Spectral Energy Distribution Fitting of Globular Clusters in NGC 4874: Masses and Metallicities

Abstract In most nearby galaxies, photometry of the integrated light of their globular clusters (GCs) has been obtained in only two filters, yielding just a single color index. However, NGC 4874, the brightest central galaxy in the Coma Cluster, now has Hubble Space Telescope photometry available in 10 filters, giving us a special opportunity to test spectral energy distribution (SED) fitting procedures on GCs in distant galaxies. We fitted 29 of the brightest GCs with a library of SEDs from E-MILES and calculated the best-fit metallicity and mass of each cluster. Using the fitted masses and luminosities derived from the reddest magnitudes, in the flat portion of the GC spectrum, we also calculated inferred mass-to-light ratios for our sample GCs; these were in the range (M/L) ≃ 2–4, slightly larger than the average values for Milky Way GCs but within the conventional range.