The ERA Method with Idealizing PSF for Precise Weak Gravitational Lensing Shear Analysis

TL;DR

This paper extends the ERA method for PSF correction in weak gravitational lensing, making it applicable to complex PSF shapes and analyzing the impact of pixel noise on shear measurement accuracy.

Contribution

The paper introduces a generalized ERA method using an idealized PSF for arbitrary PSF shapes, improving shear analysis accuracy in weak lensing.

Findings

The generalized ERA method effectively handles complex PSF shapes.

Pixel noise causes systematic overestimation in shear measurements.

The method avoids errors from traditional PSF correction approximations.

Abstract

We generalize ERA method of PSF correction for more realistic situations. The method re-smears the observed galaxy image(galaxy image smeared by PSF) and PSF image by an appropriate function called Re-Smearing Function(RSF) to make new images which have the same ellipticity with the lensed (before smeared by PSF) galaxy image. It has been shown that the method avoids a systematic error arising from an approximation in the usual PSF correction in moment method such as KSB for simple PSF shape. By adopting an idealized PSF we generalize ERA method applicable for arbitrary PSF. This is confirmed with simulated complex PSF shapes. We also consider the effect of pixel noise and found that the effect causes systematic overestimation.