Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
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Item From Tantrums to Transformations: AGN Transients Discovered with the Zwicky Transient Facility(2021) Frederick, Sara; Gezari, Suvi; Astronomy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation work has consisted of searches for extreme AGN-related outbursts during Phase I of the Zwicky Transient Facility (ZTF) survey, which has been a ground-breaking wide-field instrument for the real-time detection and regular cadence monitoring of transients in the Northern Sky. Transients found to be nuclear through photometric filtering were vetted by humans and coordinated for prompt follow-up with various rapid robotic, spectroscopic, and high energy resources, to understand the nature of the galaxy centers undergoing flares and the appearance of spectral features. Findings from this unprecedentedly high-volume data stream were often serendipitous, and led to surprising new avenues for study, including 1) the establishment of a new observational class of quiescent galaxies caught turning into quasars, 2) the discovery of a preponderance of smooth and high-amplitude optical transients hosted in NLSy1s, and 3) a framework for distinguishing extreme AGN variability from other transients in AGN. We present the results of these observations, including candidates for TDEs in AGN, changing-look AGN caught "turning-on", as well as members of the new emerging observational class of flares in Narrow-Line Seyfert 1 (NLSy1) galaxies associated with enhanced accretion (Trakhtenbrot et al. 2019). We compared the properties of these samples of flares to previously reported changing-look quasars and Seyfert galaxies, confirmed that they are a unique observational class of transients related to physical processes associated with the central supermassive black hole's accretion state, and considered the observations in the context of the physical interpretations for a range of related transients from the literature. With these unique sample sets, we also aim to understand why we have found certain galaxy types to preferentially host the sites of such rapid enhanced flaring activity, and attempt to map out the innermost environment of the accretion events. These pathfinding studies enabled with ZTF have the potential to guide how these exceptional moments of AGN evolution will be systematically discovered in future large area surveys such as the Vera C. Rubin Observatory.Item BRILLER SUR SCÈNE : L'ASTRONOMIE DANS LE THÉÂTRE DU GRAND SIÈCLE(2014) Arnaud, Cybele; Campangne, Hervé Thomas; French Language and Literature; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)January 5th, 1634, the news of Galileo's condemnation by the Roman Catholic Church for his heretical belief in heliocentric theories -theories that postulate that the Earth orbits the Sun- reach France. As the professors of the Sorbonne condemn Galileo, as René Descartes, ever-cautious, chooses to forgo publishing his Treatise on the World, an ever increasing number of French writers turn to fiction to prove, attack, or simply present astronomical and cosmological theories to their audience. While much has been written about the new astronomy's relationship to poetry, proto-science fiction and vulgarization through novelization of scientific knowledge, its presence on the French stage, in comedies and ballets, has been mostly ignored by the scholarship. This thesis constructs a timeline of "natural philosophy theatre", tracking the movement of the sun and the earth and the representation of the theories elaborated by Copernicus, Tycho Brahé and Descartes through plays and ballets published in the 17th century and beyond, in order to analyze the function of laughter in the context of the scientific revolution. The following questions will be answered: How is the new astronomy presented on stage, both in comedies and ballets? What role does laughter play in the representation of science? Is it simply used to challenge the audience's beliefs? Is dance's only purpose to mimic the orbits of the planets, or does it hold a deeper meaning? What, if any, is the greater purpose of including scientific knowledge in theater?Item Sources of Self-efficacy in an Undergraduate Introductory Astronomy Course for Non-science Majors(2005-12-02) Carter, Brooke; McGinnis, James R; Curriculum and Instruction; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The role of the astronomy laboratory on non-science major student self-efficacy is investigated through combining quantitative and qualitative methodologies. The Astronomy Diagnostic Test 2.0 is distributed to an introductory astronomy laboratory for non-science major class in the Spring of 2005. The ADT 2.0 is used to draw comparisons between interview subjects and the remaining class. Eight subjects were interviewed three times throughout the semester in order to determine the important contributing factors to the subjects' self-efficacy beliefs. Results of the quantitative data suggest that the interview participants' general science self-efficacy did not significantly increase over the course of the semester. Results of the quantitative data suggest the most important contributor to the subjects' self-efficacy in the laboratory is verbal persuasion. The results of this limited study suggest that the astronomy laboratory experience is a strong contributor to student self-efficacy beliefs.