Spin-SILC: CMB polarisation component separation with spin wavelets

Abstract

We present Spin-SILC, a new foreground component separation method that accurately extracts the cosmic microwave background (CMB) polarisation $E$ and $B$ modes from raw multifrequency Stokes $Q$ and $U$ measurements of the microwave sky. Spin-SILC is an internal linear combination method that uses spin wavelets to analyse the spin-2 polarisation signal $P=Q+iU$. The wavelets are additionally directional (non-axisymmetric). This allows different morphologies of signals to be separated and therefore the cleaning algorithm is localised using an additional domain of information. The advantage of spin wavelets over standard scalar wavelets is to simultaneously and self-consistently probe scales and directions in the polarisation signal $P=Q+iU$ and in the underlying $E$ and $B$ modes, therefore providing the ability to perform component separation and $E$-$B$ decomposition concurrently for the first time. We test Spin-SILC on full-mission Planck simulations and data and show the capacity to correctly recover the underlying cosmological $E$ and $B$ modes. We also demonstrate a strong consistency of our CMB maps with those derived from existing component separation methods. Spin-SILC can be combined with the pseudo- and pure $E$-$B$ spin wavelet estimators presented in a companion paper to reliably extract the cosmological signal in the presence of complicated sky cuts and noise. Therefore, it will provide a computationally-efficient method to accurately extract the CMB $E$ and $B$ modes for future polarisation experiments.

13 pages, 9 figures. Minor changes to match version published in MNRAS. Map products available at http://www.silc-cmb.org. Companion paper: arXiv:1605.01414 "Wavelet reconstruction of pure E and B modes for CMB polarisation and cosmic shear analyses" (B. Leistedt et al.)

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• Wiener filtering and pure E/B decomposition of CMB maps with anisotropic correlated noise
• An Improved Diffuse Foreground Subtraction by ILC method: CMB Map and Angular Power Spectrum using Planck and WMAP Observations
• Pure E and B polarization maps via Wiener filtering
• Constraints on non-resonant photon-axion conversion from the Planck satellite data
• Sparse image reconstruction on the sphere: analysis and synthesis
• Efficient ILC analysis on polarization maps after EB leakage correction
• A Novel CMB Component Separation Method: Hierarchical Generalized Morphological Component Analysis
• Optimal and fast E/B separation with a dual messenger field
• Scattering Networks on the Sphere for Scalable and Rotationally Equivariant Spherical CNNs
• Needlet estimation of cross-correlation between CMB lensing maps and LSS