Cosmic Strings and Structure Formation

We discuss structure formation in cosmic string theories. Emphasis is laid on the properties of the peculiar velocity field, non–gaussian features and clusters of galaxies. It is found that the predicted peculiar velocity field is quiet (v < 150 km/s for L > 30h Mpc) for models with (Ω0h ≤ 0.2) which is in disagreement with the results from POTENT at large scales (> 30h Mpc), consistent, however, with the analysis of the peculiar velocity field of spiral galaxies by Giovannelli et al. [16]. Using the Press–Schechter formalism we calculate the abundances of X–ray clusters. It is found that in CDM models a mass fluctuation σ8 = 0.6...0.7 is needed with Ω0h = 0.1...0.2 in order to explain the current data.