Optimizing blind reconstruction of CMB B-modes for future experiments

The detection of primordial polarization B modes of the Cosmic Microwave Background (CMB) requires exquisite control of Galactic foreground contamination. The Needlet Internal Linear Combination (NILC) method has proven effective in reconstructing CMB B modes without suffering from mis-modeling errors of Galactic emission. However, with the most complex foreground models, residual Galactic contamination from NILC is proved to bias, especially at large angular scales, the recovered CMB B modes from simulated data of future CMB experiments. We therefore present two new extensions of NILC, Multi-Clustering NILC (MC-NILC) and optimized constrained Moment ILC (ocMILC), which allow to enhance foreground subtraction in the reconstructed CMB signal.