Gravitational shear, flexion and strong lensing in Abell 1689

The Astrophysical Journal, 666(1): pp. 51-63.We present a gravitational lensing analysis of the galaxy cluster Abell 1689, incorporating measurements of the weak shear, exion, and strong lensing induced in background galaxies. This is the first time that a shapelet technique has been used to reconstruct the distribution of mass in this cluster, and the first time that a exion signal has been measured using cluster members as lenses. From weak shear measurements alone, we generate a non-parametric mass reconstruction, which shows signifcant substructure corresponding to groups of galaxies within the cluster. Additionally, our galaxy-galaxy exion signal demonstrates that the cluster galaxies can be well-t by a singular isothermal sphere model with a characteristic velocity dispersion of Ov = 295 +/- 40 km=s. We identify a major, distinct dark matter clump, offset by 40h-1kpc from the central cluster members, which was not apparent from shear measurements alone. This secondary clump is present in a parametric mass reconstruction using exion data alone, and its existence is suggested in a non-parametric reconstruction of the cluster using a combination of strong and weak lensing. As found in previous studies, the mass profile obtained by combining weak and strong lensing data shows a much steeper profile than that obtained from only weak lensing data