Las Campanas Loose Groups in the supercluster-void network

¹ Tartu Observatory, 61602 Tõravere, Estonia
² Institute of Physics, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia
³ Tuorla Observatory, Väisäläntie 20, Piikkiö, Finland
⁴ Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
⁵ Fermi National Accelerator Laboratory, MS 127, PO Box 500, Batavia, IL 60510, USA

Corresponding author: M. Einasto, maret@aai.ee

Received: 23 January 2003
Accepted: 17 April 2003

Abstract

We study the spatial distribution of loose groups from the Las Campanas Redshift Survey, comparing it with the supercluster-void network delineated by rich clusters of galaxies. We use density fields and the friends-of-friends (FoF) algorithm to identify the members of superclusters of Abell clusters among the Las Campanas loose groups. We find that systems of loose groups tend to be oriented perpendicularly to the line-of-sight, and discuss possible reasons for that. We show that loose groups in richer systems (superclusters of Abell clusters) are themselves also richer and more massive than groups in systems without Abell clusters. Our results indicate that superclusters, as high density environments, have a major role in the formation and evolution of galaxy systems.