AAS 205th Meeting, 9-13 January 2005
Session 75 Galaxy Clusters and Groups I
Oral, Tuesday, January 11, 2005, 10:00-11:30am, Pacific 2/3

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[75.03] Discovering Shocks in the Intracluster Medium: Cosmological Simulations and Synthetic X-ray Observations of Clusters/Groups

E. J. Hallman (University of Colorado), Dongsu Ryu (Chungnam National University), Hyesung Kang (Busan National University), T.W. Jones (University of Minnesota)

The results of a study of X-ray substructure indicative of flow discontinuities in the intracluster gas are presented. We present high-resolution N-body/hydro cosmological simulations of a \LambdaCDM universe and synthetic X-ray observations of the resulting galaxy clusters/groups. The simulations show a complex web of shock structures in the intracluster medium of most clusters/groups, of which only a small fraction appear to be detected in X-ray observations of real clusters. These shocks result from supersonic flows generated during the process of accretion in large-scale structure, and serve as unique diagnostics of the dynamical state of the gas, and as tracers of the evolution of structure formation. A blind search for shocks in our synthetic X-ray images is performed to confirm the observational interpretation of X-ray features which presumably result from the presence of shocks and contact discontinuities. We show that the distribution of shocks in simulated cluster volumes can be reliably deduced using synthetic X-ray observations. A preliminary identification scheme for cold fronts in the synthetic observations shows that they have a similar distribution as a function of the steepness of the temperature jump as do shocks. We suggest observational strategies for identifying and classifying shocks and cold fronts. We find that the careful selection of X-ray energy bands for observation increases the probability of finding shocks. We also show that the X-ray emission character of gas in clusters/groups with Tx\leq 3 keV makes them excellent candidates for observational shock detection. This work is supported by the NSF and the Minnesota Supercomputing Institute.

The author(s) of this abstract have provided an email address for comments about the abstract: eric.hallman@colorado.edu

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.