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_$200\mathrm{c}$ = (2.06\pm0.42)\times10^{15},M_\odot$. The most massive clump is the southern component with $M_{200\mathrm{c}}=(7.7\pm 3.4)\times {10}^{14}{M}_{\odot }$, followed by the western substructure ($M_$200\mathrm{c}$ = (4.5\pm2.0)\times10^{14},M_\odot$) and two smaller substructures to the northeast ($M_{200\mathrm{c}}=(2.8\pm 1.6)\times {10}^{14}{M}_{\odot }$) and northwest ($M_{200\mathrm{c}}=(1.9\pm 1.2)\times {10}^{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 ($87_{-28}^{+34}$ arcsec, 90% CL) and the galaxies ($72_{-53}^{+34}$ 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.