Three-dimensional modeling of the evolution of protogalaxies - Rapidly rotating objects

Results of a 3D simulation of the collapse and evolution of isolated protogalaxy perturbation with initial spin parameter lambda of about 0.08 are presented. Initial perturbation was taken as a homogeneous rigidly rotating spherical object involved in the Hubble flow and made of dark and baryonic matter in a 10:1 ratio. The total mass of the baryonic component was 10 exp 11 solar masses, and the initial radius of the protogalaxy was 100 kpc. The dynamics of the gaseous component was described by means of smoothed particle hydrodynamics, and that of the dark matter by the N-body algorithm. The model includes the processes of star formation, the energy and matter feedback due to supernova events, the presence of chaotic motions, and the time lag between the initial development of suitable conditions for star formation and star formation itself. It is shown that over cosmological time-scales, protogalaxy perturbation having high lambda forms a typical spiral galaxy. Its rotation curve, star formation rate, gravitational potential, and surface density distribution are similar to those of our Galaxy.