## Abstract

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 k_{max} = 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: χ^{2} = 39.6 for 40 degrees of freedom for the best-fitting Δ cold dark matter (ΔCDM) model. We find Ω_{m}h^{2}(n_{s}/0.96)^{1.2} = 0.141^{+0.010}_{-0.012} for a power-law primordial power spectrum with spectral index n_{s} and Ω_{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}/D_{V}(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 Ω_{m} = 0.289 ± 0.019 and H_{0} = 69.4 ± 1.6 km s^{-1} Mpc^{-1}. Allowing ∑ for massive neutrinos in ΔCDM, we find σm_{ν} < 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^{+1.8}_{-1.7}. Combining also with the Kowalski et al. supernova sample, we find Ω_{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/.

Original language | English (US) |
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Pages (from-to) | 60-85 |

Number of pages | 26 |

Journal | Monthly Notices of the Royal Astronomical Society |

Volume | 404 |

Issue number | 1 |

DOIs | |

State | Published - May 2010 |

## All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science

## Keywords

- Cosmology: observations
- Galaxies: haloes
- Galaxies: statistics
- Large-scale structure of Universe