We have derived detailed R band luminosity profiles and structural parameters for a total of 430 brightest cluster galaxies (BCGs), down to a limiting surface brightness of 24.5 magarcsec −2 . Light profiles were initially fitted with a Sérsic's R 1/n model, but we found that 205 (∼ 48%) BCGs require a double component model to accurately match their light profiles. The best fit for these 205 galaxies is an inner Sérsic model, with indices n ∼ 1 − 7, plus an outer exponential component.Thus, we establish the existence of two categories of the BCGs luminosity profiles: single and double component profiles. We found that double profile BCGs are brighter (∼ 0.2 mag) than single profile BCG. In fact, the Kolmogorov-Smirnov test applied to these subsamples indicates that they have different total magnitude distributions, with mean values M R = −23.8 ± 0.6 mag for single profile BCGs and M R = −24.0 ± 0.5 mag for double profile BCGs. We find that partial luminosities for both subsamples are indistinguishable up to r = 15 kpc, while for r > 20 kpc the luminosities we obtain are on average 0.2 mag brighter for double profile BCGs. This result indicates that extra-light for double profile BCGs does not come from the inner region but from the outer regions of these galaxies.The best fit slope of the Kormendy relation for the whole sample is a = 3.13 ± 0.04. However, when fitted separately, single and double profile BCGs show different slopes: a single = 3.29 ± 0.06 and a double = 2.79 ± 0.08. Also, the logarithmic slope of the metric luminosity α is higher in double profile BCGs (α double = 0.65 ± 0.12) than in single profile BCGs (α single = 0.59 ± 0.14). The mean isophote outer ellipticity (calculated at µ ∼ 24 mag arcsec −2 ) is higher in double profile BCGs (e double = 0.30 ± 0.10) than in single profile BCGs (e single = 0.26 ± 0.11). Similarly, the mean absolute value of inner minus outer ellipticity is also higher in double profile BCGs On the other hand, we did not find differences between these two BCGs categories when we compared global cluster properties such as the BCG-projected position relative to the cluster X-ray center emission, X-ray luminosity, or BCG orientation with respect to the cluster position angle.

We present results of our wide-field redshift survey of galaxies in a 285 square degree region of the Shapley Supercluster (SSC), based on a set of 10 529 velocity measurements (including 1201 new ones) on 8632 galaxies obtained from various telescopes and from the literature. Our data reveal that the main plane of the SSC (v ≈ 14 500 km s −1 ) extends further than previous estimates, filling the whole extent of our survey region of 12 degrees by 30 degrees on the sky (30 × 75 h −1 Mpc). There is also a connecting structure associated with the slightly nearer Abell 3571 cluster complex (v ≈ 12 000 km s −1 ). These galaxies seem to link two previously identified sheets of galaxies and establish a connection with a third one at v = 15 000 km s −1 near RA = 13 h . They also tend to fill the gap of galaxies between the foreground Hydra-Centaurus region and the more distant SSC. In the velocity range of the Shapley Supercluster (9000 km s −1 < cz < 18 000 km s −1 ), we found redshift-space overdensities with b j < 17.5 of 5.4 over the 225 square degree central region and 3.8 in a 192 square degree region excluding rich clusters. Over the large region of our survey, we find that the intercluster galaxies make up 48 per cent of the observed galaxies in the SSC region and, accounting for the different completeness, may contribute nearly twice as much mass as the cluster galaxies. In this paper, we discuss the completeness of the velocity catalogue, the morphology of the supercluster, the global overdensity, and some properties of the individual galaxy clusters in the Supercluster.

We perform a comparative analysis of the properties of galaxies infalling into groups classifying them accordingly to whether they are: falling along filamentary structures; or they are falling isotropically. For this purpose, we identify filamentary structures connecting massive groups of galaxies in the SDSS. We perform a comparative analysis of some properties of galaxies in filaments, in the isotropic infall region, in the field, and in groups. We study the luminosity functions (LF) and the dependence of the specific star formation rate (SSFR) on stellar mass, galaxy type, and projected distance to the groups that define the filaments. We find that the LF of galaxies in filaments and in the isotropic infalling region are basically indistinguishable between them, with the possible exception of late-type galaxies. On the other hard, regardless of galaxy type, their LFs are clearly different from that of field or group galaxies. Both of them have characteristic absolute magnitudes and faint end slopes in between the field and group values. More significant differences between galaxies in filaments and in the isotropic infall region are observed when we analyse the SSFR. We find that galaxies in filaments have a systematically higher fraction of galaxies with low SSFR as a function of both, stellar mass and distance to the groups, indicating a stronger quenching of the star formation in the filaments compared to both, the isotropic infalling region, and the field. Our results suggest that some physical mechanisms that determine the differences observed between field galaxies and galaxies in systems, affect galaxies even when they are not yet within the systems.