Quantifying the effect of cooled initial conditions on cosmic string
  network evolution
  Quantitative studies of the evolution and cosmological consequences of
networks of cosmic strings (or other topological defects) require a combination
of numerical simulations and analytic modeling with the velocity-dependent
one-scale (VOS) model. In previous work, we demonstrated that a GPU-accelerated
code for local Abelian-Higgs string networks enables a statistical separation
of key dynamical processes affecting the evolution of the string networks and
thus a precise calibration of the VOS model. Here we further exploit this code
in a detailed study of two important aspects connecting the simulations with
the VOS model. First, we study the sensitivity of the model calibration to the
presence (or absence) of thermal oscillations due to high gradients in the
initial conditions. This is relevant since in some Abelian-Higgs simulations
described in the literature a period of artificial (unphysical)
dissipation---usually known as cooling---is introduced with the goal of
suppressing these oscillations and accelerating the convergence to scaling. We
show that a small amount of cooling has no statistically significant impact on
the VOS model calibration, while a longer dissipation period does have a
noticeable effect. Second, in doing this analysis we also introduce an improved
Markov Chain Monte Carlo based pipeline for calibrating the VOS model,
Comparison to our previous bootstrap based pipeline shows that the latter
accurately determined the best-fit values of the VOS model parameter, but
underestimated the uncertainties in some of the parameters. Overall, our
analysis shows that the calibration pipeline is robust and can be applied to
future much larger field theory simulations.
