The Halos of Post-Merger Galaxies: A Detailed Study of NGC 5128 (Centaurus A)

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

AST 0098566 Ford Elliptical galaxies contain a large fraction of the stars and dark matter in the local universe, yet their formation mechanisms are still largely unknown. Understanding the formation and evolution of elliptical galaxies is essential for understanding galaxy formation, and, ultimately, the star formation history of the universe. In addition, ellipticals are often found to be the hosts of powerful active galactic nuclei (AGN) and understanding their evolution may also shed some light on the AGN phenomenon. Various competing scenarios of elliptical formation have been studied over the past decade. These include: 1) multiple bursts of early star formation, 2) merging of gas-rich spiral galaxies, and 3) prolonged accretion and tidal stripping of gas-poor galaxies. This project involves a detailed study of NGC 5128 (Centaurus A), the nearest giant elliptical galaxy. Cen A has undergone a recent merger with a gas-rich system, and is one of the prototypical classes of radio galaxies. This makes it an excellent laboratory in which to study both the fossil record of old stars in the halos of ellipticals, and the transitional states that result from mergers and nuclear activity. The present work will cover Cen A's halo as far out as a radius of 100 kpc. It will use broadband UBVRI and [O III] imaging and multifiber spectroscopy to constrain the origins of the stellar populations in Cen A. In particular it seeks to: 1. determine the origin of the faint halo light, i.e. the extended stellar disk, shells, and other possible merger remnants like accreted dwarf galaxies. 2. determine the spatial distribution, metallicity distribution, and kinematics of the globular cluster system. 3. determine the quantity, spatial extent, and timescale of AGN-induced star formation in the halo. 4. measure the extent of the elliptical galaxy halo, and quantify the total mass of its luminous and dark matter out to 100 kpc. ***