A null test of the Cosmological Principle with BAO measurements

The assumption of a Friedmann-LemaItre-Roberton-Walker (FLRW) Universe is one of the fundamental pillars of modern Cosmology. It is crucial to confront it against cosmological observations in order to confirm (or rule out) the validity of the ACDM paradigm. We perform a consistency test of the FLRW metric using measurements of both radial and transversal modes of Baryonic Acoustic Oscillations in a model-independent fashion using Gaussian Processes. The impact of different prior assumptions for the sound horizon scale and the Hubble Constant is also explored. We find a mild deviation of the FLRW hypothesis (greater than or similar to 3 sigma - confidence level) at lower redshift ranges (0.1 < z < 0.3) under the assumption the SHOES H-0 prior, which does not occur for the H-0 prior by Planck. We also find that different reconstruction kernels reduce the statistical significance of such a deviation. At higher redshift ranges, the null test are able to confirm the FLRW assumption within 3 sigma - confidence level regardless of the priors. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study conducted a consistency test of the FLRW metric using Gaussian Processes, finding a mild deviation at lower redshift ranges and confirming the FLRW assumption at higher redshift ranges regardless of the priors.