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A. R. Marble, J. O. Burns (University of Missouri-Columbia), C. Loken (St. Mary's University-Halifax N.S.), K. Roettiger (University of Missouri-Columbia)
Galaxy clusters are now believed to be dynamic systems which formed relatively recently. Those that have not yet reached a relaxed state exhibit morphological substructure in the x-ray emission of their intergalactic gas. The overall degree of this substructure is taken to be an indication of the epoch of cluster formation. This allows us to further constrain cosmological models which describe the evolution of galaxy clusters. We present the results of substructure analysis on a statistically complete, flux-limited sample of Abell clusters and numerically evolved clusters from high-resolution, gas+N-body cosmological simulations of a \LambdaCDM universe. Our sample is composed of ROSAT PSPC observations as well as observations taken from the ROSAT All Sky Survey. The degree of substructure in a given cluster is determined with regard to changes in the centroid positions, ellipticities, and position angles of ellipses fitted to the inner and outer regions of the x-ray emission. This work is supported by the Missouri Space Grant Consortium.