POSSIBLE SUBGROUPS OF GLOBULAR CLUSTERS AND PLANETARY NEBULAE IN NGC 5128
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We use recently compiled position and velocity data for the globular cluster
and planetary nebula subsystems in NGC 5128, the nearby giant elliptical, to
search for evidence of past dwarf-satellite accretion events. Beyond a 10
arcmin (~11 kpc) radius in galactocentric distance, we find tentative evidence
for 4 subgroups of globular clusters and 4 subgroups of planetary nebulae.
These each have > 4 members within a search radius of 2 arcmin and internal
velocity dispersion of < 40 km/s, typical parameters for a dwarf galaxy. In
addition, 2 of the globular cluster groupings overlap with 2 of the planetary
nebulae groupings, and 2 subgroupings also appear to overlap with previously
known arc and shell features in the halo light. Simulation tests of our
procedure indicate that the probability of finding false groups due to chance
is < 1%.
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