Wednesday, December 17, 2008 - 3:15pm
"Simulations of AGN feedback in galaxy clusters and groups"
Abstract. Understanding galaxy cluster properties is essential for exploiting the full potential of clusters as cosmological probes. Recently, observational and theoretical progress has established that AGN play a decisive role in the formation and evolution of galaxy groups and clusters. Here we use high-resolution cosmological simulations of a large cluster and group sample to study how AGN affect their host systems, and modify cluster scaling relations. More specifically, we use a new technique to self-consistently follow the growth of black holes and include associated feedback processes in hydrodynamical simulations. This allows us to investigate the effect of AGN in detail. We show that AGN feedback can indeed solve several problems that previous generations of hydrodynamical cluster simulations without black hole physics had. Namely, AGN feedback prevents overcooling in cluster cores, thereby yielding much more realistic masses of central galaxies, and allows us to accurately reproduce the observed X-ray luminosity-temperature scaling relation at all mass scales from massive clusters to small groups. Furthermore it reduces the halo gas fractions in small systems, bringing them in excellent agreement with observations. This new technique considerably brightens the prospects to use simulations of cluster formation to accurately calibrate and correct systematic effects in future X-ray and Sunyaev-Zel'dovich cluster surveys, which aim to accurately constrain the expansion history of the Universe.