DO THE REDSHIFTS OF GRAVITATIONAL LENS GALAXIES RULE OUT A LARGE COSMOLOGICAL CONSTANT

The distribution of lens galaxy redshifts in known gravitational lens systems is an extremely powerful means of discriminating between some cosmologies. Standard cosmologies are 5-10 times more probable than flat large cosmological constant cosmologies with lambda-0 greater-than-or-similar-to 0.9 based on the existing small sample. A few additional gravitational lens systems produced by isolated galaxies with known source and lens redshifts would settle the question, because the probability of the redshift distribution in an Einstein-de Sitter universe agreeing with the flat, lambda-0 greater-than-or-similar-to 0.9 models drops faster than is-proportional-to (0.5)N, where N is the number of systems. The uncertainties in the mass distribution of galaxies are larger than the differences between standard FRW OMEGA-0 = 0 to OMEGA-0 = 1 models. If we confine ourselves to Einstein-de Sitter cosmologies, we can predict redshifts for several of the lenses in which they are not currently known. If we model the lens galaxies as ellipticals, then the predicted redshifts of the lens galaxy for the gravitational lenses PG 1115 + 080 and 1413 + 117 are z(L) = 0.37 +/- 0.18 (0.48 +/- 0.22) and z(L) = 0.68 +/- 0.33, (0.92 +/- 0.40) where the errors correspond to one standard deviation in the redshift probability distribution, and the two sets of ranges correspond to sigma-m = sigma or sigma-m = (3/2)1/2-sigma, where sigma-m is the velocity dispersion characteristic of the mass distribution, and sigma is the measured velocity dispersion.