We measure the large-scale real-space power spectrum P ( k ) using luminous red galaxies ( LRGs ) in the Sloan Digital Sky Survey ( SDSS ) and use this measurement to sharpen constraints on cosmological parameters from the Wilkinson Microwave Anisotropy Probe ( WMAP ) .
We employ a matrix-based power spectrum estimation method using Pseudo-Karhunen-Loève eigenmodes , producing uncorrelated minimum-variance measurements in 20 k -bands of both the clustering power and its anisotropy due to redshift-space distortions , with narrow and well-behaved window functions in the range 0.01 h / { Mpc } < k < 0.2 h / { Mpc } .
Results from the LRG and main galaxy samples are consistent , with the former providing higher signal-to-noise .
Our results are robust to omitting angular and radial density fluctuations and are consistent between different parts of the sky .
They provide a striking confirmation of the predicted large-scale \Lambda CDM power spectrum .
Combining only SDSS LRG and WMAP data places robust constraints on many cosmological parameters that complement prior analyses of multiple data sets .
The LRGs provide independent cross-checks on \Omega _ { m } and the baryon fraction in good agreement with WMAP .
Within the context of flat \Lambda CDM models , our LRG measurements complement WMAP by sharpening the constraints on the matter density , the neutrino density and the tensor amplitude by about a factor of two , giving \Omega _ { m } = 0.24 \pm 0.02 ( 1 \sigma ) , \sum m _ { \nu } \mathrel { \hbox to 0.0 pt { \lower 3.0 pt \hbox { $ \mathchar 536 $ } \hss } % \raise 2.0 pt \hbox { $ \mathchar 316 $ } } 0.9 eV ( 95 % ) and r < 0.3 ( 95 % ) .
Baryon oscillations are clearly detected and provide a robust measurement of the comoving distance to the median survey redshift z = 0.35 independent of curvature and dark energy properties .
Within the \Lambda CDM framework , our power spectrum measurement improves the evidence for spatial flatness , sharpening the curvature constraint \Omega _ { tot } = 1.05 \pm 0.05 from WMAP alone to \Omega _ { tot } = 1.003 \pm 0.010 .
Assuming \Omega _ { tot } = 1 , the equation of state parameter is constrained to w = -0.94 \pm 0.09 , indicating the potential for more ambitious future LRG measurements to provide precision tests of the nature of dark energy .
All these constraints are essentially independent of scales k > 0.1 h /Mpc and associated nonlinear complications , yet agree well with more aggressive published analyses where nonlinear modeling is crucial .