Total halo mass as a function of the local density contrast computed in this work in different redshift bins (as in the labels) for galaxies with M_B ≤  − 20. The values of the density contrast are indicated as log (1 + δ) in the bottom x-axis and as δ in the top x-axis. The halo is the FOF halo in which the galaxy reside (the halo of the group/cluster of which the galaxy is member). Four top panels: Cmocks. Four bottom panels: Omocks. Red circles and contours refer to central galaxies, blue squares and contours to satellite galaxies. Each panel includes all the 23 mock samples. Lines represent the isodensity contours of all the galaxies in the panel. For clarity, single galaxies are plotted as small dots only outside the lowest density contour. Filled red circles (/blue squares) are the median values in density bins for central (/satellite) galaxies. The error bars represent the 16% and 84% of the halo mass distribution in each density bin. On the right vertical axis of each panel, we show the typical virial radius (in h^-1 Mpc) corresponding to the halo mass on the left vertical axis.