The SLUGGS Survey: Globular cluster system kinematics and substructure
  in NGC 4365
  We present a kinematic analysis of the globular cluster (GC) system of the
giant elliptical galaxy NGC 4365 and find several distinct kinematic
substructures. This analysis is carried out using radial velocities for 269
GCs, obtained with the DEIMOS instrument on the Keck II telescope as part of
the SAGES Legacy Unifying Globulars and Galaxies Survey (SLUGGS). We find that
each of the three (formerly identified) GC colour subpopulations reveal
distinct rotation properties. The rotation of the green GC subpopulation is
consistent with the bulk of NGC 4365's stellar light, which `rolls' about the
photometric major axis. The blue and red GC subpopulations show `normal'
rotation about the minor axis. We also find that the red GC subpopulation is
rotationally dominated beyond 2.5 arcmin (~17 kpc) and that the root mean
squared velocity of the green subpopulation declines sharply with radius
suggesting a possible bias towards radial orbits relative to the other GC
subpopulations. Additionally, we find a population of low velocity GCs that
form a linear structure running from the SW to the NE across NGC 4365 which
aligns with the recently reported stellar stream towards NGC 4342. These low
velocity GCs have g'-i' colours consistent with the overall NGC 4365 GC system
but have velocities consistent with the systemic velocity of NGC 4342. We
discuss the possible formation scenarios for the three GC subpopulations as
well as the possible origin of the low velocity GC population.
