Constraining the cross-section of dark matter with giant radial arcs in
  galaxy clusters
  We compare the statistics and morphology of giant arcs in galaxy clusters
using N-body and non-radiative SPH simulations within the standard cold dark
matter model and simulations where dark matter has a non-negligible probability
of interaction (parametrized by its cross-section), i.e self-interacting dark
matter (SIDM). We use a ray-tracing technique to produce a statistically large
number of arcs around six simulated galaxy clusters at different redshifts.
Since dark matter is more likely to interact in colliding clusters than in
relaxed clusters, and this probability of interaction is largest in denser
regions, we focus our analysis on radial arcs (which trace the lensing
potential in the central region better than tangential arcs) in galaxy clusters
which underwent (or are undergoing) a major merger. We find that
self-interacting dark matter produces fewer radial arcs than standard cold dark
matter but they are on average more magnified. We also appreciate differences
in the arc morphology that could be used to statistically favor one model
versus the other.
