Frontier Fields: Subaru Weak-Lensing Analysis of the Merging Galaxy
  Cluster A2744
  We present a weak-lensing analysis of the merging {\em Frontier Fields} (FF)
cluster Abell~2744 using new Subaru/Suprime-Cam imaging. The wide-field lensing
mass distribution reveals this cluster is comprised of four distinct
substructures. Simultaneously modeling the two-dimensional reduced shear field
using a combination of a Navarro--Frenk--White (NFW) model for the main core
and truncated NFW models for the subhalos, we determine their masses and
locations. The total mass of the system is constrained as $M_\mathrm{200c} =
(2.06\pm0.42)\times10^{15}\,M_\odot$. The most massive clump is the southern
component with $M_\mathrm{200c} = (7.7\pm3.4)\times10^{14}\,M_\odot$, followed
by the western substructure ($M_\mathrm{200c} =
(4.5\pm2.0)\times10^{14}\,M_\odot$) and two smaller substructures to the
northeast ($M_\mathrm{200c} = (2.8\pm1.6)\times10^{14}\,M_\odot$) and northwest
($M_\mathrm{200c} = (1.9\pm1.2)\times10^{14}\,M_\odot$). The presence of the
four substructures supports the picture of multiple mergers. Using a composite
of hydrodynamical binary simulations we explain this complicated system without
the need for a "slingshot" effect to produce the northwest X-ray interloper, as
previously proposed. The locations of the substructures appear to be offset
from both the gas ($87^{+34}_{-28}$ arcsec, 90\% CL) and the galaxies
($72^{+34}_{-53}$ arcsec, 90\% CL) in the case of the northwestern and western
subhalos. To confirm or refute these findings, high resolution space-based
observations extending beyond the current FF limited coverage to the west and
northwestern area are essential.
