S-stars in the Galactic center and hypervelocity stars in the Galactic
  halo: two faces of the tidal breakup of stellar binaries by the central
  massive black hole?
  In this paper, we investigate the link between the hypervelocity stars (HVSs)
discovered in the Galactic halo and the S-stars moving in the Galactic center
(GC), under the hypothesis that they are both the products of the tidal breakup
of the same population of stellar binaries by the central massive black hole
(MBH). By adopting several hypothetical models for binaries to be injected into
the vicinity of the MBH and doing numerical simulations, we realize the tidal
breakup processes of the binaries and their follow-up evolution. We find that
many statistical properties of the detected HVSs and S-stars can be reproduced
under some binary injecting models, and their number ratio can be reproduced if
the stellar initial mass function is top-heavy (e.g., with slope ~-1.6). The
total number of the captured companions is ~50 that have masses in the range
~3-7Msun and semimajor axes <~4000 AU and survive to the present within their
main-sequence lifetime. The innermost one is expected to have a semimajor axis
~300-1500 AU and a pericenter distance ~10-200 AU, with a significant
probability of being closer to the MBH than S2. Future detection of such a
closer star would offer an important test to general relativity. The majority
of the surviving ejected companions of the S-stars are expected to be located
at Galactocentric distances <~20 kpc, and have heliocentric radial velocities
~-500-1500 km/s and proper motions up to ~5-20 mas/yr. Future detection of
these HVSs may provide evidence for the tidal-breakup formation mechanism of
the S-stars.
