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Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/203231
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- The assembly and chemical evolution of nearby early-type galaxies
- Foster, Caroline
- Despite the great successes of the current cosmological paradigm at explaining structure formation, especially on large scales, the details of the formation and evolution of structures such as galaxies is ill understood. In this Thesis, we address this important question of galaxy formation by probing the assembly and chemical evolution of nearby galaxies and their globular cluster systems. To this end, we obtain 144 near-infrared spectra of globular clusters around the giant elliptical galaxy NGC 1407 using DEIMOS. We develop a technique to obtain metallicities of extragalactic globular clusters from near-infrared integrated light spectra. We use the metallicity sensitive calcium ii triplet features around 8600 Å. These spectroscopic metallicities are then compared with those inferred from the integrated colours. Several discrepancies are found and we explore their possible origins and implications. We use a recently developed method to extract spatially resolved galaxy stellar light spectra from our DEIMOS observations for the three intermediate mass to massive early-type galaxies NGC 1407, NGC 2768 and NGC 4494. We use the calcium triplet to derive galaxy stellar light metallicities and obtain metallicity gradients out to unprecedentedly large galactocentric radii for galaxies of these masses. The derived metallicity gradient of NGC 1407 suggests that it is consistent with having formed from significant amounts of early dissipation, with little subsequent star-formation and major mergers. On the other hand, the metallicity gradient measured in NGC 2768 is consistent with a formation in a dissipational major merger event. The case of NGC 4494 is then explored in greater detail. While we are unable to measure a significant metallicity gradient for this galaxy, we explore its stellar kinematic and the metallicities and kinematics of its globular cluster system. We also use wide field imaging of the galaxy and globular clusters to inform our conclusions. We then combine these several observational lines of evidence and compare them to predictions from galaxy formation scenarios. In this manner, we are able to conclude that this galaxy is also consistent with a formation in a major merger. This Thesis shows the power of combined photometric and spectroscopic studies in constraining the formation and evolution of individual galaxies.
- Publication type
- Thesis (PhD)
- Research centre
- Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
- Publication year
- Australasian Digital Theses collection
- Copyright © 2011 Caroline Foster.