Modeling Kicks from the Merger of Generic Black-hole Binaries

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum “recoil kick” of up to ∼ 4000 km s. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick parallel to the orbital axis does not scale as ∼ η (where η is the symmetric mass ratio), as previously proposed, but is more consistent with ∼ η. We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters. Subject headings: black hole physics – galaxies: nuclei – gravitational waves — relativity