Gravitational wave astronomy: in anticipation of first sources to be detected

The first generation of long-baseline laser interferometric detectors of gravitational waves will start collecting data in 2001 - 2003. We carefully analyse their planned performance and compare it with the expected strengths of astrophysical sources. The scientific importance of the anticipated discovery of various gravitational wave signals and the reliability of theoretical predictions are taken into account in our analysis. We try to be conservative in evaluating both the theoretical uncertainties in the parameters of the source and the prospects of its detection. Upon considering many possible sources, we place our emphasis on (i) inspiraling binaries consisting of stellar mass black holes and (ii) relic gravitational waves. We conclude that inspiraling binary black holes are likely to be detected by the early ground-based interferometers first. We estimate that the first interferometers will see 2 - 3 events per year from black hole binaries with component masses of 10-15M(circle dot), with a signal-to-noise ratio of about 3, in a network of detectors consisting of GEO, VIRGO and two LIGOs. It appears that other possible sources, including coalescing neutron stars, are unlikely to be detected by the early instruments. We also argue that relic gravitational waves may be discovered by space-based interferometers in the frequency interval 2 x 10(-3) - 10(-2) Hz, at a signal-to-noise ratio level of about 3.