Evolution of circular, nonequatorial orbits of Kerr black holes due to gravitational-wave emission. II. Inspiral trajectories and gravitational waveforms - art. no. 064004

The inspiral of a "small" (mu similar to1-100M(circle dot)) compact body in to a "large" (M similar to 10(5-7) M-circle dot) black hole is a key source of gravitational radiation for the space-based gravitational-wave observat ory LISA. The waves from such inspirals will probe the extreme strong-field nature of the Kerr metric. In this paper, I investigate the properties of a restricted family of such inspirals (the inspiral of circular, inclined o rbits) with an eye toward understanding observable properties of the gravit ational waves that they generate. Using results previously presented to cal culate the effects of radiation reaction, I assemble the inspiral trajector ies (assuming that radiation reacts adiabatically, so that over short time scales the trajectory is approximately geodesic) and calculate the wave gen erated as the compact body spirals in. I do this analysis for several black hole spins, sampling a range that should be indicative of what spins we wi ll encounter in nature. The spin has a very strong impact on the waveform. In particular. when the hole rotates very rapidly, tidal coupling between t he inspiraling body and the event horizon has a very strong influence on th e inspiral time scale. which in turn has a big impact on the gravitational wave phasing. The gravitational waves themselves are very usefully describe d as 'multi-voice chirps": the wave is a sum of "voices," each correspondin g to a different harmonic of the fundamental orbital frequencies. Each voic e has a rather simple phase evolution. Searching for extreme mass ratio ins pirals voice-by-voice may be more effective than searching for the summed w aveform all at once.