On the interpretation of the globular cluster luminosity function

Abstract

The conversion of the globular cluster luminosity function (GCLF; dN/d log L) to the globular cluster mass function (GCMF; dN/d log M) is addressed. Dissolving globular clusters (GCs) become preferentially depleted in low-mass stars which have a high mass-to-light ratio (M/L). This has been shown to result in an M/L that increases with GC luminosity or mass, because more massive GCs have lost a smaller fraction of their stars than low-mass GCs. Using GC models, we study the influence of the luminosity dependency of M/L on the inferred GCMF. The observed GCLF is consistent with a power law or Schechter-type GC initial mass function in combination with a cluster mass-dependent mass-loss rate. Below the peak, the logarithmic slope of the GCMF is shallower than that of the GCLF (0.7 versus 1.0), whereas the peak mass is 0.1-0.3 dex lower when accounting for the variability of M/L than in the case where a constant M/L is adopted. © 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A.