| Abstract | We have formulated a model to represent globular cluster luminosity functions (GCLFs) in distant galaxies by means of maximum-likelihood statistics. This model simultaneously accounts for the presence of a contaminating background population, incompleteness at faint magnitudes, and photometric measurement error. We apply this model to observational data sets for the three Virgo giant elliptical galaxies NGC 4365,4472, and 4649, to derive accurate new values for the GCLF peak and dispersion. With a Virgo core distance modulus of (m -M)_V_= 30.95+/-0.25, we obtain GCLF turnover luminosities for the three gEs as follows: M^0^_V_ = -7.12+/-0.36 and σ_t_ = 1.52+/-0.13 (NGC 4365), M^0^_V_ = -7.03+/-0.27 and σ_t_ = 1.30+/-0.07 (NGC 4472), and M^0^_V_ = -7.18+/-0.27 and σ_t_ = 1.15+/-0.07 (NGC 4649). Accordingly, the unweighted average of these GCLF parameter estimates are = - 7.11+/-0.3 and <σ_t_> = 1.32+/-0.09. Comparing with similar maximum-likelihood parameter estimates for M 31 and the Milky Way, we obtain mean differences {DELTA}M^0^_V_ = -0.31+/-0.33 mag and {DELTA}σ_t_ = -0.36+/-0.13 mag, in the sense that the GCLFs in the giant ellipticals are slightly less luminous at the turnover but with significantly large functional dispersion. |
