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Evolution of the early-type galaxy fraction in clusters since z = 0.8

Simard, L. and Clowe, D. and Desai, V. and Dalcanton, J. J. and von der Linden, A. and Poggianti, B. M. and White, S. D. M. and Aragón-Salamanca, A. and De Lucia, G. and Halliday, C. and Jablonka, P. and Milvang-Jensen, B. and Saglia, R. P. and Pelló, R. and Rudnick, G. H. and Zaritsky, D. (2009) Evolution of the early-type galaxy fraction in clusters since z = 0.8. Astronomy and Astrophysics, 508 (3). pp. 1141-1159. ISSN 0004-6361.

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We study the morphological content of a large sample of high-redshift clusters to determine its dependence on cluster mass and redshift. Quantitative morphologies are based on PSF-convolved, 2D bulge+disk decompositions of cluster and field galaxies on deep Very Large Telescope FORS2 images of eighteen, optically-selected galaxy clusters at 0.45 < z < 0.80 observed as part of the ESO Distant Cluster Survey (“EDisCS”). Morphological content is characterized by the early-type galaxy fraction f_(et) , and early-type galaxies are objectively selected based on their bulge fraction and image smoothness. This quantitative selection is equivalent to selecting galaxies visually classified as E or S0. Changes in early-type fractions as a function of cluster velocity dispersion, redshift and star-formation activity are studied. A set of 158 clusters extracted from the Sloan Digital Sky Survey is analyzed exactly as the distant EDisCS sample to provide a robust local comparison. We also compare our results to a set of clusters from the Millennium Simulation. Our main results are: (1) the early-type fractions of the SDSS and EDisCS clusters exhibit no clear trend as a function of cluster velocity dispersion. (2) Mid-z EDisCS clusters around σ = 500 km s^(-1) have f_(et) ≃ 0.5 whereas high-z EDisCS clusters have f_(et) ≃ 0.4. This represents a ~25% increase over a time interval of 2 Gyr. (3) There is a marked difference in the morphological content of EDisCS and SDSS clusters. None of the EDisCS clusters have early-type galaxy fractions greater than 0.6 whereas half of the SDSS clusters lie above this value. This difference is seen in clusters of all velocity dispersions. (4) There is a strong and clear correlation between morphology and star formation activity in SDSS and EDisCS clusters in the sense that decreasing fractions of [OII] emitters are tracked by increasing early-type fractions. This correlation holds independent of cluster velocity dispersion and redshift even though the fraction of [OII] emitters decreases from z ~ 0.8 to z ~ 0.06 in all environments. Our results pose an interesting challenge to structural transformation and star formation quenching processes that strongly depend on the global cluster environment (e.g., a dense ICM) and suggest that cluster membership may be of lesser importance than other variables in determining galaxy properties.

Item Type:Article
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URLURL TypeDescription
Desai, V.0000-0002-1340-0543
Poggianti, B. M.0000-0001-8751-8360
Rudnick, G. H.0000-0001-5851-1856
Zaritsky, D.0000-0002-5177-727X
Additional Information:© ESO 2009. Received 18 October 2007; accepted 6 October 2009. We are thankful to the anonymous referee for suggestions that greatly contributed this paper. We have benefitted from the generosity of the ESO/OPC. G.R. thanks Special Research Area No 375 of the German Research Foundation for financial support. The Millennium Simulation databases used in this paper and the web applications providing access to them were constructed as part of the activities of the German Astrophysical Virtual Observatory. Funding for the creation and distribution of the SDSS Archive has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the US Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society. The SDSS Web site is The SDSS is managed by the Astrophysical Research Consortium (ARC) for the Participating Institutions. The Participating Institutions are The University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, The Johns Hopkins University, the Korean Scientist Group, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck- Institute for Astrophysics (MPA), New Mexico State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington. The Dark Cosmology Centre is funded by the Danish National Research Foundation.
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European Southern Observatory (ESO)UNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
Subject Keywords:galaxies: fundamental parameters; galaxies: evolution; galaxies: clusters: general
Issue or Number:3
Record Number:CaltechAUTHORS:20100114-113748451
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Official Citation:Evolution of the early-type galaxy fraction in clusters since z = 0.8 L. Simard, D. Clowe, V. Desai, J. J. Dalcanton, A. von der Linden, B. M. Poggianti, S. D. M. White, A. Aragón-Salamanca, G. De Lucia, C. Halliday, P. Jablonka, B. Milvang-Jensen, R. P. Saglia, R. Pelló, G. H. Rudnick and D. Zaritsky A&A 508 (3) 1141-1159 (2009) DOI: 10.1051/0004-6361/20078872
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17181
Deposited By: Jason Perez
Deposited On:14 Jan 2010 21:26
Last Modified:03 Oct 2019 01:24

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