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[51.02] The Stellar Mass, Metallicity, and AGN content of SDSS Galaxies as a Function of Local Environment

C. A. Tremonti (JHU / Steward Observatory), T. M. Heckman (JHU), G. Kauffmann, S. Charlot, J.. Brinchmann, S. White (MPA), M. Seibert (JHU)

We utilize SDSS imaging and spectroscopy of ~115,000 galaxies to study the relation between stellar mass, gas phase metallicity and galaxy environment. To obtain very accurate emission line flux measurements we use the Bruzual and Charlot 2003 models to fit and subtract the stellar continuum of each spectrum. For ~30% of the sample we are able to measure [OIII] 5007, H-beta, [N II] 6584, and H-alpha. Standard line diagnostics are used to classify the galaxies as AGN or star forming. For the ~25,000 star forming galaxies, we derive metallicites from the strong optical nebular lines. We estimate mass-to-light ratios from the 4000 A break and the H-delta absorption and use these with the z-band luminosity to calculate stellar masses. We examine the relation between stellar mass and metallicity in 3 broad bins of local galaxy overdensity which can be loosely interpreted as cluster, group, and field environments. We also examine the fraction of AGN which reside in these environments.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.