FRONTIER FIELDS: SUBARU WEAK-LENSING ANALYSIS OF THE MERGING GALAXY CLUSTER A2744*

Abstract

ABSTRACT We present a weak-lensing analysis of the merging 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 c = ( 2.06 ± 0.42 ) × 10 15 M ☉ . ?> The most massive clump is the southern component with M 200 c = ( 7.7 ± 3.4 ) × 10 14 M ⊙ , ?> followed by the western substructure ( M 200 c = ( 4.5 ± 2.0 ) × 10 14 M ⊙ ?> ) and two smaller substructures to the northeast ( M 200 c = ( 2.8 ± 1.6 ) × 10 14 M ⊙ ?> ) and northwest ( M 200 c = ( 1.9 ± 1.2 ) × 10 14 M ⊙ ?> ). 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.