Author
Pucha, RagadeepikaIssue Date
2023Advisor
Juneau, StephanieDey, Arjun
Metadata
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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
Low-mass "dwarf" galaxies (stellar mass, M* <= 3 x 10^9 Msun), being ubiquitous in the universe, are excellent laboratories for testing critical components of galaxy evolution. The current and future photometric and spectroscopic surveys, including the Sloan Digital Sky Survey (SDSS), the Dark Energy Survey (DES), the Dark Energy Spectroscopic Instrument (DESI) survey, and the Legacy Survey of Space and Time (LSST) are facilitating the study of these galaxies in great detail. In this dissertation, I probe three different aspects of galaxy evolution using dwarf galaxies. Firstly, by conducting the widest (1.5 deg diameter field of view) and the deepest (down to g ~ 26.5 mag) survey of resolved stars in a Local Group dwarf galaxy, IC 1613, I found evidence of hierarchical accretion in the galaxy. This is an important first step in understanding structure formation in dwarf galaxies. Secondly, I demonstrated that the compact morphologies of Lyman-Alpha Emitters (LAEs), i.e., low-mass, high-redshift galaxies, are key to Ly-alpha escape, a process that is crucial for understanding the epoch of reionization. Finally, using an unprecedented spectroscopic sample of ~190,000 low-mass galaxies from the DESI survey, I identified >2,500 active galactic nuclei (AGNs) out to z ~ 0.45, more than tripling the existing census of optical dwarf AGN candidates. Compared to previous systematic searches, I have extended the discovery space of such candidates to lower galaxy masses and to higher redshifts. Additionally, I extended the black hole (BH) mass - galaxy stellar mass (M_BH - M*) scaling relation down to log (M*/Msun) ~ 8.4. This statistical sample of AGN in low-mass galaxies will have important implications for the study of galaxy-BH co-evolution at the low-mass end of the galaxy mass function. Furthermore, I created four publicly available Jupyter Notebooks that show how to access and analyze photometric and spectroscopic data for the scientific analysis of galaxies.Type
Electronic Dissertationtext
Degree Name
Ph.D.Degree Level
doctoralDegree Program
Graduate CollegeAstronomy