CMB B-polarization to map the Large-scale Structures of the Universe

Abstract

We explore the possibility of using the B-type polarization of the CMB to map the large-scale structures of the Universe taking advantage of the lens effects on the CMB polarization. The functional relation between the B component with the primordial CMB polarization and the line-of-sight mass distribution is explicited. Noting that a sizeable fraction (at least 40%) of the dark halo population which is responsible of this effect can also be detected in galaxy weak lensing survey, we present statistical quantities that should exhibit a strong sensitivity to this overlapping. We stress that it would be a sound test of the gravitational instability picture, independent on many systematic effects that may hamper lensing detection in CMB or galaxy survey alone. Moreover we estimate the intrinsic cosmic variance of the amplitude of this effect to be less than 8% for a 100, deg^2 survey with a 10' CMB beam. Its measurement would then provide us with an original mean for constraining the cosmological parameters, more particularly, as it turns out, the cosmological constant Lambda.