Exploring galaxy formation models and cosmologies with galaxy clustering

Using N-body simulations and galaxy formation models, we study the galaxy stellar mass correlation and the two-point autocorrelation. The simulations are run with cosmological parameters from the Wilkinson Microwave Anisotropy Probe (WMAP) first-, third- and seven-year results, which mainly differ in the perturbation amplitude of σ ₈. The stellar mass of galaxies is determined using either a semi-analytical galaxy formation model or a simple empirical abundance matching method. Compared to the Sloan Digital Sky Survey (SDSS) DR7 data at z= 0 and the DEEP2 results at z= 1, we find that the predicted galaxy clusterings from the semi-analytical model are higher than the data at small scales, regardless of the adopted cosmology. Conversely, the abundance matching method predicts good agreement with the data at both z= 0 and z= 1 for high-σ ₈ cosmologies (WMAP1 and WMAP7), but the predictions from a low-σ ₈ cosmology (WMAP3) are significantly lower than the data at z= 0. We find that the excess clustering at small scales in the semi-analytical model mainly arises from satellites in massive haloes, indicating that either the star formation is too efficient in low-mass haloes or tidal stripping is too inefficient at high redshift. Our results show that galaxy clustering is strongly affected by the models for galaxy formation, and thus can be used to constrain the baryonic physics. The weak dependence of galaxy clustering on cosmological parameters makes it difficult to constrain the WMAP1 and WMAP7 cosmologies.