Cosmological constraints from a combination of galaxy clustering and lensing – III. Application to SDSS data

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Abstract
We simultaneously constrain cosmology and galaxy bias using measurements of galaxy abundances, galaxy clustering and galaxy–galaxy lensing taken from the Sloan Digital Sky Survey. We use the conditional luminosity function (which describes the halo occupation statistics as a function of galaxy luminosity) combined with the halo model (which describes the non-linear matter field in terms of its halo building blocks) to describe the galaxy–dark matter connection. We explicitly account for residual redshift-space distortions in the projected galaxy–galaxy correlation functions, and marginalize over uncertainties in the scale dependence of the halo bias and the detailed structure of dark matter haloes. Under the assumption of a spatially flat, vanilla Λ cold dark matter (ΛCDM) cosmology, we focus on constraining the matter density, Ωm, and the normalization of the matter power spectrum, σ8, and we adopt 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) priors for the spectral index, n, the Hubble parameter, h, and the baryon density, Ωb. We obtain that Ωm = 0.278+ 0.023− 0.026 and σ8 = 0.763+ 0.064− 0.049 (95 per cent CL). These results are robust to uncertainties in the radial number density distribution of satellite galaxies, while allowing for non-Poisson satellite occupation distributions results in a slightly lower value for σ8 (0.744+ 0.056− 0.047). These constraints are in excellent agreement (at the 1σ level) with the cosmic microwave background constraints from WMAP. This demonstrates that the use of a realistic and accurate model for galaxy bias, down to the smallest non-linear scales currently observed in galaxy surveys, leads to results perfectly consistent with the vanilla ΛCDM cosmology.
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