MC2: A Deeper Look at ZwCl 2341.1+0000 with Bayesian Galaxy Clustering and Weak Lensing Analyses

Abstract

Abstract ZwCl 2341.1+0000, a merging galaxy cluster with disturbed X-ray morphology and widely separated (∼3 Mpc) double radio relics, was thought to be an extremely massive ( 10 – 30 × 10 14 M ⊙ ) and complex system, with little known about its merger history. We present JVLA 2–4 GHz observations of the cluster, along with new spectroscopy from our Keck/DEIMOS survey, and apply Gaussian Mixture Modeling to the three-dimensional distribution of 227 confirmed cluster galaxies. After adopting the Bayesian Information Criterion to avoid overfitting, which we discover can bias high the total dynamical mass estimates, we find that a three-substructure model with a total dynamical mass estimate of 9.39 ± 0.81 × 10 14 M ⊙ is favored. We also present deep Subaru imaging and perform the first weak lensing analysis on this system, obtaining a weak lensing mass estimate of 5.57 ± 2.47 × 10 14 M ⊙ . This is a more robust estimate because it does not depend on the dynamical state of the system, which is disturbed due to the merger. Our results indicate that ZwCl 2341.1+0000 is a multiple merger system comprised of at least three substructures, with the main merger that produced the radio relics occurring near the plane of the sky, and a younger merger in the north occurring closer to the line of sight. Dynamical modeling of the main merger reproduces observed quantities (relic positions and polarizations, subcluster separation and radial velocity difference), if the merger axis angle of ∼ 10 − 6 + 34 degrees and the collision speed at pericenter is ∼ 1900 − 200 + 300 km s−1.