Different Methods of Forming Cold Fronts in Galaxy Clusters and Their impact on the Dynamics of the Intracluster Gas

One of the most interesting features discovered by Chandra satellite observations of galaxy clusters are the sharp X-ray surface brightness discontinuities, accompanied by jumps in gas temperature named “cold fronts”. The temperature and density jumps happen in such a way as to maintain the gas pressure continuously across the front and, therefore, they are not created by shocks. They were originally interpreted as being the result of subsonic (transonic) motions of head-on merging substructures with suppressed thermal conduction, which are theoretically justified especially for clusters that have clear signs of merging, such as the “bullet cluster” 1E0657-56. However, these models do not work well for the increasing number of cold fronts (sometimes multiple cold fronts in the same cluster) found in apparently non-merging clusters which prompted the development of other models for cold front generation, such as oscillation of the cD and the low entropy gas around the bottom of the potential well, hydrodynamic gas sloshing, or dark matter peak oscillation due to scattering of a smaller dark matter system. Here, I will present recent evidence pro and against these different mechanisms and their impact on the dynamics of the intracluster gas.

 

Date: 
25/01/2007 - 13:00
Speaker: 
Renato Dupke
Filiation: 
Univ. Michigan, Ann Arbor


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