Large-scale galaxy distribution in the Las Campanas Redshift Survey

We make use of three-dimensional clustering analysis, inertia tensor method s, and the minimal spanning tree, technique to estimate some physical and s tatistical characteristics of the large-scale galaxy distribution and, in p articular, of the sample of overdense regions seen in the Las Campanas Reds hift Survey (LCRS). Our investigation provides additional evidence for a ne twork of structures found in our core sampling analysis of the LCRS: a syst em of rich sheet-like structures, which in turn surround large underdense r egions criss-crossed by a variety of filamentary structures. We find that the overdense regions contain similar to 40-50 per cent of LCR S galaxies and have proper sizes similar to those of nearby superclusters. The formation of such structures can be roughly described as a non-linear c ompression of protowalls of typical cross-sectional size similar to 20-25 h (-1) Mpc; this scale is similar to5 times the conventional value for the on set of non-linear clustering - to wit, r(0), the autocorrelation length for galaxies. The comparison with available simulations and theoretical estimates shows t hat the formation of structure elements with parameters similar to those ob served is presently possible only in low-density cosmological models, Omega (m)h similar to 0.2-0.3, with a suitable large-scale bias between galaxies and dark matter.