AAS 205th Meeting, 9-13 January 2005
Session 147 Groups and Clusters of Galaxies
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[147.17] AGN heating and convection in galaxy-cluster plasmas

B. D. G. Chandran (University of Iowa)

Heating of intracluster plasma is the key to solving the cooling-flow problem and explaining the star-formation histories and intracluster plasma profiles of galaxy clusters. This poster describes a model for AGN heating of galaxy-cluster plasmas that relies upon the turbulent heating associated with convection driven by the buoyancy of centrally produced cosmic rays. The cosmic-ray luminosity is powered by Bondi accretion of intracluster plasma onto a central supermassive black hole. A two-fluid mixing-length theory is developed to treat convection in the thermal-plasma/cosmic-ray fluid. The model equations are solved to obtain equilibrium profiles of the density, temperature, rms turbulent velocity, and cosmic-ray pressure. Although the intracluster medium is convectively unstable near cluster center in the model solutions, the specific entropy of the thermal plasma still increases outwards because of the cosmic-ray modification to the stability criterion. This work was supported by NSF grant AST-0098086 and DOE grants DE-FG02-01ER54658 and DE-FC02-01ER54651 at the University of Iowa.

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