Comment on the claimed radial BAO detection by Gaztanaga et al

TL;DR

This paper critiques a recent claim of radial BAO detection, clarifying that gravitational lensing effects are negligible and the observed feature is likely noise, not a physical BAO signal.

Contribution

It provides a critical analysis showing that the claimed BAO detection by Gaztanaga et al. is not supported by physical effects and is consistent with noise.

Findings

Lensing has negligible impact on BAO peak measurement.

The identified feature is consistent with noise, not a physical BAO signal.

The interpretation by Gaztanaga et al. is incorrect.

Abstract

Gaztanaga et al. have recently claimed to measure the Baryon Acoustic Oscillation (BAO) scale in the radial direction from the publicly available SDSS DR6 data. They focus on the correlation function of Luminous Red Galaxies (LRG) close to the line-of-sight direction to find a feature that they identify as the BAO peak, arguing that a magnification bias effect from gravitational lensing increases the amplitude of the BAO peak, facilitating its detection. In this Comment, we clarify that lensing has a negligible impact on the measurement of the BAO peak, and that the interpretation by Gaztanaga et al. is incorrect. The feature they identify in the LRG correlation function near the line-of-sight cannot be explained by any known physical effect and is in fact consistent with noise.