A New Gravitational Wave Probe to the Nature of Dark Energy from the Aging of the Universe

TL;DR

This paper proposes a novel method to probe dark energy by monitoring the aging of the universe through gravitational wave signals from binary mergers, enabling direct measurement of dark energy properties over time.

Contribution

It introduces a new approach to infer dark energy's equation of state using gravitational wave observations of binary mergers over several years, without external calibration.

Findings

Potential to detect dark energy EoS parameter with 5σ significance

Method can distinguish dark energy evolution over cosmic time

Requires next-generation gravitational wave detectors

Abstract

One of the most dominant energy budgets in the Universe is Dark Energy, which remains enigmatic since its existence was first claimed based on observations of late-time cosmic acceleration. We propose a new way of inferring the dark energy equation of state (EoS) by measuring the aging of the Universe using only gravitational wave (GW) signals from coalescing binary compact objects of any masses. We show that the behavior of dark energy as the Universe ages will lead to a change in the observed chirp mass of GW sources inferred from observations of different stages of their coalescence. This change can be studied by monitoring a coherent source over a few years, with two well-separated GW frequencies. With a coordinated network of GW detectors that can reach a sensitivity of Big Bang Observer, we can reach a $5\sigma$ detection of the dark energy EoS parameter $w_0=-1$ and its variation with cosmic time by using stellar origin binary black holes and binary neutron stars up to high redshift over 10 years of observation time without using any external calibrator. If the next generation of GW detectors can achieve this precision, then it can open a new window to discover the fundamental nature of dark energy.