{
  "abstract": "We present a new strong-lensing and X-ray mass model of the merging galaxy cluster SPT-CLJ1150-2805 ($z=0.383$), combining JWST NIRCam, HST, Chandra, and VLT/MUSE data to robustly decompose its collisionless and collisional components. Exploiting JWST, we expand the multiple-image catalogue with 66 new images (30 comprising 6 new systems). Our baseline model uses 118 spectroscopically confirmed images from 20 systems, achieving an image-plane root-mean-square offset of $0.56''$. An expanded model incorporating 31 additional photometric images from 8 additional systems yields a near-identical mass distribution, confirming excellent model stability. We resolve a complex multi-axis post-merger system requiring five cluster-scale dark matter haloes, including a bimodal core with distinct haloes coincident with each brightest cluster galaxy. The remaining mass components are independently supported by kinematics of 291 cluster members ($σ_v=1960^{+84}_{-92}$ km s$^{-1}$), which reveal two new galaxy substructures - the northernmost of which we tentatively identify as the baryonic counterpart to our fifth dark matter halo. The cluster is an extraordinarily efficient lens, possessing an effective Einstein radius $θ_E=42.41^{+0.05}_{-0.04}{''}$ and an enclosed mass $M(<θ_E)=3.35^{+0.04}_{-0.03}\\times10^{14}M_\\odot$ for a source at $z_s=2$. For a high-redshift source at $z_s=9$, it produces a magnification cross-section of $A(>10)\\simeq0.15$ arcmin$^2$ and $A(>30)\\simeq0.020$ arcmin$^2$. This global lensing power surpasses all Hubble Frontier Fields clusters. In a regime where systematic uncertainties between mass models dominate high-redshift magnification errors, the stability of our reconstruction sets this lens apart. This combination of extreme lensing power and a robust mass model establishes SPT-CLJ1150-2805 as a premier cosmic telescope for high-redshift studies.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.31944",
  "author_total": 19,
  "authors": [
    {
      "name": "James R Betts"
    },
    {
      "name": "Benjamin Beauchesne"
    },
    {
      "name": "Mathilde Jauzac"
    },
    {
      "name": "David Lagattuta"
    },
    {
      "name": "Guillaume Mahler"
    },
    {
      "name": "Jean-Paul Kneib"
    },
    {
      "name": "Gavin Leroy"
    },
    {
      "name": "Marceau Limousin"
    },
    {
      "name": "Priyamvada Natarajan"
    },
    {
      "name": "Sameeksha Saini"
    },
    {
      "name": "Keren Sharon"
    },
    {
      "name": "Stephane V Werner"
    },
    {
      "name": "Catherine Cerny"
    },
    {
      "name": "Isaque Dutra"
    },
    {
      "name": "Dominique Eckert"
    },
    {
      "name": "Alaina Einsig"
    },
    {
      "name": "Michael D Gladders"
    },
    {
      "name": "Gourav Khullarm"
    },
    {
      "name": "Manon Regamey"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/d739avk94rnz6.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.31944",
  "fulltext_url": null,
  "id": "d739avk94rnz6",
  "issns": [],
  "landing_url": "https://hal.science/hal-05830217v1",
  "language": "en",
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7214752959",
  "pdf_url": "https://arxiv.org/pdf/2609.31944",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/d739avk94rnz6.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:00Z",
      "native_id": "hal-05830217",
      "source": "hal",
      "url": "https://hal.science/hal-05830217v1"
    },
    {
      "first_seen": "2026-10-30T12:25:12Z",
      "native_id": "2609.31944",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.31944"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "SLICE: Unveiling the Multi-Component Merging Core of SPT-CLJ1150-2805 Through Strong-Lensing Mass Modelling",
  "title_text": "SLICE: Unveiling the Multi-Component Merging Core of SPT-CLJ1150-2805 Through Strong-Lensing Mass Modelling",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:12Z",
  "url": "https://research.draconitic.com/paper/d739avk94rnz6",
  "venue": "HAL",
  "versions": []
}