The universality of the stellar initial mass function

Abstract

We propose that the stellar initial mass function (IMF) is universal in the sense that its functional form arises as a consequence of the statistics of random supersonic flows. A model is developed for the origin of the stellar IMF that contains a dependence on the average physical parameters (temperature, density and velocity dispersion) of the large-scale site of star formation. The model is based on recent numerical experiments of highly supersonic random flows that have a strong observational counterpart. It is shown that a Miller-Scalo-like IMF is naturally produced by the model for the typical physical conditions in molecular clouds. A more ‘massive’ IMF in star- bursts is also predicted.