Strong lensing in RX J1347.5-1145 revisited
  We present a revised strong lensing mass reconstruction of the galaxy cluster
RX J1347.5-1145. The X-ray luminous cluster at redshift z=0.451 has already
been studied intensively in the past. Based on information of two such previous
(strong-)lensing studies by Halkola et al. (2008) and Bradac et al. (2008), as
well as by incorporating newly available data from the Cluster Lensing And
Supernovae survey with Hubble (CLASH, Postman et al. 2012), we identified four
systems of multiply lensed images (anew) in the redshift range 1.75 <= z <=
4.19. One multiple image system consists of in total eight multiply lensed
images of the same source. The analysis based on a parametric mass model
derived with the software glafic (Oguri 2010) suggests that the high image
multiplicity is due to the source (z_phot = 4.19) being located on a so-called
"swallowtail" caustic. In addition to the parametric mass model, we also
employed a non-parametric approach using the software PixeLens (Saha and
Williams 1997, 2004) in order to reconstruct the projected mass of the cluster
using the same strong lensing data input.
  Both reconstructed mass models agree in revealing several mass components and
a highly elliptic shape of the mass distribution. Furthermore, the projected
mass inside, for example, a radius R ~35 arcsec ~200 kpc of the cluster for a
source at redshift z=1.75 obtained with PixeLens exceeds the glafic estimate
within the same radius by about 13 per cent. The difference could be related to
the fundamental degeneracy involved when constraining dark matter substructures
with gravitationally lensed arcs.
