On the Interpretation of the Globular Cluster Luminosity Function

The conversion of the globular cluster luminosity function (GCLF, dN/d logL) to the globular cluster mass function (GCMF, dN/d logM) is addressed. Dissolving globular clusters (GCs) become preferentially depleted in low-mass stars, which have a high mass-to-light ratio. This has been shown to result in a mass-to-light ratio (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 powerlaw 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. Subject headings: Galaxy: kinematics and dynamics — (Galaxy:) globular clusters: general — galaxies: kinematics and dynamics — galaxies: star clusters — stellar dynamics