Gravitational waves from cosmic strings associated with pseudo-Nambu-Goldstone dark matter

TL;DR

This paper explores how cosmic strings from a specific dark matter model can produce detectable gravitational waves, with current and future experiments potentially observing these signals.

Contribution

It introduces a UV-complete pseudo-Nambu-Goldstone dark matter model with high-scale U(1) symmetry breaking, linking it to gravitational wave signatures from cosmic strings.

Findings

High-tension cosmic strings generate a detectable gravitational wave background.

Most viable model parameters can be probed by future gravitational wave experiments.

The model naturally evades direct detection constraints while satisfying phenomenological bounds.

Abstract

We study stochastic gravitational waves from cosmic strings generated in an ultraviolet-complete model for pseudo-Nambu-Goldstone dark matter with a hidden $\mathrm{U(1)}$ gauge symmetry. The dark matter candidate in this model can naturally evade direct detection bounds and easily satisfy other phenomenological constraints. The bound on the dark matter lifetime implies an ultraviolet scale higher than $10^9~\mathrm{GeV}$. The spontaneous $\mathrm{U(1)}$ symmetry breaking at such a high scale would induce cosmic strings with high tension, resulting in a stochastic gravitational wave background with a high energy density. We investigate the constraints from current gravitational wave experiments as well as the future sensitivity. We find that most viable parameter points can be well studied in future gravitational wave experiments.