  Hypervelocity stars (HVSs) are a natural consequence of the presence of a
massive nuclear black hole (Sgr A*) in the Galactic Center. Here we use the
Brown et al. sample of unbound and bound HVSs together with numerical
simulations of the propagation of HVSs in the Milky Way halo to constrain three
plausible ejection mechanisms: 1) the scattering of stars bound to Sgr A* by an
inspiraling intermediate-mass black hole (IMBH); 2) the disruption of stellar
binaries in the tidal field of Sgr A*; and 3) the two-body scattering of stars
off a cluster of stellar-mass black holes orbiting Sgr A*. We compare the
predicted radial and velocity distributions of HVSs with the limited-statistics
dataset currently available, and show that the IMBH model appears to produce a
spectrum of ejection velocities that is too flat. Future astrometric and deep
wide-field surveys of HVSs should shed unambiguous light on the stellar
ejection mechanism and probe the Milky Way potential on scales as large as 200
kpc.
