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T. W. Jones (University of Minnesota), D. S. DeYoung (NOAO)
We report on an extensive set of 2D MHD simulations of hot, buoyant bubbles evolving in a realistic intracluster medium. Our bubbles are inflated near the base of the ICM over a finite time from a region that is magnetically isolated from the ICM. We confirm earlier work based on linear analytic analyses and simulations of preformed bubbles that very modest magnetic fields can stabilize the rising bubbles against disruption by Raleigh-Taylor and Kelvin-Helmholtz instabilities. We find, in addition, that amplification of the ambient and internal fields during the early bubble evolution can be sufficient to protect the bubbles or their early fragments even if the fields are initially too weak to play a significant role in the beginning. Indeed, even with initial fields less than a micro-Gauss and values of beta = Pg/Pb approaching 105, magnetic stresses in our simulations eventually became large enough to influence bubble evolution. Magnetic field influence also depends on the geometry of the ICM field and on the topology of the total field at the bubble/ICM interface. These calculations also show that lifting and mixing of the ambient ICM may be a critical function of field geometries in both the ICM and the bubble interior.
This work was supported at the University of Minnesota by the NSF and by the University of Minnesota Supercomputing Institute. NOAO is operated by AURA, Inc under contract to the NSF.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.