Systematic effects on lensing reconstruction from a patchwork of CMB polarization maps

TL;DR

This paper assesses how systematic errors in polarization maps affect gravitational lensing reconstruction in CMB studies, finding that accurate large-scale lensing potential reconstruction is feasible despite expected systematic residuals.

Contribution

It provides a numerical analysis of the impact of systematic errors on lensing reconstruction from patchwork polarization maps, highlighting robustness at near-future error levels.

Findings

Accurate large-scale lensing potential reconstruction is possible.

No severe degradation in delensing efficiency due to systematic residuals.

Systematic errors at expected levels do not significantly impair lensing analysis.

Abstract

We investigate the tolerance for systematic errors in lensing analysis applied to a patchwork map of Cosmic Microwave Background polarization. We focus on the properties of the individual polarization maps that comprise the patchwork and discuss the associated calibration residuals that are coherent on those subpatches. We numerically simulate the polarization field modulated as a whole patchwork and apply a suite of lensing analyses to reveal the response of the reconstructed gravitational lensing potential and delensing efficiency. At systematic error levels expected in the near future, we find that it is possible to accurately reconstruct the lensing potential on scales larger than the subpatch size and that there is no severe degradation of the lensing $B$-mode removal efficiency in the subsequent delensing analysis.