Probing decisive answers to dark energy questions from cosmic complementarity and lensing tomography

We study future constraints on dark energy parameters determined from several combinations of cosmic microwave background experiments, supernova data, and cosmic shear surveys with and without tomography. In this analysis, we look in particular for combinations of experiments that will bring the uncertainties to a level of precision tight enough (a few percent) to answer decisively some of the dark energy questions. In view of the parameterization dependence problems, we probe the dark energy using two variants of its equation of state w(z), and its energy density ρde(z). For the latter, we model ρde(z) as a continuous function interpolated using dimensionless parameters Ei(zi) ≡ ρde(zi)/ρde(0). We consider a large set of 13 cosmological and systematic parameters, and assume reasonable priors on the lensing and supernova systematics. For CMB, we consider future constraints from 8 years of data from WMAP, one year of data from Planck, and one year of data from the Atacama Cosmology Telescope (ACT). We use two sets of 2000 supernovae with zmax = 0.8 and 1.5 respectively, and consider various cosmic shear reference surveys: a wide ground-based like survey, covering 70 % of the sky, and with successively 2 and 5 tomographic bins; a deep spacebased like survey with 10 tomographic bins and various sky coverages. The one sigma