Galaxy formation at z ∼ 3: Constraints from spatial clustering

We use N-body simulations combined with semianalytic models to compute the clustering properties of modeled galaxies at z ∼ 3 and confront these predictions with the clustering properties of the observed population of Lyman break galaxies (LBGs). Several scenarios for the nature of LBGs are explored, which may be broadly categorized into models in which high-redshift star formation is driven by collisional starbursts and those in which quiescent star formation dominates. For each model, we make predictions for the LBG overdensity distribution, the variance of counts in cells, the correlation length, and close pair statistics. Models that assume a one-to-one relationship between massive dark matter halos and galaxies are disfavored by close pair statistics, as are models in which colliding halos are associated with galaxies in a simplified way. However, when modeling of gas consumption and star formation is included using a semianalytic treatment, the quiescent and collisional starburst models predict similar clustering properties and none of these models can be ruled out based on the available clustering data. None of the "realistic" models predict a strong dependence of clustering amplitude on the luminosity threshold of the sample, in apparent conflict with some observational results.