Effects of post-Newtonian Spin Alignment on the Distribution of
  Black-Hole Recoils
  Recent numerical relativity simulations have shown that the final black hole
produced in a binary merger can recoil with a velocity as large as 5,000 km/s.
Because of enhanced gravitational-wave emission in the so-called "hang-up"
configurations, this maximum recoil occurs when the black-hole spins are
partially aligned with the orbital angular momentum. We revisit our previous
statistical analysis of post-Newtonian evolutions of black-hole binaries in the
light of these new findings. We demonstrate that despite these new
configurations with enhanced recoil velocities, spin alignment during the
post-Newtonian stage of the inspiral will still significantly suppress (or
enhance) kick magnitudes when the initial spin of the more massive black hole
is more (or less) closely aligned with the orbital angular momentum than that
of the smaller hole. We present a preliminary study of how this post-Newtonian
spin alignment affects the ejection probabilities of supermassive black holes
from their host galaxies with astrophysically motivated mass ratio and initial
spin distributions. We find that spin alignment suppresses (enhances) ejection
probabilities by ~ 40% (20%) for an observationally motivated mass-dependent
galactic escape velocity, and by an even greater amount for a constant escape
velocity of 1,000 km/s. Kick suppression is thus at least a factor two more
efficient than enhancement.
