Joint JWST-DECam Lensing Reveals That the Bullet Cluster Is a Minor Merger
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| Format: | Preprint |
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2025
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| _version_ | 1866917121037959168 |
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| author | Cho, Boseong Young Jee, M. James Joo, Hyungjin Cha, Sangjun HyeongHan, Kim |
| author_facet | Cho, Boseong Young Jee, M. James Joo, Hyungjin Cha, Sangjun HyeongHan, Kim |
| contents | 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 $\sim$2:1 to $\gtrsim$10:1 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 $M_{200c} = 15.11^{+2.48}_{-2.10} \times 10^{14}M_{\odot}$ for the main cluster and $1.49^{+0.32}_{-0.25} \times 10^{14}M_{\odot}$ 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_03150 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Joint JWST-DECam Lensing Reveals That the Bullet Cluster Is a Minor Merger Cho, Boseong Young Jee, M. James Joo, Hyungjin Cha, Sangjun HyeongHan, Kim Astrophysics of Galaxies 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 $\sim$2:1 to $\gtrsim$10:1 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 $M_{200c} = 15.11^{+2.48}_{-2.10} \times 10^{14}M_{\odot}$ for the main cluster and $1.49^{+0.32}_{-0.25} \times 10^{14}M_{\odot}$ 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. |
| title | Joint JWST-DECam Lensing Reveals That the Bullet Cluster Is a Minor Merger |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2512.03150 |