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Session 53 - The X Clusters: Cooling Flows.
Display session, Thursday, January 08
The cluster Abell 2597 is one of the nearest strong cooling-flow clusters, and possesses remarkable ``blue lobes'' associated with the emission-line nebula in the centre of the cluster, and co-incident with the radio lobes of the central radio source. This object therefore represents a good case-study for investigating the detailed physical processes involved in the interactions between the hot Intra-Cluster Medium (ICM), the cooler 10^4\,K gas and the radio plasma associated with the central radio source. Previous studies have shown that popular ionization models, including photoionization and auto-ionizing shocks, may be insufficient to fully describe the properties of the emission-line nebula, thus highlighting a possible need for an additional energy input source. We address this question by presenting detailed HST WF/PC-2 broad-band and narrow-band images of the nebula and the central galaxy, and combine these with high S/N radio images and X-ray data to discuss the interplay between the expanding radio lobes, the ICM and the emission-line gas. In particular, we investigate various possibilities for the additional energy supply to the emission-line nebula, including direct thermal energy input from the surrounding ICM, or from the lobes of the radio source. The reciprocal effect of the surrounding gas upon the evolution of the radio source is also discussed, together with the overall role played by the radio source in the long-term energetics of the cooling-flow nebula.
Program listing for Thursday