Date of Award

5-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Committee Chair

Dimitrios Giannios

Committee Member 1

Matthew Lister

Committee Member 2

Maxim Lyutikov

Committee Member 3

Denes Molnar

Abstract

The bifurcation of Galactic Nuclei into active galactic nuclei (AGN) and low-luminosity accreting systems is ultimately related to the gas dynamics and therefore the observed emission. Relativistic jets in AGN produce bright and variable emission emanating across the electromagnetic spectrum. The ultra-fast variability, occurring on timescales of several minutes, observed from blazars, a subclass of AGN, pose tight constraints on theoretical models as they require compact objects characterized by fast motions and high Doppler boosting within the jet. Here, I report on the relativistic magnetic reconnection model as a source of blazar emission. By using the results of first principle numerical simulations of relativistic reconnection, I compute the emission produced by hundreds of radiating blobs containing magnetic fields and relativistic particles, the so-called plasmoids. The observed emission from low-luminosity AGNs, such as our own Galactic Center, is produced by an radiatively inefficient accretion flow. Theoretical models of radiatively inefficient accretion flows have been show to accurately account for the observed spectrum and luminosity from our Galactic Center. However, the physical properties of the accretion flow as well as the origin of the gas remain elusive. Here, I explore several models for indirectly probing the properties of the gas and provide a natural origin for the population of relativistic particles while providing several key observational signatures.

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