We present a large sample of over 200 integrated-light spectra of confirmed globular clusters ( GCs ) associated with the Sombrero ( M104 ) galaxy taken with the DEIMOS instrument on the Keck telescope .
A significant fraction of the spectra have signal-to-noise levels high enough to allow measurements of GC metallicities using the method of Brodie & Huchra ( 1990 ) .
We find a distribution of spectroscopic metallicities ranging from –2.2 < [ Fe/H ] < +0.1 that is bimodal , with peaks at [ Fe/H ] \sim –1.4 and –0.6 .
Thus the GC system of the Sombrero galaxy , like a few other galaxies now studied in detail , reveals a bimodal spectroscopic metallicity distribution supporting the long-held belief that colour bimodality reflects two metallicity subpopulations .
This further suggests that the transformation from optical colour to metallicity for old stellar populations , such as GCs , is not strongly non-linear .
We also explore the radial and magnitude distribution with metallicity for GC subpopulations but small number statistics prevent any clear trends in these distributions .