Definitive Identification of the Transition between Small- to Large-Scale Clustering for Lyman Break Galaxies

Abstract

We report angular correlation function (ACF) of Lyman Break Galaxies (LBGs) with unprecedented statistical quality on the basis of 16,920 LBGs at z=4 detected in the 1 deg^2 sky of the Subaru/XMM-Newton Deep Field. The ACF significantly departs from a power law, and shows an excess on small scale. Particularly, the ACF of LBGs with i&#39;<27.5 have a clear break between the small and large-scale regimes at the angular separation of ~7&#39;&#39; whose projected length corresponds to the virial radius of dark halos with a mass of 10^11-12 Mo, indicating multiple LBGs residing in a single dark halo. Both on small (2&#39;&#39;<theta<3&#39;&#39;) and large (40&#39;&#39;<theta<400&#39;&#39;) scales, clustering amplitudes monotonically increase with luminosity for the magnitude range of i&#39;=24.5-27.5, and the small-scale clustering shows a stronger luminosity dependence than the large-scale clustering. The small-scale bias reaches b~10-50, and the outskirts of small-scale excess extend to a larger angular separation for brighter LBGs. The ACF and number density of LBGs can be explained by the cold dark matter model.