Gravitational wave detection

For gravitational-wave detection [4.25], a MI with side arms of about 1-km length has been built where the optical path difference can be increased to A.y > 100 km by using highly reflective spherical mirrors and an ultrastable solid-state laser with a coherence length of A cAjy (see Sect. 14.8) [4.26]. 

For gravitational-wave detection [4.22] a M.I. with side arms of about 1 km length is being built where the optical path difference can be in-... 

Abstract This is an introduction to gravitational wave astronomy. The physical bases of gravitation and the generation and detection of gravitational waves are recalled and then kilometric detectors under construction are described. 

Black holes. One great achievement of gravitational wave astronomy would be the first detection of a signal coming directly from a black hole. Just like with neutron stars, black holes can emit gw either alone or in binary systems. 

Coalescence of black holes. The coalescence of two black holes will generate even more gravitational waves than neutron stars coalescence, and coalescence of two lOM black holes will be detectable up to 500 Mpc... 

The purpose of this experiment was to select the best thermal link to cool down sensitive masses of the order of 100-1000 kg for the detection of rare decays [24] and gravitational waves [25],... 

This is an extremely small quantity, which combined with the also extremely small interaction of gravitational waves (GWs) with matter makes it impossible to generate and detect GW on earth. Fast conversions of solar-size masses are required to produce signals with amplitudes that could be detectable. Astrophysical sources are for instance supernova explosions or a collision of two neutron stars or black holes. 

D.G. Blair The Detection of Gravitational Waves, Cambridge University Press, Cambridge (1991)... 

SQUIDs have been used in a large number of experiments where the detection of small magnetic fields is crucial. Some interesting cases include the study of magnetic fields from human brains associated with mental disorders (Barth et ai, 1984), the detection of gravitational waves (Clarke, 1986), and fluctuations in the earth s magnetic field related to geothermal effects (Clarke, 1983), etc. 

The basic part of such a detector (Fig. 14.68) is a Michelson interferometer with long arms (several kilometers) and an extremely well stabilized laser. If a gravitational wave causes a length difference AL between the two arms of the interferometer, a phase difference A0 = (47t/A,) AL appears between the two partial waves at the exit of the interferometer. The minimum detectable phase change A0 is limited by the phase noise If laser delivers N photons hv per second, the two detectors measure the intensities... 

Stochastic gravitational waves from the early universe. Can be detected as anisotropies of the Cosmic Microwave Background Radiation (CMBR). Waves from the big bang may be parametrically amplified by inflation. 

Since interferometers have broadband sensitivity, one can monitor the phase evolution of a gravitational wave over many cycles. This provides a method of discriminating the signal from noise, and increases the detectability of a gravitational wave signal. 

Optimal sensitivity to gravitational wave bursts in bar detectors. A burst is detected by searching for excess power deposited in the bar by the impulsive burst within the sensitive band of the bar. 

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