Gravitational wave standard sirens: A brief review of cosmological parameter estimation

TL;DR

Gravitational wave standard sirens offer a promising, independent method for measuring cosmic distances and constraining cosmological parameters, with recent advances and future prospects highlighted.

Contribution

This review summarizes recent progress in GW standard siren cosmology, emphasizing their ability to break parameter degeneracies and discussing systematic uncertainties and future combined probes.

Findings

Recent $H_0$ constraints from GW observations

Potential of GW standard sirens to break cosmological degeneracies

Importance of combining GW with other late-universe probes

Abstract

Gravitational wave (GW) observations are expected to serve as a powerful and independent probe of the expansion history of the universe. By providing direct and calibration-free measurements of luminosity distances through waveform analysis, GWs provide a fundamentally different and potentially more robust approach to measuring cosmic-scale distances compared to traditional electromagnetic (EM) observations, which is known as the standard siren method. In this review, we present an overview of recent developments in GW standard siren cosmology, including up-to-date $H_0$ constraints, and prospects for constraining cosmological parameters using future GW detections. A central focus of this review is the unique ability of GW observations to break cosmological parameter degeneracies inherent in the EM observations. We also briefly highlight the impact of systematic uncertainties, such as detector calibration, weak lensing, peculiar velocities, and host-galaxy catalog completeness, and corresponding potential mitigation strategies, which currently limit the constraint precision of cosmological parameters. Looking forward, we highlight the importance of combining GW standard sirens with other emerging late-universe cosmological probes such as fast radio bursts, 21 cm intensity mapping, and strong gravitational lensing to forge a precise cosmological probe for exploring the late universe.