Cosmic tomographies: baryon acoustic oscillations and weak lensing

Abstract

We explore the complementarity between two tomographic probes of the universe: baryon acoustic oscillations (BAOs) and weak lensing (WL). We find that photometric measurements of BAOs alone do not provide very tight constraints on the dark energy equation of state parameters, partially due to our uncertain knowledge of the galaxy bias. WL, on the other hand, is adversely impacted by the uncertainties of the probability distribution of photometric redshift (photo-z) errors. A joint analysis of the two, however, is more robust to these uncertainties and leads to a remarkable improvement over the results of either probe alone. Forecasts of cosmological constraints are provided for various BAO and WL surveys in combination with CMB measurements from Planck. In particular, we find that the joint analysis of BAO and WL power spectra with the Large Synoptic Survey Telescope can tighten the errors of the dark energy equation of state (at a = 0.63) and its rate of change, respectively, to 0.016 and 0.16 (marginalized over 131 other parameters). With supernovae and cluster counting as well as higher-order statistics of the same galaxy and shear data, one can further improve the constraints.