2025/12/02 by Boseong Young Cho, M. James Jee, Cho, Boseong Young +7 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.2512.03150
21 pages, 12 figures, 3 tables, accepted for publication in ApJ
arxiv created 2026/07/28 · arxiv updated 2026/07/30
We present the first robust virial masses of the Bullet Cluster's three individual components from a joint weak+strong lensing analysis combining JWST/NIRCam and DECam observations. Despite its status as the benchmark system for dark matter and merger studies, inferred mass ratios for the Bullet Cluster have spanned a wide range from ∼2:1 to \gtrsim10:1 over more than two decades. We revisit this tension through three key advances: (1) JWST's exceptional data quality enables us to resolve three distinct halos, (2) DECam's wide-field coverage beyond its virial radius eliminates the need for extrapolation, and (3) high-fidelity strong-lensing priors mitigate weak-lensing model bias. We obtain M200c = 15.11+2.48-2.10 × 1014M\odot for the main cluster and 1.49+0.32-0.25 × 1014M\odot for the subcluster, yielding a mass ratio of 10.14+3.22-2.47, definitively classifying the Bullet Cluster as a minor merger. This result reconciles the long-standing tension in the mass ratio and provides updated initial parameters for future modeling of this iconic system.