Supervoids are regions in the local Universe which do not contain rich clusters of galaxies. In order to investigate the distribution of galaxies in and around supervoids, we have studied the closest example, the Northern Local Void. It is defined as the region between the Local, Coma, and the Hercules superclusters, which is well covered by available redshift surveys. We find that this supervoid is not empty, but it contains small galaxy systems and poor clusters of galaxies. We study the cosmography of this void by analyzing the distribution of poor clusters of galaxies, elliptical and other galaxies in two projections. We present a catalogue of voids, defined by galaxies of different morphological type and luminosity, and analyze mean diameters of voids in different environments. This analysis shows that sizes of voids and properties of void walls are related. Voids defined by poor clusters of galaxies and by bright elliptical galaxies have a mean diameter of up to 40h^-1^Mpc. Faint late-type galaxies divide these voids into smaller voids. The faintest galaxies we can study are outlining voids with mean diameters of about 8h^-1^Mpc. Voids located in a high-density environment are smaller than voids in low-density regions. The dependence of void diameters on the type and luminosity of galaxies, as well as on the large-scale environment shows that voids form a hierarchical system.
Astronomy and Astrophysics
- Pub Date:
- September 1995
- COSMOLOGY: OBSERVATIONS;
- GALAXIES: CLUSTERING;
- LARGE-SCALE STRUCTURE OF THE UNIVERSE;
- 21 Pages, uuencoded postscript (text only) , postscript with all figures included is available on request or at http://www.uni-sw.gwdg.de/~ulindner/preprints.html or anonymous ftp at ftp://eden.uni-sw.gwdg.de/incoming/ulindner/nlv.ps.gz )