damping. Damping times for precession of the solid crust are estimated to be less than 2000 years.
Alpar, M. A.↗
Modeling Gravitational Radiation Waveforms from Black Hole Mergers
Gravitational radiation from merging binary black hole systems is anticipated as a key source for gravitational wave observations. Ground-based instruments, such as the Laser Interferometer Gravitational-wave Observatory (LIGO) may observe mergers of stellar-scale black holes, while the space-based Laser Interferometer Space Antenna (LISA) observatory will be sensitive to mergers of massive galactic-center black holes over a broad range of mass scales. These cataclysmic events may emit an enormous amount of energy in a brief time. Gravitational waves from comparable mass mergers carry away a few percent of the system's mass-energy in just a few wave cycles, with peak gravitational wave luminosities on the order of 10^23 L_Sun. Optimal analysis and interpretation of merger observation data will depend on developing a detailed understanding, based on general relativistic modeling, of the radiation waveforms. We discuss recent progress in modeling radiation from equal mass mergers using numerical simulations of Einstein's gravitational field equations, known as numerical relativity. Our simulations utilize Adaptive Mesh Refinement (AMR) to allow high-resolution near the black holes while simultaneously keeping the outer boundary of the computational domain far from the black holes, and making it possible to read out gravitational radiation waveforms in the weak-field wave zone. We discuss the results from simulations beginning with the black holes orbiting near the system's innermost stable orbit, comparing the recent simulations with earlier "Lazarus" waveform estimates based on an approximate hybrid numerical/perturbative technique.
Baker, J. G.↗
Gravitational radiation and the ultimate speed in Rosen's bimetric theory of gravity
In Rosen's bimetric theory of gravity the (local) speed of gravitational radiation is determined by the combined effects of cosmological boundary values and nearby concentrations of matter. It is possible for the speed of gravitational radiation to be less than the speed of light. It is here shown that the emission of gravitational radiation prevents particles of nonzero rest mass from exceeding the speed of gravitational radiation. Observations of relativistic particles place limits on the speed of gravitational radiation and the cosmological boundary values today, and observations of synchroton radiation from compact radio sources place limits on the cosmological boundary values in the past.
Caves, C. M.↗
Gravitational radiation from neutron stars.
Calculation of gravitational radiation from pulsating and rotating objects according to weak field limit formula of general relativity and applied to neutron star data
GRAVITATIONAL RADIATION↗