Cosmic distances probed using the BAO ring

TL;DR

This paper introduces a new method to measure cosmic distances using the BAO peak positions in the 2D correlation function, avoiding systematic uncertainties from RSD modeling, and achieves competitive precision with current data.

Contribution

A novel, model-independent approach to determine radial and transverse cosmic distances from BAO peak positions, bypassing RSD-related systematics.

Findings

Achieved approximately 2% accuracy on transverse distance D_A

Achieved approximately 5% accuracy on radial distance H^{-1}

Results are competitive with existing BAO analyses

Abstract

The cosmic distance can be precisely determined using a `standard ruler' imprinted by primordial baryon acoustic oscillation (hereafter BAO) in the early Universe. The BAO at the targeted epoch is observed by analysing galaxy clustering in redshift space (hereafter RSD) for which a theoretical formulation is not yet fully understood, and thus makes this methodology unsatisfactory. The BAO analysis following a full RSD modelling is contaminated by systematic uncertainties due to a non-linear smearing effects such as non-linear corrections and by random viral velocity of galaxies. However, the BAO can be probed independently of RSD contamination using the BAO peak positions located in the 2D anisotropic correlation function. A new methodology is presented to measure peak positions, to test whether it is also contaminated by the same systematics in RSD, and to provide the radial and transverse cosmic distances determined by the 2D BAO peak positions. We find that in our model independent anisotropic clustering analysis we can obtain about $2\%$ and $5\%$ constraints on $D_A$ and $H^{-1}$ respectively with current BOSS data, which is competitive with other analysis.