Substructure in the Globular Cluster Populations of the Virgo Cluster
  Elliptical Galaxies M84 and M86
  We have carried out a search for substructure within the globular cluster
systems of M84 (NGC 4374) and M86 (NGC 4406), two giant elliptical galaxies in
the Virgo Cluster. We use wide-field (36 arcmin x 36 arcmin), multi-color
broadband imaging to identify globular cluster candidates in these two galaxies
as well as several other nearby lower-mass galaxies. Our analysis of the
spatial locations of the globular cluster candidates reveals several
substructures, including: a peak in the projected number density of globular
clusters in M86 that is offset from the system center and may be at least
partly due to the presence of the dwarf elliptical galaxy NGC 4406B; a bridge
that connects the M84 and M86 globular cluster systems; and a boxy iso-density
contour along the southeast side of the M86 globular cluster system. We divide
our sample into red (metal-rich) and blue (metal-poor) globular cluster
candidates to look for differences in the spatial distributions of the two
populations and find that the blue cluster candidates are the dominant
population in each of the substructures we identify. We also incorporate the
measurements from two radial velocity surveys of the globular clusters in the
region and find that the bridge substructure is populated by globular clusters
with a mix of velocities that are consistent with either M86 and M84, possibly
providing further evidence for interaction signatures between the two galaxies.
