X-ray and SZ Signatures of The Non-Equipartition Between Electrons and Ions in The Envelopes of Relaxed Galaxy Clusters

Ka-Wah Wong, Minnesota State University Mankato
Craig L. Sarazin, University of Virginia


The study of cosmology using clusters of galaxies relies heavily on the understanding of cluster physics. For precision cosmology, systematic uncertainties at even the percent level are significant. In fact, the physical state of the hot gas in outskirts of clusters is poorly known. Electrons and ions in the intracluster medium are usually assumed to be in equipartition. However, in cluster outer regions, such an assumption is questionable due to the extreme low density and hence the long electron-ion equilibration time scale. Using one-dimensional hydrodynamic simulations, we have studied the non-equipartition effects in the outer regions of relaxed clusters under the ΛCDM cosmology. X-ray and SZ signatures of the non-equipartition electrons and ions will be presented. Possible implications to the precision cosmological studies will be discussed.