FORMATION OF THE FIRST OBJECTS AND GALAXIES IN THE LONG COSMIC-STRINGSCHEME

The formation of wakes is triggered by the passing of long cosmic stri ngs, and the high-density nonlinear sites of cold dark matter are expe cted to form at each crossing point of three wakes. We investigate the dark matter potential of such crossing points of three wakes, trigger ed at redshift z(i), in the approximation of spherical symmetry. We de rive for several values of z(i) the characteristic values of the dark matter potential, such as the radius, mass, and density distribution, at 1 + z = 10(2), 10, and 1, respectively. Then we calculate the motio n of baryonic matter in this potential, taking into account the drag f orce due to the background radiation and the thermal processes such as ionization degree and H-2 molecular cooling. The first objects are fo rmed at z similar to 300-200 because of the Jeans instability in the h igh-density region developed around the crossing points of three wakes triggered at z(i) similar to 10(4)-10(5). The mass and size of these objects are of the order of 10(3) M. and 10(-1) pc. For wakes triggere d at z(i) similar or equal to 10(6) and 10(7), objects are formed at z similar to 70 and 5, respectively, and their mass and size are of the order of 10(3) M. and 1 pc, respectively. The infall of baryonic matt er to these objects in later time is also investigated to simulate gal axy formation and compared with the observations. Although the details of the stellar formation process must be much pursued, the results in the adopted assumption seem to be in good agreement with the observat ions of E-type galaxies. The formation of other astronomical objects i s also discussed.