Evolution of local and global monopole networks

TL;DR

This paper extends a model to describe the evolution of local and global monopole networks, highlighting differences in their dynamics, energy loss mechanisms, and scaling behaviors, with implications for understanding cosmic topological defects.

Contribution

It introduces an extended velocity-dependent one-scale model tailored for monopoles, incorporating monopole-specific forces and energy loss processes, and compares results with previous simulations.

Findings

Local monopoles' correlation length is highly sensitive to annihilation rates.

Global monopoles tend to exhibit linear scaling due to long-range forces.

Qualitative agreement with previous numerical simulations was achieved.

Abstract

We present an extension of the velocity-dependent one-scale model for cosmic string evolution, which is suitable for describing the evolution of local and global monopole networks. We discuss the key dynamical features that need to be accounted for, in particular the fact that the driving force is due to the other monopoles (rather than being due to local curvature as in the case of extended objects) and new forms of energy loss terms due to monopole-antimonopole capture and annihilation. For the case of local monopoles we recover and generalize the results of Preskill, suggesting that the scaling law for the monopole correlation length is very sensitive to the annihilation rate. On the other hand, for global monopoles the long-range forces generically lead to linear scaling (just like in the case of local cosmic strings). In this case we also find good qualitative agreement between our results and the numerical simulations of Bennett & Rhie and Yamaguchi, although future high-resolution simulations will be needed for quantitative comparisons.