1212.3355 (Maryam Habibi et al.)

The Arches cluster out to its tidal radius: dynamical mass segregation and the effect of the extinction law on the stellar mass function    [PDF]

Maryam Habibi, Andrea Stolte, Wolfgang Brandner, Benjamin Hußmann, Kentaro Motohara

The Galactic Center is the most active site of star formation in the Milky Way Galaxy, where particularly high-mass stars have formed very recently and are still forming today. However, since we are looking at the Galactic Center through the galactic disk, knowledge of extinction is crucial to study the region. The Arches cluster is a young, massive starburst cluster, near the Galactic Center. We observed the Arches cluster out to its tidal radius using Ks band imaging obtained with NAOS/CONICA at the VLT combined with Subaro/Cisco J-band data to gain a full understanding of the cluster mass distribution. We show that the determination of the mass of the most massive star in the Arches cluster, which had been used in previous studies to establish an upper-mass limit for the star formation process in the Milky Way, strongly depends on the assumed slope of the extinction law. Assuming the two regimes of widely used infrared extinction laws we show that the difference can reach up to 30% in extracted initial mass and ~1 magnitude in acquired Ks-band extinction while the present mass function slope changes by ~ 0.17 dex. The present-day mass function slopes derived assuming the Nishiyama et al. (2009) extinction law are increasing from a flat slope of alpha_{Nishi}=-1.76 \pm 0.22 in the core (r<0.2 pc) to alpha_{Nishi}=-2.23 \pm 0.27 in the intermediate annulus 0.2 View original: http://arxiv.org/abs/1212.3355