Contribution
The globular cluster system of NGC 5128: ages, metallicities, kinematics and structural properties
Presenter: Kristin Woodley (McMaster University)
Abstract: Globular clusters can probe the formation history of galaxies by providing evidence for the chemical evolution and major episodes of star formation in their host galaxies, by examining their kinematic signatures, as well as their structural parameters. Elliptical galaxies are particularly important as they can form from a variety of channels, including formation at early times, major mergers, and accretion of smaller galaxies. The giant elliptical NGC 5128 (Centaurus A), at a mere 4 Mpc away, gives us the only opportunity to study in extensive detail the globular cluster system of a recent merger galaxy. We have studied the globular cluster system of NGC 5128 in three ways: 1) using Gemini-S/GMOS low-resolution, high signal-to-noise spectroscopy of over 70 globular clusters, we have obtained ages and metallicities, as well as the level of alpha enrichment of the metal-poor and metal-rich globular cluster subpopulations, 2) with a large sample of confirmed globular clusters, we have explored the rotational signature and velocity dispersion of the galaxy's halo, as well as the dependence of these properties on galactocentric distance and globular cluster age and metallicity. We have also analyzed the dynamics, mass, and M / L ratio of the galaxy using the globular clusters as tracers, 3) lastly, we have measured the structural parameters, such as half-light radii and ellipticity, of the globular clusters from a superb 1.2 square degree Magellan/IMACS image taken in 0.5 arcsec seeing. We will present the findings of these studies and discuss the connection to the formation and evolution of NGC 5128.