Origin of rotational kinematics in the globular cluster system of M31: A
  new clue to the bulge formation
  We propose that the rotational kinematics of the globular cluster system
(GCS) in M31 can result from a past major merger event that could have formed
its bulge component. We numerically investigate kinematical properties of
globular clusters (GCs) in remnants of galaxy mergers between two disks with
GCs in both their disk and halo components. We find that the GCS formed during
major merging can show strongly rotational kinematics with the maximum
rotational velocities of 140 - 170 km/s for a certain range of orbital
parameters of merging. We also find that a rotating stellar bar, which can be
morphologically identified as a boxy bulge if seen edge-on, can be formed in
models for which the GCSs show strongly rotational kinematics. We thus suggest
that the observed rotational kinematics of GCs with different metallicities in
M31 can be closely associated with the ancient major merger event. We discuss
whether the formation of the rotating bulge/bar in M31 can be due to the
ancient merger.
