Breaking the Strings: the signatures of Cosmic String Loop Fragmentation

TL;DR

This paper investigates how fragmentation affects the distribution and evolution of cosmic string loops, introducing new numerical methods to model these effects and highlighting their significance for accurate cosmic string loop predictions.

Contribution

The authors develop a novel formulation and numerical approaches to incorporate fragmentation and gravitational radiation into cosmic string loop distribution models.

Findings

Fragmentation causes decay in large-scale loop number density.

Loop distribution deviates from a pure power-law due to fragmentation.

Fragmentation is essential for accurate cosmic string loop modeling.

Abstract

We study the impact of fragmentation on the cosmic string loop number density, using an approach inspired by the three-scale model and a Boltzmann equation. We build a new formulation designed to be more amenable to numerical resolution and present two complementary numerical methods to obtain the full loop distribution including the effect of fragmentation and gravitational radiation. We show that fragmentation generically predicts a decay of the loop number density on large scales and a deviation from a pure power-law. We expect fragmentation to be crucial for the calibration of loop distribution models.