COLD DARK-MATTER MODELS WITH A COSMOLOGICAL CONSTANT

We use linear and quasi-linear perturbation theory to analyse cold dar k matter models of structure formation in spatially flat models with a cosmological constant. Both a tilted spectrum of density perturbation s and a significant gravitational wave contribution to the microwave a nisotropy are allowed as possibilities. We provide normalizations of t he models to microwave anisotropies, as given by the four-year COBE ob servations, and show how all the normalization information for such mo dels, including tilt, can be condensed into a single fitting function which is independent of the value of the Hubble parameter, We then dis cuss a wide variety of other types of observations. We find that a ver y wide parameter space is available for these models, provided Omega(0 ) is greater than about 0.3, and that large-scale structure observatio ns show no preference for any particular value of Omega(0) in the rang e 0.3 to 1.