ACCRETION OF HOT DARK MATTER ONTO SLOWLY MOVING COSMIC STRINGS

Cosmic strings with small-scale structure have a coarse-grained mass per unit length μ which is larger than the string tension. This leads to an effective Newtonian gravitational line source and to a characteristic translational velocity which is smaller than for strings without small-scale structure. Here, the accretion of hot dark matter onto such strings is studied by means of the Zel’dovich approximation. We find that clustering is greatly enhanced by the Newtonian line source. In the limit of vanishing translational velocity, the first nonlinear filaments form at a redshift of greater than 100 for standard values of μ.