Measuring the Baryon Acoustic Oscillation scale using the SDSS and 2dFGRS

We introduce a method to constrain general cosmological models using Baryon Acoustic Oscillation (BAO) distance measurements from galaxy samples covering different redshift ranges, and apply this method to analyse samples drawn from the SDSS and 2dFGRS. BAO are detected in the clustering of the combined 2dFGRS and SDSS main galaxy samples, and measure the distance‐redshift relation at z = 0.2. BAO in the clustering of the SDSS luminous red galaxies measure the distance‐redshift relation at z = 0.35. The observed scale of the BAO calculated from these samples and from the combined sample are jointly analysed using estimates of the correlated errors, to constrain the form of the distance measure DV (z) � [(1+ z) 2 D 2 cz/H(z)] 1/3 . Here DA is the angular diameter distance, and H(z) is the Hubble parameter. This gives rs/DV (0.2) = 0.1980±0.0058 and rs/DV (0.35) = 0.1094±0.0033 (1σ errors), with correlation coefficient of 0.39, where rs is the comoving sound horizon scale at recombination. Matching the BAO to have the same measured scale at all redshifts then gives DV (0.35)/DV (0.2) = 1.812 ± 0.060. The recovered ratio is roughly consistent