A LIMIT ON THE COSMOLOGICAL CONSTANT

The fraction of galaxies which are merging is a rapidly increasing function of redshift, which for z less-than-or-similar-to 0.5 varies as (1 + z)m, where m is quite sensitive to both the density parameter, OMEGA, and the cosmological constant, LAMBDA. The index m has weak dependencies on the details of the mass and structure of the merging galaxies but does depend on the rate at which the mean velocity dispersion of the universe grows with time; however, these parameters are strongly constrained by current epoch observations. The current crude estimates of m from a variety of astronomical sources give m congruent-to 4.5 +/- 1. As a consequence, the current merger observations favor \LAMBDA\ less-than-or-similar-to 1.5H02, OMEGA = 1 +/- 0.5, in a zero curvature universe. The merger data is marginally incompatible with OMEGA = 0.1 and any LAMBDA. Forthcoming data on merging among moderate redshift galaxies will significantly reduce the uncertainty in the observational index m.