Cosmological Constraints from a Combination of Galaxy Clustering and Lensing -- III. Application to SDSS Data

TL;DR

This paper combines galaxy clustering and lensing data from SDSS to tightly constrain cosmological parameters, demonstrating consistency with the standard { extLambda}CDM model using advanced galaxy bias modeling.

Contribution

It introduces a comprehensive method using the conditional luminosity function and halo model to accurately connect galaxy observations with underlying dark matter, improving cosmological constraints.

Findings

Measured { extOmega}m = 0.278_{-0.026}^{+0.023}

Measured { extsigma}8 = 0.763_{-0.049}^{+0.064}

Results agree with WMAP7 CMB constraints

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 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 {\Lambda}CDM cosmology, we focus on constraining the matter density, {\Omega}m, and the normalization of the matter power spectrum, {\sigma}8, and we adopt WMAP7 priors for the spectral index, the Hubble parameter, and the baryon density. We obtain that \Omegam = 0.278_{-0.026}^{+0.023} and {\sigma}8 = 0.763_{-0.049}^{+0.064} (95% 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 {\sigma}8 (0.744_{-0.047}^{+0.056}). These constraints are in excellent agreement (at the 1{\sigma} 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 {\Lambda}CDM cosmology.