The Kinematics and Dynamics of the Globular Clusters and Planetary Nebulae of NGC 5128
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abstract
A new kinematic and dynamic study of the halo of the giant elliptical galaxy,
NGC 5128, is presented. From a spectroscopically confirmed sample of 340
globular clusters and 780 planetary nebulae, the rotation amplitude, rotation
axis, velocity dispersion, and the total dynamical mass are determined for the
halo of NGC 5128. The globular cluster kinematics were searched for both radial
dependence and metallicity dependence by subdividing the globular cluster
sample into 158 metal-rich ([Fe/H] > -1.0) and 178 metal-poor ([Fe/H] < -1.0)
globular clusters. Our results show the kinematics of the metal-rich and
metal-poor subpopulations are quite similar. The kinematics are compared to the
planetary nebula population where differences are apparent in the outer regions
of the halo. The total mass of NGC 5128 is found using the Tracer Mass
estimator (Evans et al. 2003), to determine the mass supported by internal
random motions, and the spherical component of the Jeans equation to determine
the mass supported by rotation. We find a total mass of (1.0+/-0.2) x 10^(12)
Msun from the planetary nebulae data out to a projected radius of 90 kpc and
(1.3+/-0.5) x 10^(12) Msun from the globular clusters out to a projected radius
of 50 kpc. Lastly, we present a new and homogeneous catalog of known globular
clusters in NGC 5128. This catalog combines all previous definitive cluster
identifications from radial velocity studies and HST imaging studies, as well
as 80 new globular clusters from a study of M.A. Beasley et al. (2007, in
preparation).
