Friday, June 7, 2013

1306.1229 (Carsten Weidner et al.)

The mmax-Mecl relation, the IMF and IGIMF: probabilistically sampled functions?    [PDF]

Carsten Weidner, Pavel Kroupa, Jan Pflamm-Altenburg
We introduce a new method to measure the dispersion of mmax values of star clusters and show that the observed sample of mmax is inconsistent with random sampling from an universal stellar initial mass function (IMF) at a 99.9% confidence level. The scatter seen in the mmax-Mecl data can be mainly (76%) understood as being the result of observational uncertainties only, while only a minority (42%) of the clusters agree with the expectations from random sampling. Additionally, new data on the local star-formation regions Taurus-Auriga and L1641 in Orion seem to make stochastically formed stellar populations rather unlikely. The data are however consistent with the local IGIMF (integrated galactic stellar initial mass function) theory according to which a stellar population is a sum of individual star-forming events each of which is described by well defined physical laws. Randomly sampled IMFs and henceforth scale-free star formation seems to be in contradiction to observed reality.
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