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Physics and Astronomy

Physics & Astronomy Colloquium

3:30 PM, Friday, November 11, 2011
Room 155, Chem-Phys Building

Dr. Li-Zhi Fang
Department of Physics
University of Arizona

"Statistical and Dynamical Decoupling of the IGM from Dark Matter''

Although the gravitational field in the universe is dominated by dark matter, observations show that the the velocity and density fields of cosmic baryon matter are significantly and systematically decoupled from that of the underlying dark matter. This is because the cosmic baryon fluid in highly nonlinear regime is in a state of fully developed turbulence, of which the velocity field consists of shocks, vortices and complex structures. The dynamics of vorticity of turbulent fluid is independent of gravity and can be self maintained by the nonlinearity of hydrodynamics. This scenario provides a coherent explanation of various phenomena referring to the decoupling of the IGM from dark matter, including the baryon missing in halos; offset between dark and baryon matter; log-Poisson non-Gaussianity of Ly-alpha transmitted flux fluctuations; turbulent broadening; abnormal scaling; baryon missing in halos etc. A further test on the turbulence scenario will be given by the CMB fluctuations on angular scales of arc-minutes.

Refreshments will be served in CP 179 at 3:15 PM