Gravitational waves from a compact star in a circular, inspiral orbit, in the equatorial plane of a massive, spinning black hole, as observed by LISA

Results are presented from high-precision computations of the orbital evolution and emitted gravitational waves for a stellar-mass object spiraling into a massive black hole in a slowly shrinking, circular, equatorial orbit. The focus of these computations is inspiral near the innermost stable circular orbit (isco) ---more particularly, on orbits for which the angular velocity is 0. 03/₈ₒ₂₎10 at r₀=1 Gpc during the last year of inspiral. The hole's spin a has a factor of 10 influence on the range of M (at fixed) for which S/N>10, and the presence or absence of a white-dwarf--binary background has a factor of 3 influence. A comparison with predicted event rates shows strong promise for detecting these waves, but not beyond about 1 Gpc if the inspiraling object is a white dwarf or neutron star. This argues for a modest lowering of LISA's noise floor. A brief discussion is given of the prospects for extracting information from the observed waves.