Constraints on Omega(Lambda) and Omega(m) from distant Type Ia supernovae and cosmic microwave background anisotropies

We perform a combined likelihood analysis of the latest cosmic microwave ba ckground anisotropy data and distant Type Ia supernova data of Perlmutter e t al. bur analysis is restricted to cosmological models where structure for ms from adiabatic initial fluctuations characterized by a power-law spectru m with negligible tensor component. Marginalizing over other parameters, ou r best-fitting solution gives Omega(m) = 0.25(-0.12)(+0.18) and Omega(Lambd a) = 0.63(-0.23)(+0.18) (95 per cent confidence errors) for the cosmic dens ities contributed by matter and a cosmological constant, respectively. The results therefore strongly favour a nearly spatially flat Universe with a n onzero cosmological constant.