Cosmic String Loops and Gravitational Radiation

TL;DR

This paper reviews cosmic string network evolution and gravitational signatures, emphasizing the uncertainty in loop sizes, and presents a model suggesting most loops are very small, impacting observational signatures.

Contribution

It introduces an analytic model combined with simulations indicating most cosmic string loops are very small, refining predictions of their gravitational signatures.

Findings

90% of string energy in small loops at gravitational radiation scale

10% of string energy in loops near the Hubble scale

Implications for cosmic string observational signatures

Abstract

Understanding of the signatures of cosmic string networks is limited by a large uncertainty in the sizes at which cosmic string loops form. We review cosmic string network evolution, and the gravitational signatures, with emphasis on this uncertainty. We then review a recent analytic model of cosmic string networks. In combination with recent simulations, this suggests that 90% of the string goes into very small loops, at the gravitational radiation scale, and 10% into loops near the Hubble scale. We discuss cosmic string signatures in such a scenario, and the `inverse problem' of determining the microscopic cosmic string properties from observations.