An Extremely Top-Heavy IMF in the Galactic Center Stellar Disks
  We present new observations of the nuclear star cluster in the central parsec
of the Galaxy with the adaptive optics assisted, integral field spectrograph
SINFONI on the ESO/VLT. Our work allows the spectroscopic detection of early
and late type stars to m_K >= 16, more than 2 magnitudes deeper than our
previous data sets. Our observations result in a total sample of 177 bona fide
early-type stars. We find that most of these Wolf Rayet (WR), O- and B- stars
reside in two strongly warped disks between 0.8" and 12" from SgrA*, as well as
a central compact concentration (the S-star cluster) centered on SgrA*. The
later type B stars (m_K>15) in the radial interval between 0.8" and 12" seem to
be in a more isotropic distribution outside the disks. The observed dearth of
late type stars in the central few arcseconds is puzzling, even when allowing
for stellar collisions. The stellar mass function of the disk stars is
extremely top heavy with a best fit power law of dN/dm ~ m^(-0.45+/-0.3). Since
at least the WR/O-stars were formed in situ in a single star formation event ~6
Myrs ago, this mass function probably reflects the initial mass function (IMF).
The mass functions of the S-stars inside 0.8" and of the early-type stars at
distances beyond 12" are compatible with a standard Salpeter/Kroupa IMF (best
fit power law of dN/dm ~ m^(-2.15+/-0.3)).
