Astron. Astrophys. Suppl. Ser. 144, 323-347

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

K.Y. Stavrev

Send offprint request: K.Y. Stavrev

Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shosse Blvd., BG-1784 Sofia, Bulgaria
e-mail: kstavrev@skyarchive.org

Received July 22, 1999; accepted March 23, 2000

Abstract:

We present a mapping of the large voids ($D \geq$ 50 h^-1 Mpc) in the spatial distribution of clusters of galaxies in the Northern Galactic Hemisphere in a volume defined by galactic latitude $b \geq$ +30$^{\circ }$ and redshift $z \leq$ 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 identifies a void as a system of intersecting empty spheres is applied, allowing for a description of the void dimensions, volumes and shapes more complete than in previous investigations. A number of void catalogues corresponding to different tracer types, different sources of redshift data, and different 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 $R \geq$ 1 and $R \geq$ 0 Abell/ACO clusters are D_e = 105.0 $\pm$ 5.6 h^-1 Mpc and D_e = 87.2 $\pm$ 4.1 h^-1 Mpc, respectively, where D_e is the equivalent void diameter. We have identified the poor clusters, groups, and galaxies populating the voids of rich clusters and constructed radial density profiles of the voids, which show the presence of a void hierarchy.

Key words: cosmology: observations -- large-scale structure of Universe -- galaxies: clusters: general -- methods: data analysis