Accurate Realizations of the Ionized Gas in Galaxy Clusters: Calibrating Feedback

Using the full, three-dimensional potential of galaxy cluster halos (drawnfrom an N-body simulation of the current, most favored cosmology), thedistribution of the X-ray emitting gas is found by assuming a polytropicequation of state and hydrostatic equilibrium, with constraints fromconservation of energy and pressure balance at the cluster boundary. Theresulting properties of the gas for these simulated redshift zero clusters (thetemperature distribution, mass-temperature and luminosity-temperaturerelations, and the gas fraction) are compared with observations in the X-ray ofnearby clusters. The observed properties are reproduced only under theassumption that substantial energy injection from non-gravitational sources hasoccurred. Our model does not specify the source, but star formation and AGN maybe capable of providing this energy, which amounts to 3 to 5 x10^{-5} of therest mass in stars (assuming ten percent of the gas initially in the clusterforms stars). With the method described here it is possible to generaterealistic X-ray and Sunyaev-Zel'dovich cluster maps and catalogs from N-bodysimulations, with the distributions of internal halo properties (and theirtrends with mass, location, and time) taken into account.Comment: Matches ApJ published version; 30 pages, 7 figure