Astronomy and Astrophysics for the 1980's, Volume 2 Reports of the Panels (1983) / Chapter Skim
Currently Skimming:
X. Gravitational-Wave Astronomy
X. Gravitational-Wave Astronomy
Pages 90-97
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 90... ...
2. Harness Gravitational Waves for Observational Astronomy It is likely that gravitational waves will reveal properties of their sources that one can never learn by electromagnetic, cosmic-ray, or neutrino studies.
|
From page 91... ...
Among the phenomena that one might study by observing gravitational waves are the dynamics of the collapsing cores of supernovae; the dynamical evolution of newborn, rapidly rotating neutron stars; quakes in neutron stars; the dynamics of the formation of black holes by stellar collapse; collisions between compact objects such as black holes and neutron stars in the nuclei of distant galaxies; the internal structures of common-envelope binary stars; and white-dwarf oscillations produced by nova outbursts. In addition there may exist a stochastic background of gravitational waves, pregalactic or · .
|
From page 92... ...
Ground-Based Detectors By the beginning of the 1970's, investigators at the University of Maryland had constructed the world's first ground-based gravitational-wave detectors: 1-ton aluminum bars suspended in vacuum and instrumented with piezoelectric strain transducers. They observed coincident excitations of these detectors that they regarded as evidence either for a positive detection or for the presence of some unknown kind of "background." Between 1970 and 1975 a number of other laboratories constructed and operated detectors similar, but not identical, to those at Maryland.
|
From page 93... ...
The sole exception is the use of the Earth's quadrupole oscillations as a detector at specific resonant frequencies of 3.1 X 10 4 Hz, 6.8 X 10 4 Hz, 1.1 X 10 3 Hz, etc. Gravimetric monitoring of the 3.1 X 10-4 Hz mode has achieved a sensitivity, limited by seismic noise, corresponding to h near 2 X 10-14, which is sufficient to detect wave bursts of the maximum strength compatible with conventional theories.
|
From page 94... ...
5. Gravitational-Wave Theorv Progress in gravitational-wave theory during the 1970's included elucidation of how the search for gravitational waves can test theories of gravity, estimates of the characteristics of the waves emitted by astrophysical sources, and the development of new mathematical techniques for computing the forms of gravitational waves produced by various hypothetical sources.
|
From page 95... ...
Doppler tracking of spacecraft for the purpose of detecting gravitational waves is not currently being pursued outside the United States, except for European cooperation on the ISPM. Theoretical work outside the United States has concentrated on the mathematical theory of gravitational radiation.
|
From page 96... ...
Promising ideas have been put forward for bar detectors that would achieve such sensitivities but probably with responses confined to a narrow band inside the frequency range from 10 to 10 Hz. They might be able to detect cosmic signals but would probably miss most of the details of any waves except those from periodic sources.
|
From page 97... ...
Especially important is numerical solution of the Einstein field equations to determine the gravitational waveforms in(t) produced by astrophysical sources.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.