Confusing binaries: the role of stellar binaries in biasing disk
  properties in the Galactic Center
  The population of young stars near the Supermassive black hole (SMBH) in the
Galactic Center (GC) has presented an unexpected challenge to theories of star
formation. Kinematics measurements of these stars have revealed a stellar disk
structure (with an apparent 20% disk membership) that has provided important
clues to the origin of these mysterious young stars. However many of the
apparent disk properties are difficult to explain, including the low disk
membership fraction and the high eccentricities, given the youth of this
population. Thus far, all efforts to derive the properties of this disk have
made the simplifying assumption that stars at the GC are single stars.
Nevertheless, stellar binaries are prevalent in our Galaxy, and recent
investigations suggested that they may also be abundant in the Galactic Center.
Here we show that binaries in the disk can largely alter the apparent orbital
properties of the disk. The motion of binary members around each other adds a
velocity component, which can be comparable to the magnitude of the velocity
around the SMBH in the GC. Thus neglecting the contribution of binaries can
significantly vary the inferred stars' orbital properties. While the disk
orientation is unaffected the apparent disk's 2D width is increased to about
11.2deg, similar to the observed width. For a population of stars orbiting the
SMBH with zero eccentricity, unaccounted for binaries will create a wide
apparent eccentricity distribution with an average of 0.23.This is consistent
with the observed average eccentricity of the stars' in the disk. We suggest
that this high eccentricity value, which poses a theoretical challenge, may be
an artifact of binary stars. Finally our results suggest that the actual disk
membership might be significantly higher than the one inferred by observations
that ignore the contribution of binaries, alleviating another theoretical
challenge.
