Coalescence of self-gravitating gaseous masses - A numerical model

A criterion of coalescence for self-gravitating gaseous masses of galactic scale with primeval chemical composition and radiative cooling is found using a two-dimensional numerical gas-dynamical model of the non-central supersonic collision of masses. The results of a series of computations are presented for a wide range of impact parameters and relative velocities of collision. It is shown that coalescence can lead to the formation of a gaseous protogalaxy with a considerable amount of angular momentum. The authors discuss briefly an evolutionary scenario for separation within the collapsing and fragmentating protogalaxy of two dynamical subsystems - a rapidly rotating disc and a slowly rotating halo.