Cosmological constraints from the clustering of the Sloan Digital Sky Survey DR7 luminous red galaxies

We present the power spectrum of the reconstructed halo density field derived from a sample of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS) Seventh Data Release (DR7). The halo power spectrum has a direct connection to the underlying dark matter power for k <= 0.2 h Mpc(-1), well into the quasi-linear regime. This enables us to use a factor of similar to 8 more modes in the cosmological analysis than an analysis with k(max) = 0.1 h Mpc(-1), as was adopted in the SDSS team analysis of the DR4 LRG sample. The observed halo power spectrum for 0.02< k < 0.2 h Mpc(-1) is well fitted by our model: chi(2) = 39.6 for 40 degrees of freedom for the best-fitting Lambda cold dark matter (Lambda CDM) model. We find Omega(m)h(2)(n(s)/0.96)(1.2) = 0.141(-0.012+)(0.010) for a power-law primordial power spectrum with spectral index ns and Omega(b)h(2) = 0.022 65 fixed, consistent with cosmic microwave background measurements. The halo power spectrum also constrains the ratio of the comoving sound horizon at the baryon-drag epoch to an effective distance to z = 0.35: r(s)/DV(0.35) = 0.1097(-0.0042)(+0.0039). Combining the halo power spectrum measurement with the Wilkinson Microwave Anisotropy Probe (WMAP) 5 year results, for the flat Lambda CDM model we find Omega(m) = 0.289 +/- 0.019 and H-0 = 69.4 +/- 1.6 kms(-1) Mpc(-1). Allowing for massive neutrinos in Lambda CDM, we find Sigma m(nu) < 0.62 eV at the 95 per cent confidence level. If we instead consider the effective number of relativistic species N-eff as a free parameter, we find N-eff = 4.8(-1.7)(+1.8). Combining also with the Kowalski et al. supernova sample, we find Omega(tot) = 1.011 +/- 0.009 and w = -0.99 +/- 0.11 for an open cosmology with constant dark energy equation of state w. The power spectrum and a module to calculate the likelihoods are publicly available at http://lambda.gsfc.nasa.gov/toolbox/lrgdr/.