An Overview of Gravitational-Wave Sources

Major relativity conferences such as GR16 traditionally include an overview talk on gravitational wave (GW) sources. Some excellent recent ones include those by Flanagan , Finn , and Bender et al. . Such talks are always by theorists, and can be described as basically informed speculation, since until now detectors sufficiently sensitive to detect GW’s have not existed. But km-scale laser interferometers (IFO’s) are now coming on-line, and it seems very likely these will detect mergers of compact binaries within the next seven years, and possibly much sooner. There are several other classes of sources that the ground-based IFO’s might well detect: massive star collapse (supernovae and hypernovae), rapidly rotating neutron stars, and possibly a GW stochastic background created in the early universe. A space-based interferometer, LISA, is also planned (though not yet fully funded), and could fly in ∼ 2011. There is one type of source — short-period galactic binaries — that LISA is guaranteed to observe (at its planned sensitivity), plus a list of very promising candidates: the inspiral and merger of supermassive black holes (SMBH’s), the inspiral and capture of compact objects by SMBH’s, and sources in the very early universe. In this article we review the various GW sources that have been studied, for both ground and space-based detectors, summarizing the best available