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