Seeing Red: The Present and Future of mid-IR AGN Selection with Optical Spectroscopy
Author
Hviding, Raphael ErikIssue Date
2023Advisor
Hainline, Kevin N.Rieke, Marcia J.
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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
Active Galactic Nuclei (AGNs) are central to the evolution of galaxies. The accretion of gas onto supermassive black holes (SMBHs) produces ionizing radiation that can outshine the host galaxy, potentially inhibiting star formation or removing gas and dust through feedback. However, the selection of AGNs remains incomplete, with \rev{in-depth} selections limited to small areas and larger samples contaminated by star-forming galaxies or biased against obscured and/or low-luminosity SMBH accretion. In particular obscured AGNs may form a vital stage in galaxy-SMBH coevolution. All-sky mid-infrared (mid-IR) surveys from the Wide-field Infrared Survey Explorer (WISE) present the opportunity to select the largest samples of AGNs, particularly obscured systems. However, the advent of new large-area photometric surveys without corresponding spectroscopy or more sensitive mid-IR missions necessitate the advancement in AGN selection methodologies using existing mid-IR data. In this dissertation I explore the current and future efforts to select AGN samples from mid-IR WISE data validated with optical spectroscopy. I assemble and fit a sample of nearly half-a-million galaxies with spectra in order to develop a new mid-IR criterion to select more complete samples of AGNs at comparable accuracies to existing samples. Furthermore, I conduct a spectroscopic campaign with MMT Hectospec to validate machine-learning selected AGN candidates from WISE photometry paired with deep optical imaging from Hyper Surpime Cam, demonstrating the efficacy of the methodology at recovering large samples of AGNs, in particular obscured sources. Finally, I perform a spatially resolved spectroscopic study of the Seyfert II galaxy NGC 1068 using Fabry Pérot interferometry to study the kiloparsec-scale ionized features in the galaxy, shedding light on obscured AGN activity. This thesis explores our understanding of mid-IR AGN selection, especially for obscured systems, and the galactic scale effects of SMBH growth through optical spectroscopic samples and spatially resolved spectroscopy.Type
Electronic Dissertationtext
Degree Name
Ph.D.Degree Level
doctoralDegree Program
Graduate CollegeAstronomy