Weak-Lensing Detection of Intercluster Filaments in Three Nearby Cluster Systems
Authors
Rahul Shinde
Ian Dell'Antonio
Abstract
Direct detection of intercluster filaments is challenging due to their low surface density, resulting in a weak deflection field. We present weak-lensing detections of intercluster filaments using wide-field Dark Energy Camera (DECam) observations from the Local Volume Complete Cluster Survey (LoVoCCS). A matched-filter method was applied to identify filamentary structures in three nearby ($z < 0.1$) systems centered on Abell 401, Abell 2029, and Abell 3558. We discover two prominent filaments ($\geq 4σ$) in each system, with the strongest detections ($6.4σ- 7.3σ$) around Abell 401 and Abell 2029. In particular, we report the first robust weak-lensing detections $(>5 σ)$ of the intercluster bridges connecting the cluster pairs Abell 401/399, Abell 2029/2033, Abell 2029/SIG, and Abell 3558/3556. Adopting a filament convergence model motivated by numerical simulations, we infer the maximum convergence ($κ_0$) and characteristic width ($h_{\mathrm{c}}$) for all six filaments, yielding $κ_0 \sim 0.015 - 0.053$ and $h_{\mathrm{c}} \sim 0.11 - 0.45 \ \mathrm{Mpc}$. The performance of the matched-filter technique is validated using mock shear catalogs and further tested on a null field around Abell 2351. We also explore the potential of using the B-mode lensing signal of filaments to suppress cluster-induced shear contamination. These results demonstrate the feasibility of directly mapping dark matter filaments with current and future wide-field weak-lensing datasets.
