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 ~8 more modes in the cosmological analysis than an analysis with kmax = 0.1 h Mpc-1,aswas 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: χ2 = 39.6 for 40 degrees of freedom for the best-fitting Δ cold dark matter (ΔCDM) model. We find Ωmh2(ns/0.96)1.2 = 0.141+0.010-0.012 for a power-law primordial power spectrum with spectral index ns and Ωbh2 = 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: rs/DV(0.35) = 0.1097+0.0039-0.0042. Combining the halo power spectrum measurement with the Wilkinson Microwave Anisotropy Probe (WMAP) 5 year results, for the flat ΔCDM model we find Ωm = 0.289 ± 0.019 and H0 = 69.4 ± 1.6 km s-1 Mpc-1. Allowing ∑ for massive neutrinos in ΔCDM, we find σmν < 0.62 eV at the 95 per cent confidence level. If we instead consider the effective number of relativistic species Neff as a free parameter, we find Neff = 4.8+1.8-1.7. Combining also with the Kowalski et al. supernova sample, we find Ωtot = 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/.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science