Measurement of halo properties with weak lensing shear and flexion

TL;DR

This paper demonstrates that combining weak lensing shear and flexion data enhances the accuracy of measuring galaxy cluster halo properties, especially ellipticity and orientation, by breaking degeneracies present in shear-only analyses.

Contribution

It introduces a likelihood analysis method that incorporates both shear and flexion data, improving constraints on halo ellipticity, orientation, and mass in simulated cluster models.

Findings

Flexion is more sensitive to halo ellipticity than shear.

Including flexion significantly improves parameter constraints.

Degeneracy exists between mass and ellipticity in shear-only models.

Abstract

We constrain properties of cluster haloes by performing likelihood analysis using lensing shear and flexion data. We test our analysis using two mock cluster haloes: an isothermal ellipsoid (SIE) model and a more realistic elliptical Navarro-Frenk-White (eNFW) model. For both haloes, we find that flexion is more sensitive to the halo ellipticity than shear. The introduction of flexion information significantly improves the constraints on halo ellipticity, orientation and mass. We also point out that there is a degeneracy between the mass and the ellipticity of SIE models in the lensing signal.