Goldstone bosons in string models of galaxy formation

One reason why cosmic strings are interesting is because they may provide the primordial density fluctuations that began the process of galaxy formation. For the scenario in which galaxies condense around oscillating closed loops it is necessary that gravitational radiation be the dominant energy-loss mechanism. It is shown that loops of strings from a broken exact global symmetry decay too quickly to serve this purpose. Loops of strings from a broken gauge symmetry may have Goldstone-boson couplings as well. It is shown that the decay rate of these strings due to Goldstone-boson emission is strongly suppressed. This supports the conjecture that gauge strings may seed galaxy formation.