Dissertations, Theses, and Capstone Projects

Date of Degree

9-2024

Document Type

Dissertation

Degree Name

Ph.D.

Program

Physics

Advisor

Matt O'Dowd

Committee Members

Giorgos Vernardos

Timo Anguita

Saavik Ford

Barry McKernan

Subject Categories

Cosmology, Relativity, and Gravity | External Galaxies

Keywords

Quasars, AGN, gravitational lensing

Abstract

Active Galactic Nuclei (AGN) are generally believed to be supermassive black holes (SMBHs) at the center of galaxies which are actively accreting material from the host galaxy. Through this process, they emit radiation across the electromagnetic spectrum both as a smooth continuum and emission lines. However, there is a great variety of the signals we observe–some faint, some bright, some variable and others steady. The wide array of signals produced by AGN is believed to encode both the geometry and the physics surrounding these SMBHs, making them a valuable target for understanding the high gravity limit, their feedback mechanisms to the host galaxy, and a probe of cosmology at the largest scales. Throughout this dissertation, I will be addressing the issue of how to practically model these AGN and their variability. I will present Amoeba, a modeling software for AGN variability aimed to self-consistently join together multiple components of AGN into one coherent model. I will discuss work done on studying this variability and what it can tell us about the AGN itself. I will demonstrate the importance of joint modeling of both intrinsic variability and microlensing–another source of variability that arises in strong gravitationally lensed systems. In doing so, we will take another step forward in our understanding of AGN and their greater connection to the Universe.

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