Effects of Systematic Uncertainties on the Supernova Determination of Cosmological Parameters

Mapping the recent expansion history of the universe offers the best hope for uncovering the characteristics of the dark energy believed to be responsible for the acceleration of the expansion. In determining cosmological and dark-energy parameters to the percent level, systematic uncertainties impose a floor on the accuracy more severe than the statistical measurement precision. We delineate the categorization, simulation, and understanding required to bound systematics for the specific case of the Type Ia supernova method. Using simulated data of forthcoming ground-based surveys and the proposed space-based SNAP mission we present Monte Carlo results for the residual uncertainties on the cosmological parameter determination. The tight systematics control with optical and near-infrared observations and the extended redshift reach allow a space survey to bound the systematics below 0.02 magnitudes at z = 1.7. For a typical SNAP-like supernova survey, this keeps total errors within 15% of the statistical values and provides estimation of Ωm to 0.03, w0 to 0.07, and w ′ to 0.3; these can be further improved by incorporating complementary data.