Chandra and XMM-Newton Observations of the Bimodal Planck SZ-detected
  Cluster PLCKG345.40-39.34 (A3716) with High and Low Entropy Subcluster Cores
  We present results from Chandra, XMM-Newton, and ROSAT observations of the
Planck SZ-detected cluster A3716 (PLCKG345.40-39.34 - G345). We show that G345
is, in fact, two subclusters separated on the sky by 400 kpc. We measure the
subclusters' gas temperatures (~ 2-3 keV), total (~ 1-2 x 10^14 solar masses)
and gas (~ 1-2 x 10^13 solar masses) masses, gas mass fraction within r500,
entropy profiles, and X-ray luminosities (~ 10^43 erg/s). Using the gas density
and temperature profiles for both subclusters, we show that there is good (0.8
sigma) agreement between the expected Sunyaev-Zel'dovich signal predicted from
the X-ray data and that measured from the Planck mission, and better agreement
within 0.6 sigma when we re-computed the Planck value assuming a two component
cluster model, with relative amplitudes fixed based on the X-ray data.
Dynamical analysis shows that the two galaxy subclusters are very likely (> 97%
probability) gravitationally bound, and in the most likely scenario, the
subclusters will undergo core passage in 500 +- 200 Myr. The northern
subcluster is centrally peaked and has a low entropy core, while the southern
subcluster has a high central entropy. The high central entropy in the southern
subcluster can be explained either by the mergers of several groups, as
suggested by the presence of five giant ellipticals or by AGN energy injection,
as suggested by the presence of a strong radio source in one of its massive
elliptical galaxies, or by a combination of both processes.
