Joint cluster reconstructions: Combining free-form lensing and X-rays
  Galaxy clusters provide a multitude of observational data across wavelengths
and their structure and morphology are of considerable interest in cosmology as
well as astrophysics. We develop a framework that allows the combination of
lensing and non-lensing observations in a free-form and mesh-free approach to
infer the projected mass distribution of individual galaxy clusters. This
method can be used to test common assumptions on the morphology of clusters in
parametric models. We make use of the lensing reconstruction code SaWLens2 and
expand its capabilities by incorporating an estimate of the projected
gravitational potential based on X-ray data that are deprojected using the
local Richardson-Lucy method and used to infer the Newtonian potential of the
cluster and we discuss how potentially arising numerical artefacts can be
treated. We demonstrate the feasibility of our method on a simplified mock NFW
halo and on a cluster from a realistic hydrodynamical simulation and show how
the combination of X-ray and weak lensing data can affect a free-form
reconstruction, improving the accuracy in the central region in some cases by a
factor of two.
