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The environmental dependence of galaxy properties in the local universe: effects of local and global environment

Published online by Cambridge University Press:  06 October 2004

M. Tanaka
Affiliation:
Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan email: [email protected]
T. Goto
Affiliation:
Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan email: [email protected] Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686, USA
S. Okamura
Affiliation:
Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan email: [email protected]
K. Shimasaku
Affiliation:
Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan email: [email protected]
J. Brinkman
Affiliation:
Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA
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Abstract

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We investigate the environmental dependence of galaxy properties in the local universe based on the data of the Sloan Digital Sky Survey. We focus on how star formation and morphology of galaxies correlate with luminosity, local environment, and global environment. We find that galaxy properties abruptly change at a critical local density of $\log \Sigma_{\rm crit}\sim 0.4\ {\rm galaxies}\ h_{75}^{2}\ \rm Mpc^{-2}$. The ‘break’ at the critical density is found only for faint galaxies ($M^*_r+1 < M_r < M^*_r+2$). Bright galaxies ($M_r < M^*_r+1$) show no break. That is, the star formation-density and the morphology-density relations depend on galaxy luminosity. Next, we focus on global environment, i.e., richness of galaxy groups and clusters. Most galaxies are not forming stars in groups as poor as $\sigma\sim200\rm\ km\ s^{-1}$. This fact suggests that environmental mechanisms that are effective only in rich clusters, such as ram-pressure stripping of cold gas and harassment, have not played a major role in suppressing galaxy star formation. Our results may suggest that evolution of bright galaxies is not strongly related to galaxy systems such as groups and clusters. On the other hand, evolution of faint galaxies may have a close connection.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Type
Contributed Papers
Copyright
© 2004 International Astronomical Union