Active Galactic Nuclei and the Correlated Properties of Neighboring Galaxies

When a galaxy's central supermassive black hole is actively accreting matter, it becomes an active galactic nucleus (AGN). AGN are most commonly found in the "green valley", a region of relatively low density on a color/magnitude diagram of galaxies located between the denser red and blue sequences. I performed an analysis on a sample of galaxies collected from the Sloan Digital Sky Survey (SDSS) database in search of the properties possessed by a target galaxy's neighboring galaxies that correlate with the probability of finding an AGN in that target. I found that, among galaxies with AGN, galaxies with more neighbors – galaxies within a projected distance of 0.5 megaparsecs (Mpc) – tend to be redder than galaxies with few neighbors for the majority of the color range in my sample; however, among galaxies without AGN, this trend only exists outside of the green valley. Additionally, I found that galaxies with fewer neighbors are more likely to contain AGN than galaxies with many neighbors.No embargoAcademic Major: Astronomy and Astrophysic