8th HEAD Meeting, 8-11 September, 2004
Session 2 Galaxy Clusters and the Intergalactic Medium
Poster, Wednesday, September 8, 2004, 9:00am-10:00pm

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[2.21] Effects of Mergers on the Structure of Galaxy Clusters

T. B. O'Hara, J. J. Mohr (University of Illinois)

Evidence for merging is found in a large fraction of the galaxy cluster population, yet clusters exhibit remarkable regularity in their bulk property scaling relations. This fact is rendered more striking by the suggestion by some simulations that merging clusters should undergo large boosts to properties such as X-ray luminosity and temperature. Since such properties will be used as proxies for cluster mass in surveys using galaxy clusters to study the dark energy, undetected merger-related boosts could result in errors in measurements of cosmological parameters.

The goal of this work is to examine the relationship between merger signatures and the positions of clusters on scaling relations. We present here results of a study using a sample of 45 clusters observed with ROSAT and an ensemble of hydrodynamic simulations. We examine the correlation between quantitative measures of cluster geometry and deviations from X-ray and near-infrared scaling relations. We seek to characterize the intrinsic scatter of clusters about these relations. With this information we attempt to identify the processes that lead to the extreme regularity of scaling relations, and to determine whether merging clusters indeed undergo bulk property shifts that would result in incorrect measurements of their masses.

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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.