{
  "abstract": "[abridged] Star formation is a key process driving galaxy evolution, but understanding how it proceeds within the interstellar medium (ISM) requires resolving cold molecular gas and dust on sub-kpc scales. At z~2-3, near the peak of cosmic star formation, such resolution can generally only be achieved through strong gravitational lensing. We present an ALMA study of SMMJ0658, a 20x-magnified main-sequence star-forming galaxy at z=2.7768 +/- 0.0002, lensed by the Bullet Cluster (z=0.296) into three images. We use 0.2\" and 0.6\" ALMA Band-3 observations to test the Kennicutt-Schmidt (KS) relation at sub-kpc scales at cosmic noon. Using a JWST-based strong-lensing model of the Bullet Cluster, we reconstruct source-plane CO(3-2) and rest-frame 803um dust-continuum maps down to ~200pc scales. We derive spatially resolved molecular gas and star formation rate surface densities, depletion times, and the scale dependence of the CO-to-dust flux ratio over 200pc-3.2kpc apertures. The 0.2\" ALMA data reveal massive, dense star-forming clumps, with Sigma_mol ~1.3-2.3 x 10^3 M_sun pc^-2, Sigma_SFR ~0.5-2.3 M_sun yr^-1 kpc^-2, and tau_dep ~0.82-2.56 Gyr. CO-dust spatial decorrelation produces a strong scale dependence in tau_dep. We find a KS-relation breakdown scale of 0.8 +/- 0.1 kpc, consistent with individual regions tracing distinct stages of the star-formation cycle. The ALMA and JWST data also reveal evidence for a lensed galaxy pair at z~2.78, although whether SMMJ0658 is undergoing an early-stage interaction remains uncertain. Our results show that the apparent universality of the KS relation breaks down once individual star-forming regions are spatially resolved, in line with observations from the local universe to z~1. We extend this picture to z~2.78, providing new insight into the resolved properties of the clumpy cold ISM and the star-formation cycle at cosmic noon.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.40233",
  "author_total": 12,
  "authors": [
    {
      "name": "C. Cornil-Baïotto"
    },
    {
      "name": "J. Molina"
    },
    {
      "name": "G. Mahler"
    },
    {
      "name": "G. Rihtaršič"
    },
    {
      "name": "M. Boquien"
    },
    {
      "name": "M. Bradač"
    },
    {
      "name": "E. Ibar"
    },
    {
      "name": "A. H. Gonzalez"
    },
    {
      "name": "T. Verdugo"
    },
    {
      "name": "O. López-Cruz"
    },
    {
      "name": "J. Magaña"
    },
    {
      "name": "V. Motta"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0f5dwzkn42yez.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.40233",
  "fulltext_url": null,
  "id": "0f5dwzkn42yez",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.40233",
  "language": null,
  "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.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7215069159",
  "pdf_url": "https://arxiv.org/pdf/2609.40233",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0f5dwzkn42yez.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:49Z",
      "native_id": "2609.40233",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.40233"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Sub-kiloparsec Test of the Kennicutt-Schmidt Relation in a Strongly Lensed Dusty Star-Forming Galaxy at z~2.78",
  "title_text": "Sub-kiloparsec Test of the Kennicutt-Schmidt Relation in a Strongly Lensed Dusty Star-Forming Galaxy at z~2.78",
  "type": "preprint",
  "updated_at": "2026-11-09T00:20:15Z",
  "url": "https://research.draconitic.com/paper/0f5dwzkn42yez",
  "venue": "arXiv",
  "versions": []
}