Building Relationships: (1) Unifying Observations and Simulations to Measure Dark Matter Accretion & (2) Inclusivity-Driven Designs for General-Education Astronomy Courses
Author
O'Donnell, Christine AnneIssue Date
2020Advisor
Behroozi, Peter
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The University of Arizona.Rights
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.Abstract
My dissertation is a combination of two separate projects: Part I: Unifying Observations and Simulations to Measure Dark Matter Accretion Under the current paradigm for galaxy formation, galaxies grow in the centers of halos composed of dark matter. As a dark matter halo accretes more material, the halo’s gravitational potential well deepens, funneling gas into the central galaxy and potentially leading to galaxy growth. However, models of these processes predict very different correlations between dark matter accretion and galaxy star formation due to feedback processes such as winds from supernovae and supermassive black holes. By combining theoretical simulations with archival observational data, we present observational constraints on dark matter accretion in isolated Milky Way-mass galaxies. Our new techniques rely on the fact that the deepening of the halo’s gravitational potential will also have a strong and predictable impact the orbits of satellite galaxies, and so we can infer accretion rates from the observed distributions of satellite galaxies. Our results show that dark matter accretion and star formation in Milky Way-mass galaxies in the recent Universe ($z \sim 0$) are not positively correlated, thus favoring models that predict strong feedback suppresses fresh gas accretion, and so star formation in these galaxies is instead fueled by recycled gas. Future observational surveys and improvements to theoretical models will enhance our analysis by providing a larger sample of galaxies from which to measure these correlations, as well as providing opportunities to constrain correlations between dark matter accretion and other galaxy properties, such as metallicity and presence of active galactic nuclei (AGN). Part II: Inclusivity-Driven Designs for General-Education Astronomy Courses General-education college astronomy courses offer instructors a unique audience and a unique challenge. For many students, such a course may be their first time encountering a standalone astronomy class, yet it is also likely one of the last science courses they will take. Thus, in a single semester, the primary goals of a general-education course include both imparting knowledge about the Universe and giving students some familiarity with science. In traditional course environments, students can compartmentalize information into separate "life files" and "course files" rather than integrating information into a coherent framework. Our project aims to transcend the boundary between those categories. Our strategy is to create an inclusive course that encourages and respects diverse points of view and empowers students to build connections between the course content and their personal lives and identities. Based on results from implementing these techniques in a general-education introductory cosmology course taught at the University of Arizona in Spring 2019, we present a set of guiding principles that can inform future course designs.Type
textElectronic Dissertation
Degree Name
Ph.D.Degree Level
doctoralDegree Program
Graduate CollegeAstronomy