Comment on the claimed radial BAO detection by Gaztanaga et al
  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.
