Cross-Correlation Tomography: Measuring Dark Energy Evolution with Weak Lensing

A cross-correlation technique of lensing tomography is developed to probe dark energy in the Universe. The variation of weak shear with redshift around foreground galaxies depends only on the angular distances and is robust to the dominant systematic error in lensing. We estimate the marginalized accuracies that deep lensing surveys with photometric redshifts can provide on the dark energy density Ωde, the equation of state parameter w, and its evolution w^': σ(w)0.01fsky^-1/2 and σ(w^')0.03fsky^-1/2, where a prior of σ(Ωde)=0.03 is assumed in the marginalization.