College - Author 1

College of Science and Mathematics

Department - Author 1

Physics Department

Degree Name - Author 1

BS in Physics



Primary Advisor

Vardha Bennert, College of Science and Mathematics, Physics Department


Active Galactic Nuclei (AGN) are some of the brightest objects within our Universe. Most galaxies contain a supermassive black hole (SMBH) at their center, but not all are powered by active accretion which can form an AGN. Due to the conservation of angular momentum, dust and gas rotate around the SMBH to form a disk. The large gravitational potential energy from the SMBH is converted into heat through friction, which produces a hot and luminous source of light. As a result, the SMBH is unresolved. Through a technique known as reverberation mapping (RM), the mass of the SMBH has been determined for a sample AGNs. In this thesis, I am analyzing 19 of these AGNs images obtained by the Hubble Space Telescope (HST). Specifically, I use 2D analytical fitting programs called GALFIT to model the host galaxies and determine the light profiles for different components, such as PSF, bulge, disk, and bar. Traditionally, GALFIT has been used to model host galaxies as it is very user-friendly. In this thesis, a comparison is made between the best-fit results of GALFIT with a state-of-the-art program called lenstronomy. Lenstronomy was originally developed to model galaxy lenses, but it can be modified to model AGN host galaxies. Lenstronomy has the advantage of requiring less user interaction in the fitting procedure and offers more reliable errors than GALFIT. In this study, we find that, overall, GALFIT and lenstronomy provide comparable results in modeling the host galaxy. There is overall agreement in fitting the magnitude and effective radii for the present components of the galaxies. However, some discrepancies arise in determining the number of components to model a galaxy, so the best model is determined by GALFIT due to greater user interaction. The ultimate goal is to study the relation between the mass of the SMBH and different properties of the host galaxy, such as stellar-velocity dispersion and spheroid luminosity to better understand the evolution of galaxies. The results presented here are the first step towards this goal.