The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples

TL;DR

This paper analyzes the full shape of the two-point clustering statistics $\xi(s)$ and clustering wedges $\xi_{\perp}(s)$, $\xi_{\parallel}(s)$ from SDSS-III BOSS DR10/DR11 LOWZ and CMASS to extract cosmological information. The authors develop a perturbation-theory-based model for the anisotropic clustering and map theoretical predictions to the fiducial cosmology used in the data, then perform MCMC analyses across multiple cosmological parameter spaces, combining with Planck/ePlanck, BAO, and SN data. They find no significant departure from LCDM, obtaining tight constraints such as $\Omega_k = 0.0010 \pm 0.0029$, $\sum m_\nu < 0.24$ eV (95% CL), $N_{\rm eff} = 3.31 \pm 0.27$, and $w_{\rm DE} = -1.051 \pm 0.076$, with $f\sigma_8(z)$ measurements in agreement with GR predictions. The full clustering information significantly improves dark energy and growth constraints, showing the robustness of LCDM and the potential of full-shape analyses for precision cosmology.

Abstract

We explore the cosmological implications of the angle-averaged correlation function, xi(s), and the clustering wedges, xi_perp(s) and xi_para(s), of the LOWZ and CMASS galaxy samples from Data Release 10 and 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation from the standard LCDM model. The combination of the information from our clustering measurements with recent data from the cosmic microwave background is sufficient to constrain the curvature of the Universe to Omega_k = 0.0010 +- 0.0029, the total neutrino mass to Sum m_nu < 0.23 eV (95% confidence level), the effective number of relativistic species to N_eff=3.31 +- 0.27, and the dark energy equation of state to w_DE = -1.051 +- 0.076. These limits are further improved by adding information from type Ia supernovae and baryon acoustic oscillations from other samples. In particular, this data set combination is completely consistent with a time-independent dark energy equation of state, in which case we find w_DE=-1.024 +- 0.052. We explore the constraints on the growth-rate of cosmic structures assuming f(z)=Omega_m(z)^gamma and obtain gamma=0.69 +- 0.15, in agreement with the predictions from general relativity of gamma=0.55.

Figures (14)

• Figure 1: Angle-averaged correlation functions $\xi(s)$, (left panels) and clustering wedges $\xi_{\perp}(s)$ and $\xi_{\parallel}(s)$ (right panels) of the LOWZ and CMASS DR10 galaxy samples. The error bars were derived from the diagonal entries of the full covariance matrices obtained as described in Sec. \ref{['sec:covariance']}. The dashed lines correspond to the best-fitting $\Lambda$CDM model obtained from the combination of information from the full shape of the LOWZ and CMASS DR11 clustering wedges with the CMB temperature fluctuation measurements from Planck and the nine-year polarization measurements from WMAP (see Section \ref{['sec:lcdm']}).
• Figure 2: The same as Figure 1, but for the LOWZ and CMASS DR11 galaxy samples.
• Figure 3: Two-dimensional marginalized constraints in the $D_{\rm A}(z_{\rm m})\left(r_{\rm d}^{\rm fid}/r_{\rm d}\right)$--$H(z_{\rm m})\left(r_{\rm d}/r_{\rm d}^{\rm fid}\right)$ plane at $z_{\rm m}=0.32$ (left panel) and $z_{\rm m}=0.57$ (right panel) derived from the LOWZ and CMASS DR11 samples, respectively. The grey long-dashed contours show the results obtained using information from the angle-averaged correlation function while the red solid lines correspond to those inferred from the clustering wedges $\xi_{\perp}(s)$ and $\xi_{\parallel}(s)$ assuming that $f(z)$ follows the predictions of GR. The short-dashed contours correspond to the prediction for these parameters derived from the ePlanck data set (see Section \ref{['sec:moredata']}) under the assumption of a $\Lambda$CDM model.
• Figure 4: Two-dimensional marginalized constraints in the $\Omega_{\rm m}$--$h$ plane. The blue dashed lines correspond to the constraints from the Planck (upper panel) and WMAP9 (lower panel) CMB measurements, which follow a degeneracy of constant $\Omega_{\rm m}h^3$, as indicated by the dotted lines. The red solid lines show the results obtained when these measurements are combined with the information from the LOWZ and CMASS DR11 clustering wedges.
• Figure 5: Left panel: marginalized 68 and 95 per cent CL in the $\Omega_{\rm m}$--$w_{\rm DE}$ plane for the $\Lambda$CDM parameter set extended by including the redshift-independent value of $w_{\rm DE}$ as an additional parameter. The contours correspond to the results obtained using the WMAP9-only (blue long-dashed lines), the WMAP9+BOSS $\xi(s)$ combination (grey short-dashed lines) and the WMAP9+BOSS $\xi_{\Delta \mu}(s)$ case (red solid lines). The right panel shows the results obtained when the WMAP9 measurements are replaced by the Planck CMB data set. The dotted line in both panels corresponds to the $\Lambda$CDM model value of $w_{\rm DE}=-1$.