## Theses and Dissertations

12-2017

Dissertation

#### Degree Name

Doctor of Philosophy in Physics (PhD)

Physics

Julia Kennefick

Claud H. Lacy

#### Second Committee Member

William Oliver III

Tim Kral

#### Keywords

Active galactic nuclei, AGN feedback, AGN spectral energy distribution, galaxy evolution, spiral galaxies

#### Abstract

I have investigated the energy output of active galactic nuclei (AGN) in order to understand how these objects evolve and the impact they may have on host galaxies. First, I looked at a sample of 96 AGN at redshifts $z \sim 2, 3,$ and $4$ which have imaging and thus luminosity measurements in the $griz$ and $JHK$ observed wavebands. For these galaxies, I have co-epochal data across those bands which accounted for variability in AGN luminosity. I used the luminosity measurements in the five bands to construct spectral energy distributions (SED) in the emitted optical-UV bands for each AGN. I compared the SED to assumptions previously made about quasars and looked for correlations between SED and other AGN and galaxy properties. Second, I used spectra of the broad line region (BLR) of Type 1 AGN to estimate the mass of the central supermassive black hole ($M_{BH}$). I found a sample of Type 1 AGN that reside in spiral galaxies in order to explore the relationship between $M_{BH}$ and pitch angle ($\phi$), a measurement of how tightly wound the spiral arms are. Type 1 AGN offer a method to estimate $M_{BH}$ at higher redshift than previous studies of the $M_{BH}$-$\phi$ relation. I was able to look at the evolution in the $M_{BH}$-$\phi$ relation which has implications for galaxy formation as well as AGN feedback.

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