Real and Redshift-Space Clustering in the ESP Galaxy Redshift Survey

Abstract

We discuss the two-point correlation properties of galaxies in the ESO Slice Project (ESP) redshift survey, both in redshift and real space. The redshift-space correlation function xi(s) for the whole magnitude-limited survey is well described by a power law with \gamma ~ 1.55 between 3 and ~40/h Mpc, where it smoothly breaks down, crossing the zero value on scales as large as ~80/h Mpc. On smaller scales (0.2-2/h Mpc), the slope is shallower, mostly due to redshift-space depression by virialized structures. This effect is found to be enhanced by the J3 optimal-weighting estimator for xi. We explicitly evidence these effects by computing xi(r_p,pi) and the projected function w_p(r_p). In this way we recover the real-space correlation function xi(r), which we fit below 10/h Mpc with a power-law model. This gives a reasonable fit, with r_o=4.15^{+0.20}_{-0.21} /h Mpc and \gamma=1.67^{+0.07}_{-0.09}. This results on xi(r) and xi(s), and the comparison with other surveys, clearly confirm how the shape of spatial correlations above ~3/h Mpc is characterised by a significant `shoulder' with respect to the small-scale ~ -1.8 power law, corresponding to a steepening of P(k) near the turnover.