Globular Clusters in Dwarf Galaxies

Data are currently available on the luminosities and half-light radii of 101 globular clusters associated with low-luminosity parent galaxies. The luminosity distribution of globular clusters embedded in dwarf galaxies having M_v > -16 is found to differ dramatically from that for globular clusters surrounding giant host galaxies with M_v < -16. The luminosity distribution of globular clusters in giant galaxies peaks at M_v ∼ -7.5, whereas that for dwarf galaxies is found to increase monotonically down to the completeness limit of the cluster data at M_v ∼ -5.0. Unexpectedly, the power-law distribution of the luminosities of globular clusters hosted by dwarf galaxies is seen to be much flatter than that of the bright, unevolved part of the luminosity distribution of globular clusters associated with giant galaxies. The specific frequency of globular clusters fainter than M_v = -7.5 is found to be particularly high in dwarf galaxies. The luminosity distribution of the LMC globular clusters is similar to that found in giant galaxies and differs from those of globular clusters in dwarf galaxies. The present data appear to show no strong dependence of globular cluster luminosity on the morphological type of their parent galaxies. No attempt is made to explain the unexpected discovery that the luminosity distribution of globular clusters is critically dependent on parent galaxy luminosity (or mass) but insensitive to the morphological type of the host galaxy.