Dynamical and content evolution of a sample of clusters from z0 to z0.5
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
Received 17 July 2000 / Accepted 31 August 2000
In this paper, we present an analysis of the dynamics and segregation of galaxies in rich clusters from z0.32 to z0.48 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: z0.07).
Our sample shows that the clusters have the same velocity dispersion versus magnitude, morphological type and radius relationships as nearby () Abell clusters. The z0.48 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
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© European Southern Observatory (ESO) 2000
Online publication: October 30, 2000