Measurement on the cosmic curvature using the Gaussian process method

ABSTRACT Inflation predicts that the Universe is spatially flat. The Planck 2018 measurements of the cosmic microwave background anisotropy favour a spatially closed universe at more than 2σ confidence level. We use model-independent methods to study the issue of cosmic curvature. The method reconstructs the Hubble parameter H (z) from cosmic chronometers data with the Gaussian process method. The distance modulus is then calculated with the reconstructed function H (z) and fitted by Type Ia supernovae data. Combining the cosmic chronometers and Type Ia supernovae data, we obtain Ωk0h2 = 0. 102 ± 0. 066 that is consistent with a spatially flat universe at the 2σ confidence level. By adding the redshift-space distortions data to the Type Ia supernovae data with a proposed novel model-independent method, we obtain ₊₀h²=0. 117^+0. 058-₀. ₀₄₅ and no deviation from Λ cold dark matter (ΛCDM) model is found.