February 4, 1999 CfA Colloquium

Title: A Study of Nine High-Redshift Clusters of Galaxies: Properties of their Galaxy Populations and Implications for Galaxy Evolution

Speaker: Lori M. Lubin

Abstract: The first results of an extensive photometric, spectroscopic, and morphological study of nine cluster candidates at redshifts of z > 0.6 will be presented. I will discuss the properties of three massive clusters at redshifts between z = 0.75 and z = 0.92. Specifically, I will focus on the spectral and photometric characteristics of the member galaxies. The results at high redshift will be compared to previous studies of nearby clusters and those found at intermediate redshifts. In addition to massive clusters, this survey is being used to study smaller systems of galaxies at these redshifts. In particular, I will discuss one system at z = 0.84 which consists of two galaxy groups which are close both in radial velocity and in position on the sky. This group-group system may currently be merging into a larger cluster of galaxies. The nature of this system and other groups at high redshift may have important implications for cluster formation and galaxy evolution.

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