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Astron. Astrophys. 362, 825-834 (2000)


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Dynamical and content evolution of a sample of clusters from z[FORMULA]0 to z[FORMULA]0.5

C. Adami 1,2, B.P. Holden 3, F.J. Castander 4,3, A. Mazure 1, R.C. Nichol 5 and M.P. Ulmer 2

1 LAM, Traverse du Siphon, 13012 Marseille, France
2 Department of Physics and Astronomy, NU, Dearborn Observatory, 2131 Sheridan, 60208-2900 Evanston, USA
3 Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, USA
4 Observatoire Midi-Pyrenees 14, Avenue Edouard Belin, 31400 Toulouse, France
5 Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA

Received 17 July 2000 / Accepted 31 August 2000

Abstract

In this paper, we present an analysis of the dynamics and segregation of galaxies in rich clusters from z[FORMULA]0.32 to z[FORMULA]0.48 taken from the CFHT Optical PDCS (COP) survey and from the CNOC survey (Carlberg et al. 1997). Our results from the COP survey are based upon the recent observational work of Adami et al. (2000a) and Holden et al. (2000) and use new spectroscopic and photometric data on six clusters selected from the Palomar Distant Cluster Survey (PDCS; Postman et al. 1996). We have compared the COP and CNOC samples to the ESO Nearby Abell Cluster Survey (ENACS: z[FORMULA]0.07).

Our sample shows that the [FORMULA] clusters have the same velocity dispersion versus magnitude, morphological type and radius relationships as nearby ([FORMULA]) Abell clusters. The z[FORMULA]0.48 clusters exhibit, however, departures from these relations. Furthermore, there appears to be a higher fraction of late-type (or bluer, e.g. Butcher & Oemler, 1984) galaxies in the distant clusters compared to the nearby ones.

The classical scenario in which massive galaxies virialize before they evolve from late into early type explain our observations. In such a scenario, the clusters of our sample began to form before a redshift of approximately 0.8 and the late-type galaxy population had a continuous infall into the clusters.

Key words: galaxies: clusters: general – cosmology: observations – cosmology: large-scale structure of Universe

Send offprint requests to: C. Adami (adami@obmara.cnrs-mrs.fr)

© European Southern Observatory (ESO) 2000

Online publication: October 30, 2000

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