Formation of the First Objects and Galaxies in the Long Cosmic String Scheme

The formation of wakes is triggered by the passing of long cosmic strings, and the high-density nonlinear sites of cold dark matter are expected to form at each crossing point of three wakes. We investigate the dark matter potential of such crossing points of three wakes, triggered at redshift zᵢ_, in the approximation of spherical Symmetry. We derive for several values of zᵢ_ the characteristic values of the dark matter potential, such as the radius, mass, and density distribution, at 1 + z = 10²^, 10, and 1, respectively. Then we calculate the motion of baryonic matter in this potential, taking into account the drag force due to the background radiation and the thermal processes such as ionization degree and H₂_ molecular cooling. The first objects are formed at z ~ 300-200 because of the Jeans instability in the high-density region developed around the crossing points of three wakes triggered at zᵢ_ ~ 10⁴^-10⁵^. The mass and size of these objects are of the order of 10³^ Mₛun_ and 10^-1^ pc. For wakes triggered at zᵢ_ ~ 10⁶^ and 10⁷^, objects are formed at z ~ 70 and 5, respectively, and their mass and size are of the order of 10³^ Mₛun_ and 1 pc, respectively. The infall of baryonic matter to these objects in later time is also investigated to simulate galaxy 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 observations of E-type galaxies. The formation of other astronomical objects is also discussed.