Integral field spectroscopy as a probe of galaxy evolution

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Adams, Joshua Jesse

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Optical spectroscopy and modeling are applied to four independent problems related to the structure and evolution of galaxies. The problems cover a broad range of look-back time and galaxy mass. Integral field spectroscopy with low surface brightness sensitivity is the tool employed to advance our understanding of the distribution, interplay, and evolution of the stars, dark matter, and gas. First, I review development and commissioning work done on the VIRUS-P instrument. I then present a large sample of galaxies over redshifts 1.9<z<3.8 selected solely through their Lyman-alpha flux. This work is done as a pilot survey to the Hobby-Eberly Telescope Dark Energy eXperiment (HETDEX). I create a redshift catalog of 397 galaxies discovered over 169 square arcsecs taken over 113 nights. Second, I study a high redshift (z=3.4) radio galaxy halo by mapping the Lyman-alpha velocity field. The signal extends far beyond the optical and radio extents of the system. Plausible, but non-unique, models are made to explain the Lyman-alpha signal that require a very large reservoir of neutral hydrogen (>= 10E12 solar masses). Third, I study the dark matter halo profile in a nearby late-type dwarf galaxy in the context of the "core-cusp" controversy. N-body simulations predict such galaxies to have cuspy dark matter halos, while HI rotation curves and more recent hydrodynamical simulations indicate that such halos may instead be strongly cored. I measure the spatially resolved stellar velocity field and fit with two-integral Jeans models. A cuspy halo is preferred from the stellar kinematics. The mass models from stellar and gaseous kinematics disagree. The gas models assume circular motion in an infinitely thin disk which is likely unrealistic. The stellar kinematics presented are the first measurements of a collision-less tracer in such galaxies. Fourth, I attempt to measure diffuse H-alpha emission, fluoresced by the metagalactic UV background, in the outskirts of a nearby gas rich galaxy. I do not make a detection, but the deep flux limit over a large field-of-view places the most sensitive limit to-date on the UV background's photoionization rate of Gamma(z=0)<1.7x10E-14 1/s at 5 sigma certainty.




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