Blind map level systematics cleaning: a quadratic estimator approach

We present the first detailed case study using quadratic estimators (QE) to diagnose and remove systematics present in observed Cosmic Microwave Background (CMB) maps. In this work we focus on the temperature to polarization leakage. We use an iterative QE analysis to remove systematics, in analogy to de-lensing, recovering the primordial B-mode signal and the systematic maps. We introduce a new Gaussian filtering scheme crucial to stable convergence of the iterative cleaning procedure and validate with comparisons to semi-analytical forecasts. We study the limitations of this method by examining its performance both on idealized simulations and on more realistic, non-ideal simulations, where we assume varying de-lensing efficiencies. Finally, we quantify the systematic cleaning efficiency by presenting a likelihood analysis on the tensor to scalar ratio, r, and demonstrate that the blind cleaning results in an un-biased measurement of r, reducing the systematic induced B-mode power by nearly two orders of magnitude.

Automated summary

This study presents a detailed case study using QE estimators to diagnose and remove systematics in observed CMB maps, focusing on temperature to polarization leakage. A new Gaussian filtering scheme is introduced for stable convergence of iterative cleaning process, and performance is evaluated on idealized and realistic simulations. Likelihood analysis demonstrates unbiased measurement of the tensor-to-scalar ratio, reducing systematic induced B-mode power significantly.