Full lensing analysis of Abell 1703: comparison of independent lens-modelling techniques

The inner mass profile of the relaxed cluster Abell 1703 is analysed by two very different strong-lensing techniques applied to the deep Advanced Camera for Surveys and the Wide Field Channel 3 imaging. Our parametric method has the accuracy required to reproduce many sets of multiple images, based on the assumption that mass approximately traces light. We test this assumption with a fully non-parametric, adaptive grid method, with no knowledge of the galaxy distribution. Differences between the methods are seen on fine scales due to member galaxies which must be included in models designed to search for lensed images, but on the larger scale the general distribution of dark matter is in good agreement, with very similar radial mass profiles. We add undiluted weak-lensing measurements from deep multicolour Subaru imaging to obtain a fully model-independent mass profile out to the virial radius and beyond. Consistency is found in the region of overlap between the weak and strong lensing, and the full mass profile is well described by a Navarro, Frenk & White (NFW) model of a concentration parameter, c_vir ~= 7.15 +/- 0.5 (and M_vir ~= 1.22 +/- 0.15 × 10¹⁵ M_solar h^-1). Abell 1703 lies above the standard c-M relation predicted for the standard Λ cold dark matter model, similar to other massive relaxed clusters with accurately determined lensing-based profiles.