Self-organized criticality and the IMF of starbursts

Starburst clusters are perhaps the only objects where the initial mass function (IMF) of massive stars can be determined free from stochastic fluctuations due to small number statistics. We use new observations of the starburst cluster in 30 Doradus to support the conclusion that the massive star IMF is a universal power-law of slope very close to the Salpeter exponent Gamma = -1.35, Following Elmegreen, we extend and generalize models of random sampling of fractal clouds that predict the IMF to be a universal power law. The agreement between this prediction and the observations strongly suggests that the IMF of large clusters and associations is independent of local processes governing star formation.