Towards a new understanding of star formation in galaxies
by
Pavel Kroupa(Argelander Institute for Astronomy (AIfA) University of Bonn)
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Europe/Stockholm
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Description
The stellar IMF is the distribution function of stellar masses born
together in one causally connected event within a spatial region of
not more than a few pc in extend. It cannot be measured in any system,
but statistical methods combined with corrections for dynamical bias
allows one to infer the existence of a universal canonical IMF as the
parent distribution from which the various simple stellar populations
are drawn. There is no evidence for variation of the IMF except at the
highest star-burst cluster masses above 106 Msun and in the immediate
vicinity of the Galactic super massive black hole. The IMF in a whole
galaxy is, in contrast, that of a composite population such that the
IMFs of the individual simple populations must be added. This leads to
an integral over the currently forming star cluster population and
implies the integrated galactic IMF (IGIMF) to be top light. The
steepness of the IGIMF for massive stars can be shown to depend on the
star formation rate of the galaxy. This leads to an entirely new
avenue of understanding galaxy evolution with potentially deep
insights into fundamental physics issues.
