Prospects for SODART observations of nearby clusters of galaxies

Using the current best understanding of the SODART mirror system, the Bragg panel and of the LEPC/HEPC responses [1] we have studied the feasibility and prospects for SODART studies of nearby clusters of galaxies. From simulated HEPC data of the cluster Abell 2256, we demonstrate that SODART observations of the hot intergalactic gas in nearby clusters offer an opportunity for efficient mapping of the hot gas temperature structure ail the way to the virial radius. The temperature map is a good diagnostic of the dynamical state of a cluster and for relaxed clusters the temperature profile derived from HEPC data allows a straight forward determination of the cluster mass profile with a formal accuracy comparable to the effects of systematics. As a case study for assessing the feasibility of Bragg panel observations of clusters we have simulated observations of the Perseus cluster core with the UF and RAP crystals. Using the LIF crystals, it is possible to scan each of the Fe-K lines from the hot gas in a few 30 ks exposures enabling possible detection of turbulence and/or bulk flow of the hot gas. Substantially longer exposures are required with the RAP crystals for studying lines originating in cool gas, but the line strengths are heavily dependent on the temperature of the cool gas. Hence, for the Perseus cluster, and perhaps a handful of other clusters, the unique capabilities of the Bragg panel for spectre-imaging of extended sources provide direct insight into the plasma processes in the gas.