Metastable cosmic strings produce a gravitational wave background that is best modeled with three parameters (string tension Gμ plus independent time scales t_LB and t_NC), yielding a compact analytical spectrum when t_LB greatly exceeds t_NC.
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Stochastic gravitational wave background from smoothed cosmic string loops
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abstract
We do a complete calculation of the stochastic gravitational wave background to be expected from cosmic strings. We start from a population of string loops taken from simulations, smooth these by Lorentzian convolution as a model of gravitational back reaction, calculate the average spectrum of gravitational waves emitted by the string population at any given time, and propagate it through a standard model cosmology to find the stochastic background today. We take into account all known effects, including changes in the number of cosmological relativistic degrees of freedom at early times and the possibility that some energy is in rare bursts that we might never have observed.
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