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S. M. O'Neill (U. Minnesota), I. L. Tregillis (Los Alamos National Laboratory), T. W. Jones (U. Minnesota), D. Ryu (Chungnam National University, Korea)
We present a set of high-resolution 3D MHD simulations of steady light, supersonic jets, exploring the influence of jet Mach number and the structure of the ambient medium on jet propagation and energy transport over long distances. Specifically, we simulated the propagation of light jets with internal Mach numbers 3 and 12 (external Mach numbers 30 and 120) to lengths exceeding 100 initial jet radii in both uniform and "King-type" stratified atmospheres.
The propagating jets asymptotically deposit slightly less than half of their energy flux as thermal energy in the ambient atmosphere, almost independent of jet Mach number or the external density gradient. A similar energy fraction remains within the boundaries of the jet cocoon, with a smaller amount resident at a given time in ambient medium kinetic energy. Since jets propagate more rapidly down a density gradient, the total energy available is considerably less in that case for a given jet length. The high efficiency of thermal energy deposition into the ambient medium by the jets supports suggestions that AGNs are effective feedback sources in cluster media.
We also find that simple self-similar scaling relations accurately represent the time evolution of jet length and flow morphology. This suggests that simple models can be applied to provide physically reasonable estimates of energy densities in observed systems without a detailed knowledge of their evolutionary history.
This work is supported by the NSF and the University of Minnesota Supercomputing Institute.
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The author(s) of this abstract have provided an email address for comments about the abstract: soneill@astro.umn.edu
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.