Projected constraints on the cosmic (super)string tension with future gravitational wave detection experiments

TL;DR

This paper forecasts how future gravitational wave experiments can constrain cosmic string tensions by analyzing their spectra across different frequency bands and model parameters, providing semi-analytic relations for tension limits.

Contribution

It introduces semi-analytic formulas linking gravitational wave background measurements to cosmic string tension constraints, considering various experimental setups and cosmic string models.

Findings

Future experiments can significantly improve tension constraints.

Different frequency bands probe distinct parts of the cosmic string spectrum.

Constraints depend on the cosmic string loop formation scale.

Abstract

We present projected constraints on the cosmic string tension, $G\mu/c^2$, that could be achieved by future gravitational wave detection experiments and express our results as semi-analytic relations of the form $G\mu(\Omega_{\rm gw}h^2)/c^2$, to allow for direct computation of the tension constraints for future experiments. These results can be applied to new constraints on $\ogwh$ as they are imposed. Experiments operating in different frequency bands probe different parts of the gravitational wave spectrum of a cosmic string network and are sensitive to different uncertainties in the underlying cosmic string model parameters. We compute the gravitational wave spectra of cosmic string networks based on the one-scale model, covering all the parameter space accessed by each experiment which is strongly dependent on the birth scale of loops relative to the horizon, $\alpha$. The upper limits on the string tension avoid any assumptions on the model parameters. We perform this investigation for Pulsar Timing Array experiments of different durations as well as ground-based and space-borne interferometric detectors.