Three-dimensional hydrodynamical modeling of accretion-disk formation in microquasars. Cen X-3

We have carried out three-dimensional hydrodynamical modeling of the formation of an accretion disk around a compact object due to radiative wind of a massive donor in a close binary system. The massive X-ray binary Cen X-3, which has a precessing accretion disk and may possess relativistic jets, is considered as an example. The computations show that, when the action of the central compact object on the formation of the wind is taken into account, the radiative wind forms an accretion disk with a radius of 0.16 (in units of the orbital separation), which accretes at a rate close to 1 x 10(-8) M-./yr. In this model, the disk is spherically symmetrical and geometrically thick, with a tunnel going from the accretor to the upper layers of the disk along the accretor's rotational axis at the disk center. The number density of the gas in the tunnel is five orders of magnitude lower than in the disk. The wind-disk interaction at the outer boundary of the disk produces a strong shock (wind-disk shock) directed toward the donor. The black-body emission of the disk and tunnel is nonstationary, and resembles the outbursts observed in Cen X-3. An analysis of the location of the region of nonstationary emission suggests that the outbursts occur in the wind-disk shock.