Dissertation/Thesis Abstract

A magnified view of high redshift star formation
by Wuyts, Eva, Ph.D., The University of Chicago, 2012, 149; 3526999
Abstract (Summary)

This work takes advantage of the magnified view of the z = 1−3 Universe provided by cluster-scale strong gravitational lensing to advance our understanding of the physical mechanisms driving the assembly of galaxies at this epoch of peak star formation. In the first chapter, high signal-to-noise multi-wavelength photometry and long-slit rest-frame optical spectroscopy for four of the brightest lensed galaxies known at z = 1−3 is combined for a detailed study of their stellar populations and the physical conditions of their ionized gas. I find these systems to be young starbursts without much dust content which have only recently started the build-up of their stellar mass. A comparison of SFR indicators from the dust-corrected UV light, the Hα and [O II] 3727 nebular emission lines, and the dust-reprocessed 24 µm emission suggests that the Calzetti dust extinction law is too flat to accurately correct dust extinction in young star-forming galaxies at z ∼ 2. In a second chapter, the observed relation between stellar mass and gas-phase metallicity for star-forming galaxies at z ∼ 2 is extended to lower stellar masses than previously studied, with a sample of 10 lensed galaxies. I find less redshift evolution of the mass-metallicity relation in this mass range. There is a general agreement with the local fundamental relation between metallicity, stellar mass and SFR from Mannucci et al., though the scatter becomes large for specific star formation rates > 10−9 yr−1 . Using the Kennicutt-Schmidt law to infer gas fractions, I investigate the importance of gas inflows and outflows on the shape of the mass-metallicity relation with simple analytical models. The last chapter presents a combined analysis of HST/WFC3 optical/near-IR imaging and Keck/OSIRIS near-IR IFU spectroscopy aided by laser-guide star adaptive optics for RCSGA0327, the brightest distant lensed galaxy currently known in the Universe. Due to the high lensing magnification of the system, these observations reach spatial scales of < 100 pc in the source-plane of the galaxy. The velocity field suggests we are witnessing a merger in progress, close in time to the first-pass encounter. Both the WFC3 images and the OSIRIS data show a clumpy morphology and resolve multiple individual star-forming regions. I measure the sizes, stellar masses, star formation densities and velocity dispersions of these clumps and find an offset from the scaling relations for local H II regions.

Indexing (document details)
Advisor: Gladders, Michael D.
Commitee: Chen, Hsiao-Wen, Gnedin, Nick, Harper, Al
School: The University of Chicago
Department: Astronomy and Astrophysics
School Location: United States -- Illinois
Source: DAI-B 74/02(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Astrophysics, Astronomy
Keywords: Galaxy evolution, Gravitational lensing, Star formation
Publication Number: 3526999
ISBN: 9781267611031
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