Wide-field Weak-lensing Analysis of the Coma Cluster with Hyper Suprime-Cam Data

The Coma Cluster is one of the most extensively studied rich galaxy clusters thanks to its proximity (z=0.023; D~100 Mpc). In-depth investigations of the cluster properties have provided tremendous contributions to our understanding of similarly massive clusters in the distant universe. However, the mass of the Coma Cluster is still highly uncertain. In this study, we perform a wide-field (~4 deg × 4 deg) weak-lensing analysis of the Coma Cluster using Hyper Suprime-Cam observations and present the first weak-lensing mass estimate from the full coverage of its virial radius without any extrapolation. After careful shear calibration, we find that the total mass of the Coma Cluster is significantly larger than previous weak-lensing estimates. We also discuss the peculiar central mass substructures that are characterized by three distinct mass peaks. The two mass clumps coincide with the two brightest galaxies NGC 4874 and NGC 4889 while the other one shows no apparent association with bright galaxies despite its high (~8 σ) detection significance.