Star Clusters in M31: VII. Global Kinematics and Metallicity
  Subpopulations of the Globular Clusters
  We carry out a joint spatial-kinematical-metallicity analysis of globular
clusters (GCs) around the Andromeda Galaxy (M31), using a homogeneous,
high-quality spectroscopic dataset. In particular, we remove the contaminating
young clusters that have plagued many previous analyses. We find that the
clusters can be divided into three major metallicity groups based on their
radial distributions: (1) an inner metal-rich group ([Fe/H] > -0.4), (2) a
group with intermediate metallicity (with median [Fe/H]=-1), (3) and a
metal-poor group, with [Fe/H] < -1.5. The metal-rich group has kinematics and
spatial properties like the disk of M31, while the two more metal-poor groups
show mild prograde rotation overall, with larger dispersions - in contrast to
previous claims of stronger rotation. The metal-poor GCs are the least
concentrated group; such clusters occur five times less frequently in the
central bulge than do clusters of higher metallicity. Despite some well-known
differences between the M31 and Milky Way GC systems, our revised analysis
points to remarkable similarities in their chemodynamical properties, which
could help elucidate the different formation stages of galaxies and their GCs.
In particular, the M31 results motivate further exploration of a metal-rich GC
formation mode in situ, within high-redshift, clumpy galactic disks.
