Background giants in the field of the globular cluster M22: Kinematics of the galactic bulge

We report radial velocities, metallicities, and near-IR photometry for about 100 giants in the field of the globular cluster M22, at l,b=(9.9°,-7.6°). Most of them are bulge giants, non-members of the cluster from proper motions. Dividing the sample according to metallicity, we find that the giants more metal-poor than [Fe/H]≈-1 have halo-like kinematics, while the more metal-rich giants have higher rotation and smaller velocity dispersion, which we identify with the bulge. Such dependences of kinematics on metal abundance (which may be due to a mix of populations) are predicted by dissipational collapse models of formation for the inner Galaxy. The 11 M giants in the field follow bulge rather than halo kinematics.