Gas and Dark Matter Spherical Dynamics

摘要

We investigate the formation of spherical cosmological structures following both dark matter and gas components. We focus on the dynamical aspect of the collapse assuming an adiabatic, γ= 5/3, fully ionized primordial plasma. We use for that purpose a fully Lagrangian hydrodynamical code designed to describe highly compressible flows in spherical geometry. We investigate also a "fluid approach" to describe the mean physical quantities of the dark matter flow. We test its validity for a wide range of initial density contrast. We show that a homogeneous isentropic core forms in the gas distribution, sur- rounded by a self-similar hydrostatic halo, with much higher entropy generated by shock dissipation.