The dynamical state of Abell 2399: a bullet-like cluster
  While there are many ways to identify substructures in galaxy clusters using
different wavelengths, each technique has its own caveat. In this paper, we
conduct a detailed substructure search and dynamical state characterisation of
Abell 2399, a galaxy cluster in the local Universe ($z \sim 0.0579$), by
performing a multi-wavelength analysis and testing the results through
hydro-dynamical simulations. In particular, we apply a Gaussian Mixture Model
to the spectroscopic data from SDSS, WINGS, and Omega WINGS Surveys to identify
substructures. We further use public \textit{XMM-Newton} data to investigate
the intracluster medium (ICM) thermal properties, creating temperature,
metallicity, entropy, and pressure maps. Finally, we run hydro-dynamical
simulations to constrain the merger stage of this system. The ICM is very
asymmetrical and has regions of temperature and pressure enhancement that
evidence a recent merging process. The optical substructure analysis retrieves
the two main X-ray concentrations. The temperature, entropy, and pressure are
smaller in the secondary clump than in the main clump. On the other hand, its
metallicity is considerably higher. This result can be explained by the
scenario found by the hydro-dynamical simulations where the secondary clump
passed very near to the centre of the main cluster possibly causing the
galaxies of that region to release more metals through the increase of
ram-pressure stripping.16
