|Annu. Rev. Astron. Astrophys. 1988. 26:
Copyright © 1988 by . All rights reserved
Previous reviews of this topic include Tanaka & Ikeuchi (190) and Oort (128, pp. 408-9).
The distances of most quasars are much larger than the distances of galaxies and clusters of galaxies from which superclusters and voids have been detected in the large-scale structure. Shaver (180) discusses the possible existence of very large scale structure in the three-dimensional distribution of quasars, especially at redshifts z 0.5. Oort (127, 129) suggests that the redshift separation between known superclusters evolved back to z = 2.5 is of the same order as the separation between the strongest L absorption systems observed in quasars (cf. 170a), which suggests that the absorption systems may be caused by uncondensed Zel'dovich pancake gas (215, 215b, and Section 1.3) that has remained uncondensed. Detailed analyses of physical constraints for the gaseous clouds that are the L absorbers have been derived by, for example, Melott (117) and Ostriker & Ikeuchi (134), who discuss alternative models.