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Article Dans Une Revue The Astrophysical Journal Année : 2010

An Extremely Top-Heavy Initial Mass Function in the Galactic Center Stellar Disks

Y. Levin
  • Fonction : Auteur
M. Zilka
  • Fonction : Auteur

Résumé

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 mK >= 16, more than 2 mag 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 0farcs8 and 12'' from Sgr A*, as well as a central compact concentration (the S-star cluster) centered on Sgr A*. The later type B-stars (mK >15) in the radial interval between 0farcs8 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 vprop m -0.45± 0.3. WR/O-stars were formed in situ in a single star formation event ~6 Myr ago, this mass function probably reflects the initial mass function (IMF). The mass functions of the S-stars inside 0farcs8 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 vprop m -2.15± 0.3).

Dates et versions

hal-03730858 , version 1 (20-07-2022)

Identifiants

Citer

H. Bartko, Fabrice Martins, S. Trippe, T. K. Fritz, Reinhard Genzel, et al.. An Extremely Top-Heavy Initial Mass Function in the Galactic Center Stellar Disks. The Astrophysical Journal, 2010, 708, pp.834-840. ⟨10.1088/0004-637X/708/1/834⟩. ⟨hal-03730858⟩
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