Isotropic vs. anisotropic components of BAO data: a tool for model selection

Abstract

We conduct a selective analysis of the isotropic (DV) and anisotropic (AP) components of the most recent Baryon Acoustic Oscillations (BAO) data. We find that these components provide significantly different constraints and could provide strong diagnostics for model selection, also in view of more precise data to arrive. For instance, in the ΛCDM model we find a mild tension of ∼ 2 σ for the Ωm estimates obtained using DV and AP separately. Considering both Ωk and w as free parameters, we find that the concordance model is in tension with the best-fit values provided by the BAO data alone at 2.2σ. We complemented the BAO data with the Supernovae Ia (SNIa) and Observational Hubble datasets to perform a joint analysis on the ΛCDM model and its standard extensions. By assuming ΛCDM scenario, we find that these data provide H0 = 69.4 ± 1.7 km/s Mpc−1 as the best-fit value for the present expansion rate. In the kΛCDM scenario we find that the evidence for acceleration using the BAO data alone is more than ∼ 5.8σ, which increases to 8.4 σ in our joint analysis.