Dynamical history of a binary cluster: Abell 3653
  We study the dynamical structure of a bimodal galaxy cluster Abell 3653 at
z=0.1089 by using combined optical and X-ray data. Observations include
archival data from Anglo-Australian Telescope and X-ray observatories of
XMM-Newton and Chandra. We draw a global picture for A3653 using galaxy
density, X-ray luminosity and temperature maps. Galaxy distribution has a
regular morphological shape at the 3 Mpc size. Galaxy density map shows an
elongation EW direction, which perfectly aligns with the extended diffuse X-ray
emission. We detect two dominant grouping around two brightest cluster galaxies
(BCGs). The BCG1 (z=0.1099) can be associated with the main cluster A3653E, and
a foreground subcluster A3563W concentrated at the BCG2 (z=0.1075). Both X-ray
peaks are dislocated from BCGs by ($\sim$35 kpc), which suggest an ongoing
merger process. We measure the subclusters' gas temperatures 4.67 and 3.66 keV,
respectively. Two-body dynamical analysis shows that A3653E & A3653W are very
likely (93.5% probability) gravitationally bound. The highly favoured scenario
suggests that two subclusters with the mass ratio of 1.4 are colliding close to
the plane of sky ($\alpha$=17$^\circ$.61) with 2400 km $s^{-1}$, and will
undergo core passage in 380 Myr. Temperature map also significantly shows a
shock-heated gas (6.16 keV) in between the subclusters, which confirms the
supersonic infalling scenario.
