SCYON Abstract

Received on February 27 2007

The Arches Cluster Mass Function

AuthorsSungsoo S. Kim (1), Donald F. Figer (2), Rolf P. Kudritzki (3), and F. Najarro (4)
Affiliation
(1) Kyung Hee University, Korea
(2) Rochester Institute of Technology, USA
(3) University of Hawaii, USA
(4) Consejo Superior de Investigaciones Cientificas, Spain
Accepted byAstrophysical Journal
Contact
URLhttp://www.arxiv.org/abs/astro-ph/0611377
Links

Abstract

We have analyzed H and Ks-band images of the Arches cluster obtained using the NIRC2 instrument on Keck with the laser guide star adaptive optics (LGS AO) system. With the help of the LGS AO system, we were able to obtain the deepest ever photometry for this cluster and its neighborhood, and derive the background-subtracted present-day mass function (PDMF) down to 1.3 Msun for the 5"-9" annulus of the cluster. We find that the previously reported turnover at 6 Msun is simply due to a local bump in the mass function (MF), and that the MF continues to increase down to our 50% completeness limit (1.3 Msun) with a power-law exponent of Gamma = -0.91 for the mass range of 1.3 < M/Msun < 50. Our numerical calculations for the evolution of the Arches cluster show that the Gamma values for our annulus increase by 0.1-0.2 during the lifetime of the cluster, and thus suggest that the Arches cluster initially had Gamma of -1.0 ~ -1.1, which is only slightly shallower than the Salpeter value.