Mysterious Globular Cluster System of the Peculiar Massive Galaxy M85
  We present a study on stellar population and kinematics of globular clusters
(GCs) in the peculiar galaxy M85. We obtain optical spectra of 89 GCs at 8 kpc
$< R <$ 160 kpc using the MMT/Hectospec. We divide them into three groups,
blue/green/red GCs (B/G/RGCs), with their $(g-i)_0$ colors. All GC
subpopulations have mean ages of 10 Gyr, but showing differences in
metallicities. The BGCs and RGCs are the most metal-poor ([Z/H] $\sim -1.49$)
and metal-rich ([Z/H] $\sim -0.45$), respectively, and the GGCs are in between.
We find that the inner GC system exhibits a strong overall rotation that is
entirely due to a disk-like rotation of the RGC system. The BGC system shows
little rotation. The GGCs show kinematic properties clearly distinct among the
GC subpopulations, having higher mean velocities than the BGCs and RGCs and
being aligned along the major axis of M85. This implies that the GGCs have an
origin different from the other GC subpopulations. The rotation-corrected
velocity dispersion of the RGC system is much lower than that of the BGC
system, indicating the truncation of the red halo of M85. The BGCs have a flat
velocity dispersion profile out to $R$ = 67 kpc, reflecting the dark matter
extent of M85. Using the velocity dispersion of the BGC system, we estimate the
dynamical mass of M85 to be $3.8 \times 10^{12} M_{\odot}$. We infer that M85
has undergone merging events lately, resulting in the peculiar kinematics of
the GC system.
