Shapley Supercluster Survey: mapping the dark matter distribution
  We present a 23deg$^2$ weak gravitational lensing survey of the Shapley
supercluster core and its surroundings using $gri$ VST images as part of the
Shapley Supercluster Survey (ShaSS). This study reveals the overall matter
distribution over a region containing 11 clusters at $z{\sim}0.048$ that are
all interconnected, as well as several ongoing cluster-cluster interactions.
Galaxy shapes have been measured by using the Kaiser-Squires-Broadhurst method
for the $g$- and $r$-band images and background galaxies were selected via the
$gri$ colour-colour diagram. This technique has allowed us to detect all of the
clusters, either in the $g$-band or $r$-band images, although at different
$\sigma$ levels, indicating that the underlying dark matter distribution is
tightly correlated with the number density of the member galaxies. The deeper
$r$-band images have traced the five interacting clusters in the supercluster
core as a single coherent structure, confirmed the presence of a filament
extending North from the core, and have revealed a background cluster at
$z{\sim}0.17$. We have measured the masses of the four richest clusters (A3556,
A3558, A3560 and A3562) in the two-dimensional shear pattern, assuming a
spherical Navarro-Frenk-White (NFW) profile and obtaining a total mass of
$\mathcal{M}_{\rm
  ShaSS,WL}{=}1.56^{+0.81}_{-0.55}{\times}10^{15\,}{\rm
  M}_{\odot}$, which is consistent with dynamical and X-ray studies. Our
analysis provides further evidence of the ongoing dynamical evolution in the
ShaSS region.
