The Stochastic Gravitational Wave Background Generated by Cosmic String   Networks: the Small-Loop Regime
  We consider an alternative approach for the computation of the stochastic gravitational wave background generated by small loops produced throughout the cosmological evolution of cosmic string networks and use it to derive an analytical approximation to the corresponding power spectrum. We show that this approximation produces an excellent fit to more elaborate results obtained using the Velocity-dependent One-Scale model to describe cosmic string network dynamics, over a wide frequency range, in the small-loop regime. 
L. Sousa and P. P. Avelino
astro-ph.CO