Nanohertz gravitational waves from cosmic strings and dark photon dark matter

TL;DR

This paper explores how cosmic strings and dark photon dark matter could explain recent nano-Hz gravitational wave signals observed by pulsar timing arrays, linking new physics to dark matter and gravitational wave detection.

Contribution

It investigates the combined implications of cosmic strings and dark photon dark matter for PTA signals and dark matter abundance, proposing a unified explanation.

Findings

Cosmic strings can produce gravitational waves consistent with PTA observations.

Dark photon dark matter with mass 10^{-6}--10^{-4} eV can be generated from cosmic string decay.

The model predicts detectable signals across multiple gravitational wave frequency bands.

Abstract

The recent observations by pulsar timing array (PTA) experiments suggest the existence of stochastic gravitational wave background in the nano-Hz range. It can be a hint for the new physics and cosmic string is one of the promising candidate. In this paper, we study the implication of the PTA result for cosmic strings and dark photon dark matter produced by the decay of cosmic string loops. It can simultaneously explain the PTA result and present dark matter abundance for the dark photon mass m~10^{-6}--10^{-4}eV. Implications for the gravitational wave detection with multi-frequency bands are also discussed.