Cosmological Tests using Redshift Space Clustering in BOSS DR11

TL;DR

This paper uses large-scale galaxy clustering data from BOSS DR11 to measure cosmological parameters, confirming consistency with LCDM and general relativity, while exploring potential anisotropic effects.

Contribution

It provides a model-independent analysis of anisotropic clustering, robustly measuring H, D_A, and G_T at z=0.57 using large galaxy samples and small-scale clustering cuts.

Findings

Results agree with LCDM and general relativity within 68% CL

Identifies slight tension in growth rate between hemispheres

Robust measurements achieved by excluding small-scale data

Abstract

We analyze the clustering of large scale structure in the Universe in a model independent method, accounting for anisotropic effects along and transverse to the line of sight. The Baryon Oscillation Spectroscopy Survey Data Release 11 provides a large sample of 690,000 galaxies, allowing determination of the Hubble expansion H, angular distance D_A, and growth rate G_T at an effective redshift of z=0.57. After careful bias and convergence studies of the effects from small scale clustering, we find that cutting transverse separations below 40 Mpc/h delivers robust results while smaller scale data leads to a bias due to unmodelled nonlinear and velocity effects. The converged results are in agreement with concordance LCDM cosmology, general relativity, and minimal neutrino mass, all within the 68% confidence level. We also present results separately for the northern and southern hemisphere sky, finding a slight tension in the growth rate -- potentially a signature of anisotropic stress, or just covariance with small scale velocities -- but within 68% CL.