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A. M. Gilbert, J. R. Graham (UC Berkeley)
Using high-resolution near-IR spectroscopy, we measure kinematic masses of super star clusters (SSCs) in the dwarf irregular galaxy NGC 1569, and use them to constrain the cluster initial mass functions (IMFs). Assuming that the clusters are virialized, we find masses of 2.3 x 105 M\sun for SSC B, 3.9 x 105 M\sun for SSC A1, and 4.4 x 105 Msun for SSC A2. Comparing the observed light-to-mass ratios with those calculated using population synthesis models reveals that these clusters are consistent with having IMFs extending from 100 M\sun down to 0.1 M\sun. The Wolf-Rayet-emitting component of the double cluster A, A2, has much more mass per unit light than A1 and B, and is more consistent with a Scalo or Kroupa IMF than a Salpeter IMF. Clusters A1 and B are better explained by a Salpeter IMF. There is no evidence for a truncated IMF in these clusters.
This work was funded in part by a NASA GSRP Fellowship.
The author(s) of this abstract have provided an email address for comments about the abstract: agilbert@astro.berkeley.edu