Browsing by Author "Muriel, H"

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    Structure and dynamics of the Shapley Supercluster -: Velocity catalogue, general morphology and mass
    (2006) Proust, D; Quintana, H; Carrasco, ER; Reisenegger, A; Slezak, E; Muriel, H; Dünner, R; Sodre, L; Drinkwater, MJ; Parker, QA; Ragone, CJ
    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 approximate to 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 x 75 h(-1) Mpc). There is also a connecting structure associated with the slightly nearer Abell 3571 cluster complex (v approximate to 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 similar or equal to 5.4 over the 225 square degree central region and similar or equal to 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.
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    Velocity dispersions and cluster properties in the Southern Abell Redshift Survey clusters. II.
    (2002) Muriel, H; Quintana, H; Infante, L; Lambas, DG; Way, MJ
    We report an analysis of the dynamical structure of clusters of galaxies from a survey of photometric and spectroscopic observations in the fields of southern Abell clusters. We analyze the galaxy velocity field in extended regions up to 7 h(-1) Mpc from cluster centers, and we estimate mean velocity dispersions and their radial dependence. Only one from a total of 41 Abell clusters does not correspond to a dynamically bound system. However, four of these bound objects are double clusters. We estimate that 20% (seven clusters) of the 35 remaining are subject to serious projection effects. Normalizing the clustercentric distances by means of the overdensity radius r(200), and the velocity dispersion profiles (VDPs) by the corresponding mean cluster velocity dispersion, we computed the average VDP. Our results indicate a at behavior of the mean VDP at large distances from the cluster center. Nevertheless, we found that for the inner part of the clusters (r/r(200)less than or equal to1) the VDP is up to 10% smaller than at larger radii.