The Centaurus Group and the Outer Halo of NGC 5128: Are they Dynamically Connected?

Abstract

NGC 5128, a giant elliptical galaxy only $\sim 4$ Mpc away, is the dominant member of a galaxy group of over 80 probable members. The Centaurus group provides an excellent sample for a kinematic comparison between the halo of NGC 5128 and its surrounding satellite galaxies. A new study, presented here, shows no kinematic difference in rotation amplitude, rotation axis, and velocity dispersion between the halo of NGC 5128, determined from over $\sim 340$ of its globular clusters, and those of the Centaurus group as a whole. These results suggest NGC 5128 could be behaving in part as the inner component to the galaxy group, and could have begun as a large initial seed galaxy, gradually built up by minor mergers and satellite accretions, consistent with simple cold dark matter models. The mass and mass-to-light ratios in the B-band, corrected for projection effects, are determined to be $(1.3\pm 0.5)\times 10^{12}$ M$_{\sun}$ and $52\pm 22$ M$_{\sun}$/L$_{\sun}$ for NGC 5128 out to a galactocentric radius of 45 kpc, and $(9.2\pm 3.0)\times 10^{12}$ M$_{\sun}$ and $153\pm 50$ M$_{\sun}$/L$_{\sun}$ for the Centaurus group, consistent with previous studies.

14 pages, 3 tables, 7 figures, Accepted for publication in AJ

References in corpus (2)

• Eridanus - A Supergroup in the Local Universe?
• The Effect of Substructure on Mass Estimates of Galaxies

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• The Kinematics and Dynamics of the Globular Clusters and the Planetary Nebulae of NGC 5128
• Symphony: Cosmological Zoom-in Simulation Suites over Four Decades of Host Halo Mass
• Metal-poor nuclear star clusters in two dwarf galaxies near Centaurus A suggesting formation from the in-spiraling of globular clusters
• Tracing the outer halo in a giant elliptical to 25 Reff
• A Recent Major Merger Tale for the Closest Giant Elliptical Galaxy Centaurus A
• CANGAROO-III Search for Gamma Rays from Centaurus A and the $\omega$ Centauri Region
• Probing the Intermediate-Age Globular Clusters in NGC 5128 from Ultraviolet Observations
• Improved Lemaitre-Tolman model and the mass and turn-around radius in group of galaxies
• The Metallicity Distribution Function in Outer Halo Fields of Simulated Elliptical Galaxies Compared to Observations of NGC 5128
• The Cen A galaxy group: dynamical mass and missing baryons