High precision measurement of cosmic curvature: from gravitational waves and cosmic chronometer

TL;DR

This paper proposes an improved method using gravitational wave data from DECIGO and cosmic chronometers to measure cosmic curvature with high precision, addressing existing tensions and providing constraints comparable to Planck 2018 results.

Contribution

The study introduces a novel approach combining gravitational wave standard sirens and cosmic chronometers to accurately determine cosmic curvature without relying heavily on specific cosmological models.

Findings

DECIGO can constrain cosmic curvature to $oxed{-0.007 ext{±}0.016}$

Zero curvature can be established at $oxed{0.12}$ precision in model-dependent analysis

Constraints are comparable to Planck 2018 CMB results

Abstract

Although the spatial curvature has been measured with very high precision, it still suffers from the well known cosmic curvature tension. In this paper, we propose an improved method to determine the cosmic curvature, by using the simulated data of binary neutron star mergers observed by the second generation space-based DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO). By applying the Hubble parameter observations of cosmic chronometers to the DECIGO standard sirens, we explore different possibilities of making measurements of the cosmic curvature referring to a distant past: one is to reconstruct the Hubble parameters through the Gaussian process without the influence of hypothetical models, and the other is deriving constraints on $\Omega_K$ in the framework of non-flat $\Lambda$ cold dark matter model. It is shown that in the improved method DECIGO could provide a reliable and stringent constraint on the cosmic curvature ($\Omega_{K} = -0.007\pm0.016$), while we could only expect the zero cosmic curvature to be established at the precision of $\Delta \Omega_K=0.12$ in the second model-dependent method. Therefore, our results indicate that in the framework of methodology proposed in this paper, the increasing number of well-measured standard sirens in DECIGO could significantly reduce the bias of estimations for cosmic curvature. Such constraint is also comparable to the precision of Planck 2018 results with the newest cosmic microwave background (CMB) observations ($\Delta \Omega_{K} \approx 0.018$), based on the concordance $\Lambda$CDM model.