Evolution of cosmic string networks

Andreas Albrecht NASA/ Fermilab Astrophysics Center Fermi National Accelerator Laboratory Batavia, IL 60510 and Neil Turok Joseph Henry Laboratories Princeton University Princeton, N J 08544 Abstract A discussion of the evolution and observable consequences of a network of cosmic strings is given. A simple model for the evolution of the string network is presented, and related to the statistical mechanics of string networks. The model predicts the long string density throughout the history of the universe from a single parameter, which we calculate in radiation era simulations, The statistical mechanics arguments indicate a particular 'thermal' form for the spectrum of loops chopped off the network. Detailed numerical simulations of string networks in expanding backgrounds are performed to test the model. Consequences for large scale structure, the microwave and gravity wave backgrounds, nucleosynthesis and gravitational lensing are calculated.