Oral Presentation

JWST Lensing Analysis of Merging Galaxy Clusters: The Bullet Cluster and Abell 2744

Author(s): Sangjun Cha (Yonsei University), Kim HyeongHan (Yonsei University), Boseong Cho (Yonsei University), Zachary Scofield (Yonsei University), Hyungjin Joo (Yonsei University), Wonki Lee (Yonsei University), Kyle Finner (Caltech/IPAC), James Jee (Yonsei University, UC Davis)

Presenter: Sangjun Cha (Yonsei University)

Merging galaxy clusters can serve as cosmic dark matter colliders, enabling the study of energy scales that are impossible to reproduce on Earth. To understand their dynamics and formation history, precise mass measurements are essential. By leveraging deep JWST observations, we combine strong lensing (SL) and weak lensing (WL) data to reconstruct mass maps from the cluster cores to their outskirts. The unprecedented depth and resolution of JWST imaging allow us to achieve around four times higher source density for WL analysis compared to HST, and to identify a few hundred multiple images for SL analysis. We present two case studies: Abell 2744 and the Bullet Cluster. In Abell 2744, our mass map reveals mass bridges connecting the main mass clumps. Correlating with radio relic positions may indicate the directions of merger axes. For the Bullet Cluster, we detect a strong spatial correlation between intracluster light (ICL) and the mass distributions from lensing analysis. This alignment suggests that ICL would be a reliable tracer of dark matter, even in highly dynamic systems such as cluster mergers. These multi-wavelength analyses combining SL and WL allow us to probe the complex mass structures, dynamics, and formation histories of merging galaxy clusters in the JWST era.