Shear Power Spectrum Reconstruction using Pseudo-Spectrum Method

TL;DR

This paper introduces a pseudo-spectrum method for accurately reconstructing the lensing power spectrum from weak lensing surveys, effectively handling masked regions and complex survey geometries.

Contribution

The paper presents a novel pseudo power spectrum technique that improves lensing power spectrum measurement accuracy in the presence of survey masks and boundaries.

Findings

Achieves sub-percent precision in E-mode power spectrum recovery

Residual B-mode contamination is suppressed below one percent

Systematic errors are smaller than statistical errors for large surveys

Abstract

We develop a pseudo power spectrum technique for measuring the lensing power spectrum from weak lensing surveys in both the full sky and flat sky limits. The power spectrum approaches have a number of advantages over the traditional correlation function approach. We test the pseudo spectrum method by using numerical simulations with square-shape boundary that include masked regions with complex configuration due to bright stars and saturated spikes. Even when 25% of total area of the survey is masked, the method recovers the E-mode power spectrum at a sub-percent precision over a wide range of multipoles 100<l<10000. The systematic error is smaller than the statistical errors expected for a 2000 square degree survey. The residual B-mode spectrum is well suppressed in the amplitudes at less than a percent level relative to the E-mode. We also find that the correlated errors of binned power spectra caused by the survey geometry effects are not significant. Our method is applicable to the current and upcoming wide-field lensing surveys.