MACS J0553.4-3342: A young merging galaxy cluster caught through the
  eyes of Chandra and HST
  We present a detailed analysis of a young merging galaxy cluster
\mac~(z=0.43), from {\it Chandra} X-ray and {\it Hubble Space Telescope}
archival data. X-ray observations confirm that the X-ray emitting intra-cluster
medium (ICM) in this system is among the hottest (average $T=12.1 \pm 0.6$ keV)
and most luminous known. Comparison of X-ray and optical images confirm that
this system hosts two merging subclusters SC1 and SC2, separated by a projected
distance of about 650\,kpc. The subcluster SC2 is newly identified in this
work, while another subcluster (SC0), previously thought to be part of this
merging system, is shown to be possibly a foreground object. Apart from two
subclusters, we find a tail-like structure in the X-ray image, extending to a
projected distance of $\sim$1\,Mpc, along the north-east direction of the
eastern subcluster (SC1). From a surface brightness analysis, we detect two
sharp surface brightness edges at $\sim$40$\arcsec$ ($\sim$320\,kpc) and
$\sim$80$\arcsec$ ($\sim$640\,kpc) to the east of SC1. The inner edge appears
to be associated with a merger-driven cold front, while the outer one is likely
to be due to a shock front, the presence of which, ahead of the cold front,
makes this dynamically disturbed cluster interesting. Nearly all the early-type
galaxies belonging to the two subclusters, including their BCGs, are part of a
well-defined red sequence.
