Date of Graduation

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Space & Planetary Sciences (PhD)

Degree Level

Graduate

Department

Space & Planetary Sciences

Advisor/Mentor

Kennefick, Julia D.

Committee Member

Kennefick, Daniel J.

Second Committee Member

Li, Jiali

Third Committee Member

Roe, Larry A.

Keywords

Astrophysics; Black Holes; Cosmology; Galaxy Evolution; Ring Galaxies; Spiral Galaxy Structure

Abstract

This dissertation pertains to the geometric structure of late type (spiral) galaxies, specifically on the relation between the logarithmic spiral pitch angle of the galactic spiral arms with other properties of the galaxy, such as central Supermassive Black Hole (SMBH) mass. Our work continues a study of the Black Hole Mass Function (BHMF) in local galaxies by recording the pitch angles of spiral galaxies with lower surface brightness than were previously included. We also conduct a case study on the structure of an interestingly shaped galaxy, UGC 4599. Previous studies on the topic of spiral arm pitch angles have measured the pitch angle of galaxies using a variety of image analysis techniques. Here the effectiveness of two of these techniques are assessed under different galaxy conditions and their errors and failure modes are probed as the measurement characteristics of simulated galaxies are manipulated and degraded. This is done for the purpose of recognizing and accounting for the limits of techniques for measuring the pitch angles of galaxies as they increase in redshift or decrease in surface brightness or angular resolution (pixel size). As a result, imaging based relations in galaxy structure may be applied to extend measurements from the local universe to greater distances as long as image degradation with distance is accounted for. In exploring populations of galaxies, errors in distribution studies might result from gaps in selection; galaxies with too little apparent structure or too faint a surface brightness to be recognized as spirals and included in the study. Errors might also result from inaccuracy or failure on the measurement side, where low resolution, low surface brightness galaxies produce pitch angle measurements characterized by higher failure rates and higher associated errors for successful measurements. We work to employ new techniques to minimize these errors as well as understand and account for their effects on the distributions being measured.

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