The VIMOS-VLT deep survey: the group catalogue

We present a homogeneous and complete catalogue of optical galaxy groups identified in the VIMOS-VLT spectroscopic Deep Survey (VVDS). We use mock catalogues extracted from the Millennium simulation to study the potential systematics that might affect the overall distribution of the identified systems, and also to asses how well galaxy redshifts trace the line-of-sight velocity dispersion of the underlying mass overdensity. We train on these mock catalogues the adopted group-finding technique (the Voronoi-Delaunay Method, VDM), to recover in a robust and unbiased way the redshift and velocity dispersion distributions of groups and maximise the level of completeness (C) and purity (P) of the group catalogue. We identify 318(/144) VVDS groups with at least 2(/3) members within 0.2