{
  "abstract": "We present JWST NIRSpec IFU spectroscopic measurements of one of the faintest (M$_{UV}>-13.6$) known ionizing sources at $z=5.66$, dubbed Small And Lensed Source Arc, SALSA. This source is highly magnified ($μ>100$) by the lensing galaxy cluster Abell 2744, providing a unique opportunity to investigate the physical properties of faint sources in the Epoch of Reionization. We characterize SALSA's nebular emission using rest-frame UV and optical emission lines and investigate the relationship between its ionizing efficiency, nebular excitation, and chemical enrichment. We robustly detect H$α$ emission and use it to predict the H$β$ flux assuming negligible dust attenuation. We also measure the [OIII]$λ$5007 emission and estimate oxygen abundance resulting in a high R3 index $2.82_{-0.25}^{+0.34}$ and relatively low metallicity $\\mathrm{12+log(O/H)}= 7.43\\pm0.09$. SALSA presents a high ionizing production efficiency log$(ξ_{ion})=25.49_{-0.08}^{+0.09}$ Hz erg $^{-1}$, consistent with theoretical models from very massive stars and constant star formation rate, and a high Ly$α$ escape fraction $f_{\\mathrm{esc}}^{\\mathrm{Ly}α}=0.39\\pm0.14$. These properties place SALSA among the most extreme star-forming sources known at this epoch.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.09281",
  "author_total": 8,
  "authors": [
    {
      "name": "Sofía Rojas-Ruiz"
    },
    {
      "name": "Matteo Messa"
    },
    {
      "name": "Eros Vanzella"
    },
    {
      "name": "Tommaso Treu"
    },
    {
      "name": "Pietro Bergamini"
    },
    {
      "name": "Giorgia Di Rosa"
    },
    {
      "name": "Marco Lombardi"
    },
    {
      "name": "Piero Rosati"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/53x85ywdxn4px.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09281",
  "fulltext_url": null,
  "id": "53x85ywdxn4px",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.09281",
  "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": "W7212139996",
  "pdf_url": "https://arxiv.org/pdf/2609.09281",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/53x85ywdxn4px.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:12Z",
      "native_id": "2609.09281",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09281"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Chasing Cosmic Reionization: An Extremely Faint Highly Magnified Source at $z=5.66$ with high $ξ_{\\rm ion}$",
  "title_text": "Chasing Cosmic Reionization: An Extremely Faint Highly Magnified Source at z=5.66 with high ξ_ion",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:12Z",
  "url": "https://research.draconitic.com/paper/53x85ywdxn4px",
  "venue": "arXiv",
  "versions": []
}