Quasars are an example of a rare active galaxy, those with a supermassive black hole accreting material at the fastest possible rate, except quasars have accretion disks so bright that it outshines the entire host galaxy. Currently, little is known about quasar morphology or what causes quasars to exist in the first place. Understanding what the host galaxy looks like will shed light onto the cause of these objects. We model images obtained from the Hubble Space Telescope of 22 nearby quasar galaxies and their immediate galaxy neighbors using an image analysis algorithm called GALFIT. This algorithm fits parametric functions to create galaxy light profiles from two-dimensional images, determining the best-fit model via chi-squared minimization. We subtract our best-fit model from the data to create residual light maps which provide visual and quantitative details on the goodness of the fit. We present the process of creating the models, as well as examples of model fits and the residual maps.
Raub, Kaitlyn, "Determining Quasar Galaxy Morphologies Using GALFIT" (2020). 2020 Undergraduate Presentations. 21.