Spatial clustering in the ESO-Sculptor Survey: two-point correlation functions by galaxy type at redshifts 0.1 - 0.5

Abstract

We calculate the spatial two-point auto and cross-correlation functions for the 765 galaxies with Rc<21.5 and 0.1<z<0.51 in the ESO-Sculptor survey, and explore the segregation effects among the populations of giant (early-type, late spiral) and dwarf (dE, dI) galaxies. At separation of 0.3 h^-1 Mpc, pairs of early-type galaxies dominate the clustering over all the other types of pairs. At intermediate scales, 0.3-5 h^-1 Mpc, mixed pairs of dwarf and giant galaxies contribute equally as pairs of giant galaxies, whereas the latter dominate at ~10 h^-1 Mpc. We detect the signature of the transition between the 1-halo and 2-halo regimes which is expected in the scenario of galaxy formation by hierarchical merging of dark matter halos. The early-type galaxies largely outdo the late spiral galaxies in their 1-halo component, whereas the 2-halo components of both giant populations are comparable. The dwarf galaxies have an intermediate 1-halo component between the 2 giant galaxy types, and their 2-halo component is weak and consistent with null clustering. The present analysis indicates that the early-type galaxies are preferentially located near the centers of the most massive halos, whereas late spiral galaxies tend to occupy their outskirts or the centers of less massive halos. This analysis also unveils new results on the spatial distribution of dwarf galaxies: at the scale at which they significantly cluster inside the halos (<0.3 h^-1 Mpc), they are poorly mixed with the late spiral galaxies, and appear preferentially as satellites of early-type galaxies.