MACS J0553.4−3342: a young merging galaxy cluster caught through the eyes of Chandra and HST

Abstract

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.