Date Published:

August 1, 2013

Abstract:

We present measurements of the anisotropic galaxy clustering from theData Release 9 (DR9) CMASS sample of the Sloan Digital Sky Survey(SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS). We analysethe broad-range shape of the monopole and quadrupole correlationfunctions to obtain constraints, at the effective redshift z = 0.57 ofthe sample, on the Hubble expansion rate H(z), the angular-diameterdistance D_A(z), the normalized growth rate f(z)σ₈(z), the physical matter densityΩ_mh², and the biased amplitude of matterfluctuation bσ₈(z). We obtain {H(0.57),D_A(0.57), f (0.57)σ₈(0.57),Ω_mh², bσ₈(0.57)} =[87.6_{-6.8}^{+6.7} kms^-1 Mpc^-1, 1396 ± 73Mpc, 0.428 ± 0.066, 0.126_{-0.010}^{+0.008}, 1.19 ± 0.14}and their covariance matrix as well. The parameters which are not wellconstrained by our galaxy clustering analysis are marginalized over withwide flat priors. Since no priors from other data sets [i.e. cosmicmicrowave background (CMB)] are adopted and no dark energy models areassumed, our results from BOSS CMASS galaxy clustering alone may becombined with other data sets, i.e. CMB, SNe, lensing or other galaxyclustering data to constrain the parameters of a given cosmologicalmodel. We show that the major power on constraining dark energy from theanisotropic galaxy clustering signal, as compared to theangular-averaged one (monopole), arises from including the normalizedgrowth rate f (z)σ₈(z). In the case of the cosmologicalmodel assuming a constant dark energy equation of state and a flatuniverse (wCDM), our single-probe CMASS constraints, combined with CMB(WMAP9+SPT), yield a value for the dark energy equation-of-stateparameter of w = -0.90 ± 0.11. Therefore, it is important toinclude f (z)σ₈(z) while investigating the nature ofdark energy with current and upcoming large-scale galaxy surveys.

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