NONLINEAR EVOLUTION OF COSMIC BARYON FLUID

Abstract

Although the gravitational field in the universe is dominated by dark matter, observations show that the statistical properties of cosmic baryonic 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. This scenario provides a coherent explanation of various phenomena referring to the decoupling of the IGM from dark matter, including the log-Poisson non-Gaussianity of Ly-alpha transmitted flux fluctuations; turbulent broadening; abnormal scaling; baryon missing in halos etc.