The dynamical state of RXCJ1230.7+3439: a multi-substructured merging
  galaxy cluster
  We analyse the kinematical and dynamical state of the galaxy cluster
RXCJ1230.7+3439, at z=0.332, using 93 new spectroscopic redshifts of galaxies
acquired at the 3.6m TNG telescope and from SDSS DR16 public data. We find that
RXCJ1230 appears as a clearly isolated peak in the redshift space, with a
global line-of-sight velocity dispersion of $1004_{-122}^{+147}$ km s$^{-1}$,
and showing a very complex structure with the presence of three subclusters.
Our analyses confirm that the three substructures detected are in a pre-merger
phase, where the main interaction takes place with the south-west subclump. We
compute a velocity dispersion of $\sigma_\textrm{v} \sim 1000$ and
$\sigma_\textrm{v} \sim 800$ km s$^{-1}$ for the main cluster and the
south-west substructure, respectively. The central main body and south-west
substructure differ by $\sim 870$ km s$^{-1}$ in the LOS velocity. From these
data, we estimate a dynamical mass of $M_{200}= 9.0 \pm 1.5 \times 10^{14}$
M$_{\odot}$ and $4.4 \pm 3.3 \times 10^{14}$ M$_{\odot}$ for the RXCJ1230 main
body and south-west clump, respectively, which reveals that the cluster will
suffer a merging characterized by a 2:1 mass ratio impact. We solve a two-body
problem for this interaction and find that the most likely solution suggests
that the merging axis lies almost contained in the plane of the sky and the
subcluster will fully interact in $\sim0.3$ Gyr. The comparison between the
dynamical masses and those derived from X-ray data reveals a good agreement
within errors (differences $\sim 15$\%), which suggests that the innermost
regions ($<r_{500}$) of the galaxy clumps are almost in hydrostatical
equilibrium. To summarize, RXCJ1230 is a young but also massive cluster in a
pre-merging phase accreeting other galaxy systems from its environment.
