On the Amplitude and Stokes Parameters of a Stochastic Gravitational-Wave Background

TL;DR

This paper compares amplitude-based and Stokes parameter methods for describing stochastic gravitational-wave backgrounds, highlighting the superior ability of Stokes parameters to characterize anisotropic and correlated backgrounds.

Contribution

It introduces and evaluates the use of Stokes parameters for analyzing stochastic gravitational-wave backgrounds, demonstrating their advantages over traditional amplitude power spectra.

Findings

Stokes parameters can describe anisotropic backgrounds.

Stokes spectra are sensitive to spatial distribution of sources.

Amplitude power spectra cannot capture anisotropy.

Abstract

The direct detection of gravitational waves has provided new opportunities for studying the universe, but also new challenges, such as the detection and characterization of stochastic gravitational-wave backgrounds at different gravitational-wave frequencies. In this paper we examine two different methods for their description, one based on the amplitude of a gravitational-wave signal and one on its Stokes parameters. We find that the Stokes parameters are able to describe anisotropic and correlated backgrounds, whereas the usual power spectra of the amplitudes cannot -- i.e. the Stokes spectra are sensitive to properties such as the spatial distribution of the gravitational-wave sources in a realistic backgrounds.