Tidal radii of globular clusters and the mass of the Milky Way

Tidal radii of remote globular clusters (RGC≥ 35 kpc) are used to provide constraints on the mass profile of the Milky Way galaxy that are independent of kinematic data. The available data are consistent with the profile of an isothermal sphere with circular velocity Vc= 220 ± 40 km s−1 in the radial range 35 ≤RGC≤ 100 kpc, in good agreement with all recent estimates. The more robust constraint at large distances from the Galactic Centre is provided by NGC 2419, yelding an enclosed mass of 1.3+2.9−1.0× 1012 M⊙ at RGC≃ 90 kpc.