Models of Galaxy Clusters with Thermal Conduction

We present a simple model of hot gas in galaxy clusters, assuming hydrostaticequilibrium and energy balance between radiative cooling and thermalconduction. For five clusters, A1795, A1835, A2199, A2390 and RXJ1347.5-1145,the model gives a good description of the observed radial profiles of electrondensity and temperature, provided we take the thermal conductivity $\kappa$ tobe about 30% of the Spitzer conductivity. Since the required $\kappa$ isconsistent with the recent theoretical estimate of Narayan & Medvedev (2001)for a turbulent magnetized plasma, we consider a conduction-based equilibriummodel to be viable for these clusters. We further show that the hot gas isthermally stable because of the presence of conduction. For five otherclusters, A2052, A2597, Hydra A, Ser 159-03 and 3C295, the model requiresunphysically large values of $\kappa$ to fit the data. These clusters must havesome additional source of heat, most likely an active galactic nucleus sinceall the clusters have strong radio galaxies at their centers. We suggest thatthermal conduction, though not dominant in these clusters, may neverthelessplay a significant role by preventing the gas from becoming thermally unstable.Comment: Published in ApJ; 22 pages, including 2 tables, 4 figures; typos corrected to match the published versio