Abstract

Cosmic strings are topological defects that arise in particle physics models with a spontaneously broken U(1) symmetry, motivated, for example, by the Peccei-Quinn mechanism. They are predicted to radiate massive particles, gravitational waves and, in the case of a global U(1) symmetry breaking, massless dark matter axions. In order to detect cosmic strings via gravitational waves or to understand their axion emission spectra, we need to model the radiation dependence on certain string parameters. In this talk, I will detail my work modelling the dependence of axion string scalar radiation on the curvature of the string relative to the string width. I will focus on my most recent paper, arXiv:2312.07701 (to appear in PRD ), which uses adaptive mesh refinement simulations of colliding travelling waves along the string to measure the dependence of massive and massless modes on the string curvature. I will comment on the potential implications of this work for gravitational wave predictions from cosmic strings. If time allows, I will also outline some work in progress on modelling the massive radiation from Nambu-Goto-like cusps using simulations of Abelian-Higgs strings, and how this will be extended using full numerical relativity.