Head-on collision of two equal mass black holes.

We present results from the first fully nonlinear numerical calculations of the head–on collision of two unequal mass black holes. Selected waveforms of the most dominant ` = 2, 3 and 4 quasinormal modes are shown, as are the total radiated energies and recoil velocities for a range of mass ratios and initial separations. Our results validate the close and distant separation limit perturbation studies, and suggest that the head–on collision scenario is not likely to produce an astrophysically significant recoil effect.