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Stochastic gravitational wave background generated by cosmic string networks: Velocity-dependent one-scale model versus scale-invariant evolution

L. Sousa, P. P. Avelino

We compute the power spectrum of the stochastic gravitational wave background generated by cosmic string networks, described by the velocity-dependent one-scale (VOS) model for a wide range of macroscopic and microscopic parameters. The VOS model—which has been shown to provide an accurate macroscopic description of the evolution of cosmic string networks—is used to demonstrate that cosmic string networks are unable to rapidly attain scale-invariant evolution after the transition between the radiation and matter eras. However, in computations of the stochastic gravitational wave background, it is often assumed that the networks experience scale-invariant evolution throughout cosmological history. We demonstrate that this assumption leads to an underestimation of the amplitude and broadness of the peak of the spectrum. As a result, the total energy density of gravitational waves at the present day obtained using the VOS model may be up to 70% larger than that obtained under the linear scaling assumption.

Physical Review D
Volume 88, Issue 2
2013 July

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia