The clustering of galaxies at z ≈ 0.5 in the SDSS-III Data Release 9 BOSS-CMASS sample: A test for the ACDM cosmology

Abstract

We present results on the clustering of 282 068 galaxies in theBaryon Oscillation Spectroscopic Survey (BOSS) sample of massive galaxies with redshifts 0.4 < z < 0.7 which is part of the Sloan Digital Sky Survey III project. Our results cover a large range of scales from ∼500 to ∼90 h-1 Mpc. We compare these estimates with the expectations of the flat A cold dark matter (ACDM) standard cosmological model with parameters compatible with Wilkinson Microwave Anisotropy Probe 7 data. We use the MultiDark cosmological simulation, one of the largest N-body runs presently available, together with a simple halo abundance matching technique, to estimate galaxy correlation functions, power spectra, abundance of subhaloes and galaxy biases. We find that the ACDM model gives a reasonable description to the observed correlation functions at z ≈ 0.5, which is remarkably good agreement considering that the model, once matched to the observed abundance of BOSS galaxies, does not have any free parameters. However, we find a ≥10 per cent deviation in the correlation functions for scales ≤ 1 and ∼10-40 h-1 Mpc. A more realistic abundance matching model and better statistics from upcoming observations are needed to clarify the situation. We also estimate that about 12 per cent of the 'galaxies' in the abundance-matched sample are satellites inhabiting central haloes with mass M ≥ 1014 h-1 M⊙. Using the MultiDark simulation, we also study the real-space halo bias b of the matched catalogue finding that b = 2.00 ± 0.07 at large scales, consistent with the one obtained using the measured BOSS-projected correlation function. Furthermore, the linear large-scale bias, defined using the extrapolated linear matter power spectrum, depends on the number density n of the abundance-matched sample as b=-0.048- (0.594 ± 0.02)log10(n/ h3 Mpc-3). Extrapolating these results to baryon acoustic oscillation scales, we measure a scale-dependent damping of the acoustic signal produced by non-linear evolution that leads to ∼2-4 per cent dips at ≥ 3s level for wavenumbers k ≥ 0.1 h Mpc-1 in the linear large-scale bias. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.