Removal of point source leakage from time-order data filtering

TL;DR

This paper introduces a new template fitting method to effectively remove point source leakage from CMB maps caused by filtering in ground-based experiments, improving the accuracy of primordial gravitational wave measurements.

Contribution

The paper presents a novel pixel-domain template fitting technique that reduces point source leakage without extensive time-domain data processing.

Findings

Effective leakage removal demonstrated in simulations

Improved accuracy in CMB polarization measurements

Method reduces computational time compared to traditional filtering

Abstract

Time-ordered data (TOD) from ground-based CMB experiments are generally filtered before map-making to remove or reduce the contamination from the ground and the atmospheric emissions. However, when the observation region contains strong point sources, the filtering process will result in considerable leakage around the point sources in a measured CMB map, and leave spurious polarization signals. Therefore, such signals need to be assessed and removed before CMB science exploitation. In this work, we present a new method that we call "template fitting" and can effectively remove these leakage signals in pixel domain, not only satisfying the requirement for measuring primordial gravitational waves from CMB-$B$ modes, but also avoiding time-consuming operations on TOD.