Tidal break-up of binary stars at the Galactic center and its
  consequences
  The tidal breakup of binary star systems by the supermassive black hole
(SMBH) in the center of the galaxy has been suggested as the source of both the
observed sample of hypervelocity stars (HVSs) in the halo of the Galaxy and the
S-stars that remain in tight orbits around Sgr A*. Here, we use a
post-Newtonian N-body code to study the dynamics of main-sequence binaries on
highly elliptical bound orbits whose periapses lie close to the SMBH,
determining the properties of ejected and bound stars as well as collision
products. Unlike previous studies, we follow binaries that remain bound for
several revolutions around the SMBH, finding that in the case of relatively
large periapses and highly inclined binaries the Kozai resonance can lead to
large periodic oscillations in the internal binary eccentricity and
inclination. Collisions and mergers of the binary elements are found to
increase significantly for multiple orbits around the SMBH, while HVSs are
primarily produced during a binary's first passage. This process can lead to
stellar coalescence and eventually serve as an important source of young stars
at the galactic center.
