New highly precise weak gravitational lensing flexions measurement method based on ERA method

TL;DR

This paper introduces a new highly precise method for measuring weak gravitational lensing flexions using the ERA method, which improves accuracy by eliminating intrinsic noise through specific combinations of flexion signals.

Contribution

The paper presents a novel measurement technique for flexions based on the ERA method, enabling noise-free extraction of lensing information and enhancing observational cosmology capabilities.

Findings

The new method accurately measures flexions with reduced noise.

Numerical simulations confirm independence from intrinsic distortions.

The approach improves sensitivity to local mass distribution.

Abstract

Weak gravitational lensing flexions are a kind of weak lensing distortion which are defined as the spin 1 and spin 3 combinations of the third order derivatives of gravitational lensing potential. Since the shear has spin 2 combination of the second order derivative, the flexion signal gives a partly independent information from shear signal and is more sensitive to the local mass distribution than shear signal. Thus its measurement is expected to play important roles in observational cosmology. However, since the weakness of the flexion signal as well as the complicatedness of its intrinsic noise made its accurate observation very difficult. We propose a new method of measuring the flexion signal using ERA method which is a method to measure weak lensing shear without any approximation. We find two particular combinations of the flexions which provide the quantities with only lensing information and free of intrinsic noise when taken average. It is confirmed by simple numerical simulation that the statistical average of these combinations do not in fact depend on the strength of the intrinsic distortion.