Checking BB purity in re-analysis for alternate masks

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October 26 2018, Clem Pryke

Recently we have been looking at results of sims run with more realistic Chile and Pole sky hit maps. See [1] [2] Sims_with_nominal_Chile_and_Pole_masks_II and Sims_with_nominal_Chile_and_Pole_masks.

The parametric re-analysis uses a pureB estimator from S2HAT as described in the intro to [3].

To check if this estimator is producing sufficient B-mode purity when run with the more realistic masks I added processing of the unlensed-LCDM maps to the pipeline through to power spectra. Since these contain zero input B-modes whatever BB power they show on output is due to E to B mixing. The plot below shows the results for the bandpowers we use in the re-analysis. Clearly the 04b mask performance in not as good and it probably needs more smoothing. However, note that in the first link above we don't actually see any greater bias on r for 04b than the other masks.

181026 f1.gif