Stellar Content of the Galactic Starburst Template NGC 3603 from Adaptive Optics Observations

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Abstract
We present near-infrared adaptive optics imaging of the Galactic starburst template NGC 3603 and its stellar center HD 97950. There is clear evidence for the presence of stars down to 1 or less. No cutoff or turnover in the initial mass function is evident. Applying theoretical models of the pre-main-sequence evolution of intermediate-mass stars to the observed color-color diagram, the color-magnitude diagram, and the luminosity function, we constrain both the age distribution and the initial mass function. Within the systematic errors, this initial mass function follows a Salpeter power law with index Γ ≤ -0.73 down to the observational limit of less than 1 . The stars with less than 4 appear to be younger than 106 yr, in contrast to previous age determinations of the high-mass content of HD 97950.