Schedule Jan 17, 2009
The Early Evolution of the Star Cluster Mass Function
Mark Gieles (ESO)

Recent studies have shown that the star cluster initial mass function (CIMF) can be well approximated by a power law, with indications for a steepening or truncation at high masses. This contribution considers the evolution of a Schechter type CIMF due to cluster disruption, with emphasis on the part of the mass function that is observable in the first ~1 Gyr. Cluster disruption due to the tidal field of the host galaxy and encounters with giant molecular clouds flattens the low-mass end of the mass function, but there is always a part of the `evolved Schechter function' that can be approximated by a power law with index -2. The mass range for which this holds shifts to higher masses with increasing age. Mean cluster masses derived from luminosity limited samples increase with age very similarly (due to the evolutionary fading of clusters). Empirical mass functions are, therefore, approximately power laws with index -2, or slightly steeper, at all ages. The results are illustrated by an application to the star cluster population of the interacting galaxy M51.

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