MAGNETIC-FIELDS AND LARGE-SCALE STRUCTURE IN A HOT UNIVERSE .2. MAGNETIC-FLUX TUBES AND FILAMENTARY STRUCTURE

In Paper I, we obtained an equation for the evolution of density inhom ogeneities in a radiation dominated universe when they are affected by magnetic fields. In this second paper we apply this equation to the c ase in which the subjacent magnetic configuration is a flux tube. For scales of the order of 1 Mpc or less the differential equation is elli ptical. To solve it, we have used the numerical method based on ''Simu ltaneous Over Relaxation'', SOR, with Chebyshev acceleration and we ha ve treated the problem as a boundary value problem, which restricts th e prediction ability of the integration. For large-scale flux tubes, m uch larger than 1 Mpc, the equation can be analytically integrated and no assumption about the final shape or magnitude of the inhomogeneity is required. In both cases we obtain an evolution which does not diff er very much from linear in time. The inhomogeneity in the density bec omes filamentary. Large scale structures (greater than or equal to 10 Mpc) are probably unaffected by damping, non-linear and amplification mechanisms after Equality, so that this model provides a tool to inter pret the present observed large scale structure. Filaments are very fr equently found in the large-scale structure in the Universe. It is sug gested here that they could arise from primordial magnetic flux tubes, thus providing an alternative hypothesis for its interpretation; in p articular we consider the case of the Coma-A1367 supercluster, where t he magnetic field is known to be high.