Author: Fulai GuoPublisher:
ISBN: 9780549848424
Category :
Languages : en
Pages : 254
Book Description
Recent observations show that the cooling flows in the central regions of galaxy clusters are highly suppressed. Observed active galactic nucleus (AGN)-induced cavities/bubbles are a leading candidate for suppressing cooling. Motivated by observational signatures of a non-thermal particle population in these bubbles and the surrounding intracluster medium (ICM), we first propose a new model of AGN heating, in which the ICM is efficiently heated by cosmic-rays, which are injected into the ICM through diffusion or the shredding of the bubbles by Rayleigh-Taylor or Kelvin-Helmholtz instabilities. We include thermal conduction as well. Using numerical simulations, we show that the cooling catastrophe is efficiently suppressed. The cluster quickly relaxes to a quasi-equilibrium state with a highly reduced accretion rate and temperature and density profiles which match observations. Unlike the conduction-only case, no fine-tuning of the Spitzer conduction suppression factor f is needed. The cosmic ray pressure Pc/Pg & lsim;0.1 and1Pc & lsim;0. 1rg is well within observational bounds.
