Non-parametric reconstruction of cluster mass distribution from strong lensing: modelling Abell 370.

Abstract

The authors describe a new non-parametric technique for reconstructing the mass distribution in galaxy clusters with strong lensing, i.e. from multiple images of background galaxies. The observed positions and redshifts of the images are considered as rigid constraints, and through the lens (ray-trace) equation they provide us with linear constraint equations. These constraints confine the mass distribution to some allowed region, which is then found by linear programming. Within this allowed region the authors study in detail the mass distribution with minimum mass-to-light variation, and also some other distributions, such as the smoothest mass distribution. The method is applied to the extensively studied cluster Abell 370, which hosts a giant luminous arc and several other multiply imaged background galaxies. The authors also present an estimate for the total mass of the central region of the cluster.