NOAO >   Observing Info >   Approved Programs >   2004A-0306

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Proposal Information for 2004A-0306


PI: Christopher Ryan, York University, cjryan@yorku.ca
Address: Department of Physics and Astronomy, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada

CoI: Michael De Robertis, York University

Title: NIR Spectroscopy and Imaging of Violently Interacting Galaxies

Abstract: There is substantial evidence based on optical spectroscopy that the fraction of AGN in violently interacting galaxies is no greater than the fraction found in field galaxies, despite the widely held belief that nuclear activity is closely related to galaxy-galaxy interactions. The nuclei of such strongly interacting systems are especially likely to be sites of enhanced star formation and contain significant amounts of dust, however. This proposal employs near infrared spectral diagnostics, chiefly the ratio [Fe II] 1.644 (mu)m/Br(gamma) and emission-line widths, to determine whether the centers of galaxies in our sample - galaxies that have not yet been unambiguously classified optically - contain an active nucleus that may be significantly attenuated. We will use FLAMINGOS to obtain simultaneous, modest-resolution HK spectra for ~ 15 strongly interacting systems at relatively low redshift to classify the nuclear emission mechanism. By dividing the sample into three levels of merger maturity, we will be able to follow the evolution of the onset of nuclear activity, if indeed it exists. In order to study the details of the merging process and the behavior of the old stellar populations, we also will take K-band images of these systems. These data will also be used with R-band data already in hand to detect areas of enhanced attenuation and star formation in the interacting systems, as well as describe the large- scale environments in which the interactions are taking place.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2004A-0306

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