Recent calculations of the recoil velocity in black-hole binary mergers have found kick velocities of ≈2500km/s for equal-mass binaries with anti-aligned initial spins in the orbital plane. In general the dynamics of spinning black holes can be extremely complicated and are difficult to analyze and understand. In contrast, the ``superkick'' configuration is an example with a high degree of symmetry that also exhibits exciting physics. We exploit the simplicity of this ``test case'' to study more closely the role of spin in black-hole recoil and find that: the recoil is with good accuracy proportional to the difference between the (l=2,m=±2) modes of Ψ4, the major contribution to the recoil occurs within 30M before and after the merger, and that this is after the time at which a standard post-Newtonian treatment breaks down. We also discuss consequences of the (l=2,m=±2) asymmetry in the gravitational wave signal for the angular dependence of the SNR and the mismatch of the gravitational wave signals corresponding to the north and south poles.
@article{arxiv.0707.0135,
title = {Exploring black hole superkicks},
author = {Bernd Bruegmann and Jose Gonzalez and Mark Hannam and Sascha Husa and Ulrich Sperhake},
journal= {arXiv preprint arXiv:0707.0135},
year = {2008}
}