CFHT MegaCam Two Deep Fields Imaging Survey (2DFIS) II: Decoding the Lensing Profile of a "Rotating" Cluster with Deep CFHT Imaging

TL;DR

This study combines multi-wavelength data to analyze a galaxy cluster, revealing that apparent rotation signals are due to projection effects of a filament, not actual rotation, and clarifies the mass distribution discrepancies between optical and X-ray observations.

Contribution

It demonstrates that optical bimodality and rotation signals can be caused by projection effects, emphasizing the importance of multi-wavelength analysis in cluster dynamics.

Findings

Weak lensing reveals dominant mass concentration in one substructure.

Optical bimodality results from filament projection, not true rotation.

Misclassification of galaxies leads to overestimated halo mass.

Abstract

We present a multi-wavelength analysis of the galaxy cluster RXCJ0110.0+1358 ($z=0.058$), a rotating cluster candidate, combining deep CFHT imaging, SDSS photometry, spectroscopic redshifts, and XMM-Newton X-ray observations. We find a notable discrepancy between the optical and X-ray views: while optical data reveal a pronounced bimodal galaxy distribution with significant kinematic substructure signatures, the X-ray emission exhibits a single, smoothly extended component centered on the BCG. Our weak lensing analysis resolves this discrepancy by revealing that the mass is predominantly concentrated in the southeast ($\log M_{200}/M_\odot = 14.04_{-0.40}^{+0.24}$), while the northwestern substructure has a negligible mass ($\sim 10^{13} M_\odot$). This immense mass disparity rules out the dynamical possibility of a rotating system. We demonstrate that the apparent optical bimodality arises from the projection of a filament, which led optical group-finding algorithms to misclassify these galaxies as cluster members. This contamination creates a spurious substructure that mimics a rotation signal and leads to an overestimation of the luminosity-based halo mass, resolving the observed inconsistencies.