Measurement on the cosmic curvature using the Gaussian process method. Issue 2 (19th May 2021) - Yang, Yingjie
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 Ω k 0 h 2 = 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.