CONSTRAINTS FROM HIGH-REDSHIFT SUPERNOVAE UPON SCALAR FIELD COSMOLOGIES

Recent observations of high-redshift type Ia supernovae have placed st ringent constraints on the cosmological constant Lambda. We explore th e implications of these SNe observations for cosmological models in wh ich a classically evolving scalar field currently dominates the energy density of the Universe. Such models have been shown to share the adv antages of Lambda models: compatibility with the spatial flatness pred icted by inflation; a Universe older than the standard Einstein-de Sit ter model; and, combined with cold dark matter, predictions for large- scale structure formation in good agreement with data from galaxy surv eys. Compared to the cosmological constant, these scalar field models are consistent with the SNe observations for a lower matter density, O mega(m0)similar to 0.2, and a higher age, H(0)t(0) greater than or sim ilar to 1. Combined with the fact that scalar field models imprint a d istinctive signature on the cosmic microwave background anisotropy, th ey remain currently viable and should be testable in the near future.