Detectability of CMB tensor B modes via delensing with weak lensing galaxy surveys

Understand

We analyze the possibility of delensing CMB polarization maps using foreground weak lensing (WL) information.

• We build an estimator of the CMB lensing potential out of optimally combined projected potential estimators to different source redshift bins.
• Our estimator is most sensitive to the redshift depth of the WL survey, less so to the shape noise level.
• Estimators built using galaxy surveys like LSST and SNAP yield a 30-50% reduction in the lensing B-mode power.