Kinematics and metallicities of globular clusters in M104

We have obtained spectra for globular cluster candidates in M104 with LDSS-2 on the William Herschel Telescope, confirming 34 objects as M104 globular clusters.We find a cluster velocity dispersion of ∼ 260 km/sec, and the Projected Mass Estimator gives a mass of 5.0 (3.5,6.7)× 10 11 M ⊙ for M104 within a projected radius of ∼ 330 ′′ (14 kpc for D=8.55 Mpc).Our best estimate for the mass-to-light ratio is M/L VT = 16 +5.5 -5.0 within the same radius.Considering all of the possible sources of uncertainty, we find a lower limit of M/L V = 5.3, which is larger than the M/L V found from rotation curve analyses inside 180 ′′ .We thus conclude that the mass-to-light ratio increases with radius, or in other words that M104 possesses a dark matter halo.There is a marginal detection of rotation in the M104 cluster system at the 92.5% confidence level; larger samples will be needed to investigate this possibility.Interestingly, the M104 globular cluster and planetary nebulae (PNe) kinematics are roughly consistent inside ∼ 100 ′′ .Finally, we find a mean cluster metallicity of [Fe/H] = -0.70 ± 0.3, which is more typical of clusters in gE/cD galaxies than it is of clusters in other spirals.