Revealing A Head-on Major Merger in the Nearby NGC 6338 Group with
  Chandra and VLA observations
  By analyzing the Chandra archival data of the nearby NGC 6338 galaxy group,
we identify two X-ray bright clumps (N-clump and S-clump) within the central
100 kpc, and detect an arc-like X-ray brightness discontinuity at the south
boundary of the N-clump, which is defined as a cold front with a gas flow Mach
number of M<0.8. Furthermore, at the north-east boundary of the S-clump
(dominated by galaxy NGC 6338) another X-ray edge is detected that corresponds
to a weaker cold front. Therefore, the two clumps are approaching each other
approximately from opposite directions, and the group is undergoing a head-on
collision that is in a stage of pre-core passage. This merger scenario is also
supported by the study of the line-of-sight velocity distribution of the group
member galaxies. The merger mass ratio is about 1:1.8 as estimated from the
central gas temperature of the two clumps, which suggests the merger is most
likely to be a major merger. We also analyze the VLA 1.4 and 4.9 GHz radio
data, but we do not detect any extended radio emission that is associated with
the merger.
