Constraints on ΩΛ and Ωm from distant Type Ia supernovae and cosmic microwave background anisotropies

We perform a combined likelihood analysis of the latest cosmic microwave background anisotropy data and distant Type Ia supernova data of Perlmutter et al. bur analysis is restricted to cosmological models where structure forms from adiabatic initial fluctuations characterized by a power-law spectrum with negligible tensor component. Marginalizing over other parameters, our best-fitting solution gives Omega(m) = 0.25(-0.12)(+0.18) and Omega(Lambda) = 0.63(-0.23)(+0.18) (95 per cent confidence errors) for the cosmic densities contributed by matter and a cosmological constant, respectively. The results therefore strongly favour a nearly spatially flat Universe with a nonzero cosmological constant.