Extending and Calibrating the Velocity dependent One-Scale model for
  Cosmic Strings with One Thousand Field Theory Simulations
  Understanding the evolution and cosmological consequences of topological
defect networks requires a combination of analytic modeling and numerical
simulations. The canonical analytic model for defect network evolution is the
Velocity-dependent One-Scale (VOS) model. For the case of cosmic strings, this
has so far been calibrated using small numbers of Goto-Nambu and field theory
simulations, in the radiation and matter eras, as well as in Minkowski
spacetime. But the model is only as good as the available simulations, and it
should be extended as further simulations become available. In previous work we
presented a General Purpose Graphics Processing Unit implementation of the
evolution of cosmological domain wall networks, and used it to obtain an
improved VOS model for domain walls. Here we continue this effort, exploiting a
more recent analogous code for local Abelian-Higgs string networks. The
significant gains in speed afforded by this code enabled us to carry out 1032
field theory simulations of $512^3$ size, with 43 different expansion rates.
This detailed exploration of the effects of the expansion rate on the network
properties in turn enables a statistical separation of various dynamical
processes affecting the evolution of the network. We thus extend and accurately
calibrate the VOS model for cosmic strings, including separate terms for energy
losses due to loop production and scalar/gauge radiation. By comparing this
newly calibrated VOS model with the analogous one for domain walls we
quantitatively show that energy loss mechanisms are different for the two types
of defects.
