Baryon acoustic oscillations in the Sloan Digital Sky Survey Data Release 7 galaxy sample
Abstract
The spectroscopic Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) galaxy sample represents the final set of galaxies observed using the original SDSS target selection criteria. We analyse the clustering of galaxies within this sample, including both the luminous red galaxy and main samples, and also include the 2degree Field Galaxy Redshift Survey data. In total, this sample comprises 893319 galaxies over 9100deg^{2}. Baryon acoustic oscillations (BAO) are observed in power spectra measured for different slices in redshift; this allows us to constrain the distanceredshift relation at multiple epochs. We achieve a distance measure at redshift z = 0.275, of r_{s}(z_{d})/D_{V}(0.275) = 0.1390 +/ 0.0037 (2.7 per cent accuracy), where r_{s}(z_{d}) is the comoving sound horizon at the baryondrag epoch, D_{V}(z) ≡ [(1 + z)^{2}D^{2}_{A}cz/H(z)]^{1/3}, D_{A}(z) is the angular diameter distance and H(z) is the Hubble parameter. We find an almost independent constraint on the ratio of distances D_{V}(0.35)/D_{V}(0.2) = 1.736 +/ 0.065, which is consistent at the 1.1σ level with the bestfitting Λ cold dark matter model obtained when combining our z = 0.275 distance constraint with the Wilkinson Microwave Anisotropy Probe 5year (WMAP5) data. The offset is similar to that found in previous analyses of the SDSS DR5 sample, but the discrepancy is now of lower significance, a change caused by a revised error analysis and a change in the methodology adopted, as well as the addition of more data. Using WMAP5 constraints on Ω_{b}h^{2} and Ω_{c}h^{2}, and combining our BAO distance measurements with those from the Union supernova sample, places a tight constraint on Ω_{m} = 0.286 +/ 0.018 and H_{0} = 68.2 +/ 2.2kms^{1}Mpc^{1} that is robust to allowing Ω_{k} ≠ 0 and w ≠ 1. This result is independent of the behaviour of dark energy at redshifts greater than those probed by the BAO and supernova measurements. Combining these data sets with the full WMAP5 likelihood constraints provides tight constraints on both Ω_{k} = 0.006 +/ 0.008 and w = 0.97 +/ 0.10 for a constant dark energy equation of state.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 February 2010
 DOI:
 10.1111/j.13652966.2009.15812.x
 arXiv:
 arXiv:0907.1660
 Bibcode:
 2010MNRAS.401.2148P
 Keywords:

 cosmology: observations;
 distance scale;
 largescale structure of Universe;
 Astrophysics  Cosmology and Extragalactic Astrophysics
 EPrint:
 22 pages, 16 figures, minor changes to match version published in MNRAS