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The Ohio State University
College of Mathematical & Physical Sciences
Department of Astronomy Colloquium Series 2006/7
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Friday, November 17, 12:30 p.m.
2015 McPherson Laboratory
The Evolution of Large-Scale Structure:
Clusters and Groups of Galaxies
Tesla Jeltema
Carnegie Observatories
Large-scale structure has long been known to encode basic information
about our universe. It is increasingly becoming apparent that environment
and the evolution of environment play a key role in the properties of
structure on all scales. I will discuss the evolution of structure on two
scales: massive clusters of galaxies and the more common groups of
galaxies. First, I will describe a study of the frequency of cluster
mergers versus time by quantifying the amount of substructure in clusters
versus redshift. We find that, as expected qualitatively in hierarchical
models of structure formation, the amount of substructure in clusters
increases with redshift. This systematic trend of cluster
dynamical state with time has important implications for cosmological
studies with clusters. Second, I will discuss a multiwavelength study of
intermediate-redshift groups of galaxies. Groups are the most common
environment for galaxies in the universe making them important sites for
studies of galaxy evolution. Groups are also important to the
understanding of the non-gravitational processes which may affect the
intercluster medium. However, their low galaxy densities and faint X-ray
emission make groups difficult to recognize at even moderate redshifts,
and studies of representative samples of groups at z>0.1 are just
beginning.
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Modified 2006 Nov 13 [rwp]