Fig. 1. Galaxies in the sample PPS2: 4+1 diagram, i.e. 4 sections

1 Fig. 1. Galaxies in the sample PPS2: 4+1 diagram, i.e. 4 sections of (α, δ, cz; M Z) space + 1 redshift distribution histogram. Each dot is a galaxy. The redshift scale is the same everywhere. Top left: red-shift space, δ–cz wedge diagram. Top right: sky–view, α–δ diagram. Bottom right: redshift space, α–cz wedge diagram. Bottom left: dis-tance–luminosity diagram in the cz–M Z plane (the lower envelope is the faint cut–off m lim = 15.5), and distance (redshift) distribution histogram (the normalization is arbitrary). Fig. 2. Dependence of group properties (medians) from the FOF normalizations. (a) the l.o.s. velocity dispersion σv vs the red-shift link V 0 (D 0 = 0.231 h −1 Mpc); (b) the harmonic mean radius R h , and the pairwise mean separation Rp vs the spatial link D 0 (V 0 = 350 km s −1). Symbols are explained in the Figure. The straight lines are linearly fitted to the data of the PPS2 groups only. The bars are ±1 standard deviation divided by √ N G. Such bars have not been used in the linear fit to the medians. They are only shown in order to give an idea of the typical dispersions of group properties around their central values. We also show data for the CfA2N groups of Ramella et al. (1997; their Fig. 1), and for PPS2 groups selected with D 0 = 0.270 h −1 Mpc and variable V 0. Fig. 3. Members of loose groups in PPS2: 4+1 diagram. Each dot is a group member galaxy. Everything else as in Fig. 1. Fig. 4. Loose Groups in PPS2: 4+1 diagram. Each dot is a group (number–weighted centroid, Nmem ≥ 3 member galaxies). The group magnitude is computed by adding up the luminosity of all observed group members, and the lower envelope corresponds to 3 member galaxies of magnitude m lim = 15.5. Everything else as in Fig. 1. Fig. 5. Radial distribution of groups and galaxies in PPS2. Red-shift distribution for groups (thick histogram), group members (thin dashed histogram), and all galaxies (thin dotted histogram). For comparison, all curves are normalized to the same total area 2 Fig. 6. Internal properties X of loose groups in PPS2. Left panels: distribution histogram dN (X). Right panels: variation with distance. Here we have: (a,b) X = Nmem; (c,d) X = log 10 (L G /L ⊙). The curves are not fitted …