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Session 116 - Galaxy Clusters & Evolution.
Oral session, Saturday, January 10

[116.04] An Deficiency of High Redshift, High Luminosity X-ray Clusters: Evidence for a High Value for Omega.

R. C. Nichol (CMU), D. Reichart (U. Chicago), A. K. Romer (CMU), C. A. Collins, D. J. Burke (LJMU), B. P. Holden, M. P. Ulmer (NWU)

There have been several recent analyses of clusters taken from the EMSS sample (Henry et al 1997) that have yielded yield low values (Omega_0<0.3) for the cosmic density (Donahue et al 1997, Carlberg et al 1997). By contrast, the results from a new analysis - which takes full account of the evolution in the luminosity temperature relationship - supports values of Omega_0 close to unity. We present our method and its application to two flux limited samples of high redshift clusters; the revised EMSS sample from Nichol et al (1997) and the SHARC South sample of Burke et al (1997). We go on to discuss possible systematic errors in our method and in the two cluster samples that might be mimicing a high value of Omega.

Program listing for Saturday