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Andrew Cooper
Department of Physics
University of Missouri-Kansas City
Dr. Daniel McIntosh
Abstract
The AGN activity of major mergers and post-merger remnants among massive galaxies in the local universe is investigated in this study. A merger-fueled AGN and its subsequent quenching of star formation is postulated to be a central mechanism in explaining the formation and growth of the red and dead spheroid galaxy population over cosmic time. Starting with a volume- limited (z<0.08) and stellar mass-limited (Mstar > 1010 Msun) sample of 32,500 emission-line galaxies from the SDSS, over 900 galaxy pairs (mergers), and 100 individual systems (remnants), with tidal signatures associated with major merging activity were identified. Using nebular emission line data based on SDSS fiber spectra from the MPA-JHU Emission Line Analysis, and employing a variety of emission-line flux ratio diagnostics that allows the separation of the sample data into HII, AGN (both Seyferts and LINERs) and composite spectral types, mergers and remnants to each other and to the non-merging galaxy population were compared. At the mass cut used, the observation that galaxies that emit strong emission lines (S/N>3) never have purely star-forming central spectra as found in lower-mass emission-line systems is noted. More than a third of the mergers and remnants in the sample data were found to have measurable AGN activity in their central spectra; nearly 30% of each type are LINERs. The results presented indicate that AGN activity is common among high-mass mergers, with higher activity strength relative to non-merging systems.
Andrew Cooper is a senior in Physics at the University of Missouri - Kansas City. Andrew grew up in the small town of Blairsville, which is located under the dark skies of Northern Georgia. He moved to Harrisonville, Missouri in 2004 and began his college career at the age of sixteen in 2006 at Longview Community College. Astronomy has always been a strong interest of Andrew's since he was very young, so when he started college he set out to work in astronomy and physics. In 2008 Andrew transferred to UMKC to begin his major-based course work. Since transferring, he has been an active member of UMKC's Honors Program, an officer in the Society of Physics Students chapter at UMKC, and a recipient of the James M. Phillips Scholarship in Physics. In 2009, Andrew joined UMKC's Galaxy Evolution Group (GEG) and has been working for Dr. Daniel McIntosh ever since. By having the chance to work in research as an undergraduate for the GEG and experience what life as an astronomer is like, Andrew has definitely decided that he wants to attend graduate school in astrophysics. Andrew's overall research interest is in high-energy astrophysics and he would ultimately like to research the dynamic behavior of stellar remnants or various types of active galactic nuclei. |
