Quantification of 2D vs 3D BAO tension using SNIa as a redshift interpolator and test of the Etherington relation

TL;DR

This study compares 2D and 3D BAO measurements using SNIa as a redshift interpolator, finding a tension of up to 4.6 sigma, while testing the Etherington relation and avoiding cosmological model dependence.

Contribution

It introduces a calibration-independent analysis of BAO data and tests the cosmic distance duality relation without assuming specific cosmological models.

Findings

Tension between 2D and 3D BAO data at up to 4.6 sigma.

No evidence found for violation of the distance duality relation.

Results are robust across different BAO datasets and SNIa compilations.

Abstract

Several studies in the literature have found a disagreement between data on Baryon Acoustic Oscillations (BAO) derived using two distinct methodologies: the two-dimensional (2D or angular) BAO, which extracts the BAO signal from the angular two-point correlation function; and the three-dimensional (3D) BAO, which also exploits the radial signal imprinted on the large-scale structure of the universe. This discrepancy is worrisome, since many of the points contained in these data sets are obtained from the same catalogs of tracers, so we would expect them to be consistent. Since BAO measurements play a pivotal role in the building of the inverse distance ladder, this mismatch impacts the discourse on the Hubble tension and the theoretical solutions to the latter. So far, the discrepancy between 2D and 3D BAO has been only pointed out in the context of fitting analyses of cosmological models or parametrizations that involve a concrete calibration of the comoving sound horizon at the baryon-drag epoch. In this Letter, we avoid the use of any calibration and cosmological model, assuming that the Etherington (a.k.a distance duality) relation holds. We use state-of-the-art measurements in our analysis, and study how the results change when the angular components of the 3D BAO data from BOSS/eBOSS are substituted by the recent data from DESI Y1. We find the tension to exist at the level of $\sim 2\sigma$ and $\sim 2.5\sigma$, respectively, when the SNIa of Pantheon+ are used, and at $\sim 4.6\sigma$ when they are replaced with those of DES Y5. We then apply a calibrator-independent method to investigate the robustness of the distance duality relation when analyzed not only with 3D BAO measurements, but also with 2D BAO. We do not find any hint for a violation of the cosmic distance duality relation in any of the considered data sets. [abridged]