Measuring the Baryon Acoustic Oscillation scale using the Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey
Abstract
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 Sloan Digital Sky Survey (SDSS) and 2dF Galaxy Redshift Survey (2dFGRS). BAOs are detected in the clustering of the combined 2dFGRS and SDSS main galaxy samples, and measure the distanceredshift relation at z = 0.2. BAOs in the clustering of the SDSS luminous red galaxies measure the distanceredshift relation at z = 0.35. The observed scales of the BAOs 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 D_{V}(z) ≡ [(1 + z)^{2}D^{2}_{A}cz/H(z)]^{1/3}. Here D_{A} is the angular diameter distance, and H(z) is the Hubble parameter. This gives r_{s}/D_{V}(0.2) = 0.1980 +/ 0.0058 and r_{s}/D_{V}(0.35) = 0.1094 +/ 0.0033 (1σ errors), with a correlation coefficient of 0.39, where r_{s} is the comoving sound horizon scale at recombination. Matching the BAOs to have the same measured scale at all redshifts then gives D_{V}(0.35)/D_{V}(0.2) = 1.812 +/ 0.060. The recovered ratio is roughly consistent with that predicted by the higher redshift Supernova Legacy Survey (SNLS) supernova data for Λ cold dark matter cosmologies, but does require slightly stronger cosmological acceleration at a low redshift. If we force the cosmological model to be flat with constant w, then we find Ω_{m} = 0.249 +/ 0.018 and w = 1.004 +/ 0.089 after combining with the SNLS data, and including the WMAP measurement of the apparent acoustic horizon angle in the cosmic microwave background.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 November 2007
 DOI:
 10.1111/j.13652966.2007.12268.x
 arXiv:
 arXiv:0705.3323
 Bibcode:
 2007MNRAS.381.1053P
 Keywords:

 cosmology: observations;
 distance scale;
 largescale structure of Universe;
 Astrophysics
 EPrint:
 14 pages, 13 figures, MNRAS accepted