A study of the large voids in the spatial distribution of galaxy clusters in the Northern Galactic Hemisphere

Abstract

We present a mapping of the large voids (D 50 h 1 Mpc) in the spatial distribution of clusters of galaxies in the Northern Galactic Hemisphere in a vol- ume dened by galactic latitude b +30 and redshift z 0.14. Rich clusters with spectroscopically measured or photometrically estimated redshifts are used as tracers of the large-scale structure of the Universe. An automated void-search and analysis procedure which identies a void as a system of intersecting empty spheres is applied, al- lowing for a description of the void dimensions, volumes and shapes more complete than in previous investigations. A number of void catalogues corresponding to dierent tracer types, dierent sources of redshift data, and dier- ent versions of the search method have been generated and analysed. Visualizations of the 2-D and 3-D distributions of voids are presented. The estimated mean dimensions of the voids of R 1a ndR 0 Abell/ACO clusters are De = 105.0 5.6h 1 Mpc and De = 87.2 4.1h 1 Mpc, respectively, whereDe is the equivalent void diameter. We have identied the poor clusters, groups, and galaxies pop- ulating the voids of rich clusters and constructed radial density proles of the voids, which show the presence of a void hierarchy. studies of their properties (geometrical parameters, con- tent, environment) are of great importance for testing ba- sic assumptions in the contemporary theoretical models and scenarios of the formation and evolution of the LSS. One major complication in void studies arises from the diculty to obtain spatial distributions of the tracers of the LSS with spectroscopically measured redshifts which are fairly complete in volumes both wide and deep. From this point of view the use of rich clusters of galaxies as