Investigating stellar-mass black hole kicks
  We investigate whether stellar-mass black holes have to receive natal kicks
in order to explain the observed distribution of low-mass X-ray binaries
containing black holes within our Galaxy. Such binaries are the product of
binary evolution, where the massive primary has exploded forming a stellar-mass
black hole, probably after a common envelope phase where the system contracted
down to separations of order 10-30 Rsun. We perform population synthesis
calculations of these binaries, applying both kicks due to supernova mass-loss
and natal kicks to the newly-formed black hole. We then integrate the
trajectories of the binary systems within the Galactic potential. We find that
natal kicks are in fact necessary to reach the large distances above the
Galactic plane achieved by some binaries. Further, we find that the
distribution of natal kicks would seem to be similar to that of neutron stars,
rather than one where the kick velocities are reduced by the ratio of black
hole to neutron-star mass (i.e. where the kicks have the same momentum). This
result is somewhat surprising; in many pictures of stellar-mass black-hole
formation, one might have expected black holes to receive kicks having the same
momentum (rather than the same speed) as those given to neutron stars.
