Weak-lensing Analysis of Intracluster Filaments in Abell 2744: Matched-filter Scans and Stepwise 2D Tracing
astro-ph.GA, astro-ph.CO
Submitted: 2026-04-08
Updated: 2026-09-21
Comments: 22 pages, 13 figures; published in ApJ
Journal ref: 2026 ApJ 1009 93
License: http://creativecommons.org/licenses/by/4.0/
The gist: We present a weak-lensing (WL) analysis of filamentary structures in the merging galaxy cluster Abell 2744 using wide-field Magellan/MegaCam imaging data.
Terminology
Abstract
We present a weak-lensing (WL) analysis of filamentary structures in the merging galaxy cluster Abell 2744 using wide-field Magellan/MegaCam imaging data. We employ two complementary techniques: standard matched-filter scans to identify global orientations, and a new stepwise 2D tracing method to reconstruct locally varying filament orientations. The matched-filter analysis detects coherent filamentary features in the northwest and east directions across both inner (1.0-2.2 Mpc) and outer (2.2-3.4 Mpc) annuli. However, while the northwest filament yields consistent constraints across both regions, parameter inference for the eastern structure remains unstable and radially inconsistent when using the fiducial reference point. Additional matched-filter scans centered on the three lensing mass peaks show that the inferred directions depend on the adopted reference point. We demonstrate that re-characterizing the eastern structure using the locally preferred stepwise-traced direction significantly resolves these tensions, improving fit quality and bringing inner and outer constraints into agreement. These results show that stepwise 2D tracing complements global matched-filter scans by tracing locally coherent directions without requiring the full structure to pass through a single predefined point. Furthermore, the detected filaments align well with diffuse X-ray structures and previously identified merger axes, supporting their physical connection to the cluster's mass assembly.
Sources
- The final WaZP galaxy cluster catalog of the Dark Energy Survey and comparison with SZE data
- Non-linear Least Squares Fitting in IDL with MPFIT
- Weak-Lensing Detection of Intercluster Filaments in Three Nearby Cluster Systems
- Reproducing Abell 2744 with the HyperMillennium Simulation
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