Multi-wavelength landscape of the young galaxy cluster RXJ1257.2+4738 at
  z=0.866. II. Morphological properties
  The study of the evolution of the morphological distribution of galaxies in
different environments can provide important information about the effects of
the environment and the physical mechanisms responsible for the morphological
transformations. As part of a complete analysis of the young cluster
RXJ1257+4738 at z$\sim$0.9, we studied in this work the morphological
properties of its galaxies. We used non-parametric methods of morphological
classification, as implemented in the galSVM code. The classification with the
applied method was possible even using ground-based observations: r'-band
imaging from OSIRIS/GTC. We defined very conservative probability limits,
taking into account the probability errors, in order to obtain a trustworthy
classification. In this way we were able to classify about the 30% of all
cluster members, and to separate between LT and ET galaxies. Additionally, when
analysing the colour-magnitude diagram, we observed a significant population of
blue ET galaxies between the classified ones. We discussed possible
explanations for the finding of this population. Moreover, we studied different
physical properties of LT, ET, and blue ET galaxies. They turn out to be
comparable, with the exception of the stellar mass that shows that the red ET
population is more massive. We also analysed the morphology-density and
morphology-radius relations, observing that, only when considering the
morphological separation between ET and LT galaxies, a mild classical behaviour
is obtained. RXJ1257+4738 is a young galaxy cluster, showing a clumpy structure
and being still in the process of formation, which could explain the lack of
some of the standard morphological relations. This makes this cluster a very
attractive case for obtaining the higher resolution data and for studying in
more details the morphological properties of the entire cluster and relation
with the environment.
