Prospects for cosmological constraints using gravitational wave memory

TL;DR

This paper explores how gravitational wave memory effects, accumulated over cosmological distances, can serve as a new probe of dark energy and the universe's expansion, especially with next-generation detectors.

Contribution

It introduces a novel method to use integrated gravitational wave memory as a sensitive, non-linear cosmological probe, enhancing the potential to study dark energy and address cosmological tensions.

Findings

Integrated GW memory is amplified by a factor of 100 at high redshift.

Cumulative GW memory can reveal non-linear dependencies on cosmological parameters.

Potential sensitivity of GW memory to different dark energy models.

Abstract

The {\Lambda}CDM model has long served as a robust and predictive framework for cosmology, successfully explaining a wide range of observations, including the accelerated expansion of the Universe. However, discrepancies in cosmological parameter estimates and recent findings, such as those from DESI, hint at potential deviations from {\Lambda}CDM. Gravitational wave (GW) observations offer an independent method to probe the nature of dark energy, leveraging GWs from compact binary mergers as standard candles. In this study, we demonstrate that the integrated GW memory over cosmological distances encodes a unique imprint of the background spacetime. Unlike previous analyses, our approach captures non-linear dependencies on cosmological quantities, resulting in an enhancement of the integrated GW memory by a factor of 100 for high-redshift sources well within the sensitivity range of next-generation detectors like Cosmic Explorer and the Einstein Telescope. We find that despite the diminishing strength of individual GWs at high redshifts, their cumulative effect leads to a significant amplification, akin to the integrated Sachs-Wolfe effect, offering a potential new avenue for cosmological studies. By examining a range of dark energy models, we reveal that GW memory is potentially highly sensitive to the underlying cosmological framework, making it a promising probe of dark energy. This novel approach presents the possibility of a fresh perspective to address persistent cosmological tensions, and the nature of dark energy.