2014AJ....147..150D

We have obtained radial velocity measurements for 51 new globular clusters around the Sombrero galaxy. These measurements were obtained using spectroscopic observations from the AAOmega spectrograph on the Anglo-Australian Telescope and the Hydra spectrograph at WIYN. Combining our own past measurements and velocity measurements obtained from the literature, we have constructed a large database of radial velocities that contains a total of 360 confirmed globular clusters. Previous studies' analyses of the kinematics and mass profile of the Sombrero globular cluster system have been constrained to the inner ∼9' (∼24 kpc or ∼5R_e), but our new measurements have increased the radial coverage of the data, allowing us to determine the kinematic properties of M104 out to ∼15' (∼41 kpc or ∼9R_e). We use our set of radial velocities to study the GC system kinematics and to determine the mass profile and V-band mass-to-light profile of the galaxy. We find that M/L_V increases from 4.5 at the center to a value of 20.9 at 41 kpc (∼9R_e or 15'), which implies that the dark matter halo extends to the edge of our available data set. We compare our mass profile at 20 kpc (∼4R_eor ∼7.'4) to the mass computed from X-ray data and find good agreement. We also use our data to look for rotation in the globular cluster system as a whole, as well as in the red and blue subpopulations. We find no evidence for significant rotation in any of these samples.