Quantifying the effect of cooled initial conditions on cosmic string network evolution
Abstract
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 velocitydependent onescale (VOS) model. In previous work, we demonstrated that a GPUaccelerated code for local AbelianHiggs 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 AbelianHiggs 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 bestfit 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.
 Publication:

Physical Review D
 Pub Date:
 August 2020
 DOI:
 10.1103/PhysRevD.102.043503
 arXiv:
 arXiv:2007.12008
 Bibcode:
 2020PhRvD.102d3503C
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Phenomenology;
 Physics  Computational Physics
 EPrint:
 13 pages, 6 figures, 5 tables