Galaxy pairs and clusters in a lambda CDM universe: Bridging observation and simulation

Berrier, Joel Craig
Bibliographical reference

Proquest Dissertations And Theses 2008. Section 0030, Part 0606 135 pages; [Ph.D. dissertation].United States -- California: University of California, Irvine; 2008. Publication Number: AAT 3328054. Source: DAI-B 69/09, Mar 2009

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I use computer simulations to examine the evolution of close galaxy pair counts and the formation of galaxy clusters. I show that the evolution of the close pair fraction is much weaker than the strong evolution in the dark matter halo merger rate. I continue with a discussion of how galaxy cluster-sized dark matter halos are assembled. This result, contrary to some expectations, shows that galaxy clusters in simulations are built from field halos instead of groups. I conclude by presenting preliminary results of a method to determine the pair fraction of galaxies at z=3 and apply it to a spectroscopic sample of LBGs. I show that the pair fraction is a factor of ~ 4 higher at z ~ 3 compared to local galaxy samples with similar number densities.