Measurement on the cosmic curvature using the Gaussian process method

Abstract

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 $\Omega _{k0}h^2=0.117^{+0.058}_{-0.045}$ and no deviation from Λ cold dark matter (ΛCDM) model is found.