BA, Oberlin College, 2022, Physics and Astronomy

In this thesis, I introduce a method to identify and characterize the effects of active galactic nuclei (AGN) on the spectra of nearby star-forming regions. I analyze spatially-resolved areas of galaxies called “spaxels” within Data Release 15 of the Sloan Digital Sky Survey (SDSS) with the goal of locating those which are physically close to AGN. I find those spaxels with calculated metallicities which lie adjacent to AGN-flagged spaxels and characterize their metallicity values relative to the spaxels which are not adjacent to AGN-flagged spaxels, using a total of 11 separate metallicity calibrations. I find that the current methods to mask AGN-influenced regions for large-scale investigation are, in general, robust, as the largest median deviation between metallicities in border spaxels and those in non-border spaxels is 0.0467 dex. The largest mean difference in metallicity between border and non-border spaxels is 0.0522 dex with a standard deviation of 0.0590 dex. However, on a spaxel-by spaxel basis, I find that the differences in metallicity between border spaxels and non-border spaxels can be as large as 0.9350 dex. These results are concerning for spaxel-by-spaxel analysis, and indicate the need for an improved masking process in the future.

Committee: Jillian Scudder (Advisor) Subjects: Astronomy; Astrophysics; Physics

Master of Science, The Ohio State University, 2021, Mechanical Engineering

Spectroscopy is one of the more common scientific practices in the realm of astronomy because it allows astronomers to deduce properties of stars, galaxies, and other celestial objects, such as mass, temperature, chemical composition, redshift, presence of orbiting bodies, and more. Specifically, multi-object spectroscopy has become popular in ground-based astronomy for accumulating large quantities of data. This data is collected with optical fibers located at a telescope's focal plane that then send the collected light to instruments called spectrographs for analysis. Up until recently, these fibers were always fixed in stationary configurations. Now, the astronomy community has begun working with fiber positioning robots that can dynamically and automatically reconfigure the fibers. This functionality allows for more observing time, and thus more data collected, each night that previously would have been spent manually reconfiguring fibers. One such project employing this new strategy is the Sloan Digital Sky Survey (SDSS-V). A lot of work goes into preparing instruments with robotic fiber positioners, and a great deal of effort is put in to retire as much risk as possible before delivery to observatories. This thesis discusses the development and implementation of an optical measurement system that serves to measure the positional accuracy performance of the fiber robots and that is used to develop and exercise the software package to be used with the Focal Plane System instruments of SDSS-V prior to arrival on-site. Specifically, the fixed fiber-illuminated fiducial metrology, opto-mechanical design of the measurement system, and the development of the optical transform to be used to evaluate robot positional accuracy is detailed herein. This lab-based pre-commissioning strategy is unique to the subset of these instruments with connectorized fibers since they can operate without being interfaced with a telescope and spectrograph(s). From a software (open full item for complete abstract)

Committee: Richard Pogge (Committee Member); Giorgio Rizzoni (Advisor) Subjects: Astronomy; Mechanical Engineering; Optics

MA, Kent State University, 2013, College of the Arts / School of Art

John Sloan and Stuart Davis summered in Gloucester, Massachusetts from 1915 through 1918 at the Red Cottage. Their time spent in Gloucester was used to experiment with new European styles that emerged from the 1913 Armory Show. Before summering in Gloucester, both artists belonged to the Ashcan School in New York, led by their teacher, Robert Henri who taught them to paint the world around them. As a result, they painted grim, realistic, and unconventional subject matter in New York and their palettes were dark and saturated. Hardesty G. Maratta's color theory, a palette of premixed colors, with a chromatic circle, which guided artists in choosing hues, the 1913 Armory Show, and the landscape and pristine light of Gloucester provided them with new inspiration, which altered their art. Both artists lighten their color palettes and painted panoramic views. Even though they painted the same scenery and shared the same inspirations, their oeuvres were distinctly different. Sloan painted portraits, landscapes, and genre scenes, while Davis painted landscapes and Cubist-inspired paintings, including picturesque and mundane settings. This thesis discusses their progression as artists in Gloucester as their artwork has never been extensively discussed together in the vast scholarly literature devoted to these two American masters.

Committee: Carol Salus PhD (Advisor); Diane Scillia PhD (Committee Member); Gustav Medicus PhD (Committee Member); Navjotkia Kumar PhD (Committee Member) Subjects: Art History

Bachelor of Sciences, Ohio University, 2010, Physics and Astronomy

Galaxy clusters are the largest structures in the Universe, and the evolution of galaxy cluster mass profiles is a useful tool for constraining cosmological models. Most methods established for obtaining a mass profile of a cluster of galaxies assumes the clusters obey the virial theorem; however, the majority of clusters are observed to contain non-virialized substructures. Zaritsky outlined a timing argument for obtaining mass profiles (Zaritsky, 1989). The timing argument assumes that at a time t = 0, every galaxy in the cluster was concentrated at one point, and then simultaneously exploded outward. The current position of each galaxy with respect to the cluster center is determined only by Newtonian gravitation. Zaritsky applied this method to the local group and obtained reasonable mass profiles (Zaritsky, 1989). We test this new method for mass measurement and compare our results to values obtained using virialized methods. We apply this timing argument to a sample of galaxy clusters of nearby redshift (from z~0.05 to z~0.2) taken from the Sloan Digital Sky Survey, using a 12 Mpc radius (a region larger than the typical infall radius) for each cluster. We chose clusters from a paper written by Popesso that contained published velocity dispersions for each cluster (Popesso, 2006). The profiles we acquire through the timing argument have a useful astronomical application because they rely only on infalling galaxies in the cluster, forgoing the virial theorem. We estimate a mass based on these profiles and use that mass to calculate a velocity dispersion in each cluster. Our velocity dispersions are compared to published values. Our comparison shows that this method for mass measurement gives reasonable velocity dispersions when applied to a large sample of galaxies. There is no clear systematic offset between our data set and the published data set, and many variables within this method leave room for large errors.

Committee: Douglas Clowe PhD (Advisor) Subjects: Astronomy; Astrophysics; Physics