Date Published:

August 1, 2013

Abstract:

We explore the cosmological implications of the clustering wedges,ξ_⊥(s) and ξ_∥(s), of the CMASS DataRelease 9 sample of the Sloan Digital Sky Survey III (SDSS-III) BaryonOscillation Spectroscopic Survey. These clustering wedges are defined byaveraging the full two-dimensional correlation function, ξ(μ, s),over the ranges 0 < μ < 0.5 and 0.5 < μ < 1,respectively. These measurements allow us to constrain the parametercombinations D_A(z)/r_s(z_d) = 9.03± 0.21 and cz/(r_s(z_d)H(z)) = 12.14 ±0.43 at the mean redshift of the sample, z = 0.57. We combine theinformation from the clustering wedges with recent measurements ofcosmic microwave background (CMB), baryon acoustic oscillations and TypeIa supernovae to obtain constraints on the cosmological parameters ofthe standard Λ cold dark matter (ΛCDM) model and a numberof potential extensions. The information encoded in the clusteringwedges is most useful when the dark energy equation of state is allowedto deviate from its standard ΛCDM value. The combination of alldata sets shows no evidence of a deviation from a constant dark energyequation of state, in which case we find w_DE = -1.013± 0.064, in complete agreement with a cosmological constant. Weexplore potential deviations from general relativity (GR) byconstraining the growth rate f(z) = d ln D(a)/d ln a, in which case thecombination of the CMASS clustering wedges with CMB data implies f(z =0.57) = 0.719_-0.096^+0.092, in accordance with thepredictions of GR. Our results clearly illustrate the additionalconstraining power of anisotropic clustering measurements with respectto that of angle-averaged quantities.

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