The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological constraints from the full shape of the clustering wedges

TL;DR

This paper uses clustering wedges from SDSS-III BOSS to constrain cosmological parameters, confirming the standard model and testing extensions, with results consistent with a cosmological constant and general relativity.

Contribution

It introduces the use of clustering wedges from BOSS DR9 to improve cosmological constraints and demonstrates their effectiveness compared to angle-averaged measurements.

Findings

Constraints on D_A(z)/r_s(z_d) and cz/(r_s(z_d)H(z)) with high precision.

No evidence for deviation from a cosmological constant (w_DE ≈ -1).

Growth rate measurements consistent with general relativity.

Abstract

We explore the cosmological implications of the clustering wedges, xi_perp(s) and xi_para(s), of the CMASS Data Release 9 (DR9) sample of the Baryon Oscillation Spectroscopic Survey (BOSS). These clustering wedges are defined by averaging the full two-dimensional correlation function, xi(mu,s), over the ranges 0<mu<0.5 and 0.5<mu<1, respectively. These measurements allow us to constrain the parameter combinations 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 redsfhit of the sample, z=0.57. We combine the information from the clustering wedges with recent measurements of CMB, BAO and type Ia supernovae to obtain constraints on the cosmological parameters of the standard LCDM model and a number of potential extensions. The information encoded in the clustering wedges is most useful when the dark energy equation of state is allowed to deviate from its standard LCDM value. The combination of all datasets shows no evidence of a deviation from a constant dark energy equation of state, in which case we find w_DE = -1.013 +- 0.064, in complete agreement with a cosmological constant. We explore potential deviations from general relativity by constraining the growth rate f(z)=d ln D(a)/ d ln a, in which case the combination of the CMASS clustering wedges with CMB data implies f(z=0.57)=0.719 +- 0.094, in accordance with the predictions of GR. Our results clearly illustrate the additional constraining power of anisotropic clustering measurements with respect to that of angle-averaged quantities.