Measurement of halo properties with weak lensing shear and flexion
  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.
