Comments on the Reality of the Butcher-Oemler Effect
We propose that some of the evidence, especially recent spectroscopic data, for evolution in the properties of galaxies in the central cores of high redshift clusters remain questionable. Problems include biased selection of the clusters, contamination by extraneous galaxies, and non-inclusion of several corrections including the expansion of the universe. In particular, we suggest that clusters viewed approximately in the plane of flattened superclusters will preferentially be selected, thus magnifying the contamination by other clusters and “field” galaxies. The ratio of the accepted volume to that of the cluster core may easily reach beyond 400 for redshifts z greater than 0.3. Reasonable assumptions on the density structure of clusters and superclusters predict 10% or more contamination as observed.
KeywordsCluster Galaxy Cluster Member High Redshift Cluster Core Distant Cluster
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- Bíngellí, B., Tammann, G. A., and Sandage, A. 1987 ESO preprint no. 498.Google Scholar
- Ap. J. ,226, 559.Google Scholar
- Ap. J. ,285, 426.Google Scholar
- Nature ,310, 31.Google Scholar
- De Lapparent, V., Geller, M. J., and Huchra, J. 1986 Ap. J. (Lett), 302, LI.Google Scholar
- Dressier, A. 1987 in Nearly Normal Galaxies: From the Planck Time to the Present ,ed. S. M. Faber (Springer-Verlag, New York) p. 276.Google Scholar
- 1983 Ap. J. ,270, 7.Google Scholar
- Ellis, R. S. 1987 in IAU Symp. No. 124, Observational Cosmology, ed. A. Hewitt, G. Burbidge, and L. Z. Fang (Reidel, Dordrecht) p. 367.Google Scholar
- Gunn, J. E. 1987 in Nearly Normal Galaxies: From the Planck Time to the Present ,ed. S. M. Faber (New York:Springer-Verlag) p. 455.Google Scholar
- Huchra, J. 1988 in IAU Symp. No. 130, Evolution of Large Scale Structures in the Universe ,in press.Google Scholar
- 1986 Ap.J. ,311, 651.Google Scholar
- MacLaren, I., Ellis, R. S., and Couch, W. J. 1987 MNRAS, in press.Google Scholar