Weak-Lensing Detection of Intracluster Filaments in the Coma Cluster

TL;DR

This study presents the first weak-lensing detection of dark matter in intracluster filaments connected to the Coma cluster, confirming their existence and alignment with large-scale cosmic structures.

Contribution

It provides the first observational weak-lensing evidence of dark matter in intracluster filaments, supporting the cosmic web model.

Findings

Detection of intracluster filaments with high significance

Filaments align with known large-scale cosmic structures

Dark matter component confirmed in filaments

Abstract

Our concordance cosmological model predicts that galaxy clusters grow at the intersection of filaments structuring the cosmic web stretching tens of Mega parsecs. Although this hypothesis has been supported by the baryonic components, no observational study has detected the dark matter component of the intracluster filaments (ICFs), the terminal segment of the large-scale cosmic filaments at their conjunction with individual clusters. We report weak-lensing detection of ICFs in the Coma cluster field from the ~12 sq. deg Hyper Suprime-Cam imaging data. The detection is based on two methods: matched-filter technique and shear-peak statistic. The matched-filter technique (shear-peak statistic) yields detection significances of 6.6- (3.1) $\sigma$ and 3.6- (2.8) $\sigma$ for the northern and western ICFs at 110$^{\circ}$ and 340$^{\circ}$, respectively. Both ICFs are highly correlated with the overdensities in the WL mass reconstruction and are well-aligned with the known large-scale ($>10$ Mpc) cosmic filaments comprising the Coma supercluster.