Machine Learning the Cosmic Curvature in a Model-independent Way

Abstract

Abstract In this work, we achieve the determination of the cosmic curvature ΩK in a cosmological model-independent way, by using the Hubble parameter measurements H(z) and type Ia supernovae (SNe Ia). In our analysis, two nonlinear interpolating tools are used to reconstruct the Hubble parameter, one is the Artificial Neural Network (ANN) method, and the other is the Gaussian process (GP) method. We find that ΩK based on the GP method can be greatly influenced by the prior of H0, while the ANN method can overcome this. Therefore, the ANN method may have more advantages than GP in the measurement of the cosmic curvature. Based on the ANN method, we find a spatially open universe is preferred by the current H(z) and SNe Ia data, and the difference between our result and the value inferred from Planck CMB is 1.6σ. In order to test the reliability of the ANN method, and the potentiality of the future gravitational waves (GW) standard sirens in the measurement of the cosmic curvature, we constrain ΩK using the simulated Hubble parameter and GW standard sirens in a model-independent way. We find that the ANN method is reliable and unbiased, and the error of ΩK is ∼0.186 when 100 GW events with electromagnetic counterparts are detected, which is $\sim 56\%$ smaller than that constrained from the Pantheon SNe Ia. Therefore, the data-driven method based on ANN has potential in the measurement of the cosmic curvature.