Constraints on the origins of hypervelocity stars: velocity
  distribution, mergers and star-formation history
  In recent years surveys have identified several dozen B stars in the Milky
Way halo moving faster than the local escape speed. The origin of most of these
hypervelocity stars (HVSs) is still poorly constrained. Here we show that the
velocity distribution, and in particular the deficiency in >700 km/s HVSs is
inconsistent with binary disruptions by the massive black hole (MBH) in the
Galactic Centre. This conclusion holds in the full and empty loss cone regime,
and for secular instabilities in eccentric disks. Accounting for multiple close
encounters between binaries and the MBH, does not qualitatively change the
results. Moreover, there is no observed counterpart population in the Galactic
Centre that is consistent with the HVSs. The star-formation history could be
tuned explain the HVS velocity distribution, but this tuning would produce a
mismatch with the observed HVS flight times. Frequent stellar collisions of the
binary components due to interactions with the MBH do not significantly impact
the velocity distribution in the Galactic halo. Such collisions, however, can
leave observable remnants in the Galactic Centre, and potentially explain the
origins of G2-like dust clouds.
