{
  "abstract": "Context. Protoclusters at reionization are thought to host a significant fraction of the cosmic star formation rate density, making them crucial for the timing and topology of reionization. The gas-phase metallicity, a key tracer of galaxy evolutionary stage, can now be measured directly in the early Universe with JWST. Aims. We measure the gas-phase metallicity of Lyman-$α$ emitters (LAEs) in the LAGER-z7OD1 protocluster at $z\\approx6.93$ via the direct ($T_e$-based) method using the [O III]$λ$4363 auroral line, and combine it with stellar masses to constrain the mass-metallicity relation (MZR) in dense environments. Methods. We use JWST/NIRSpec MSA G395H spectroscopy, derive metallicities with self-consistent analytic prescriptions, and propagate the dust-extinction uncertainty into an asymmetric error budget via Monte Carlo simulations based on the observed Balmer decrements. Stellar masses come from BEAGLE SED fitting of JWST/NIRCam and UltraVISTA photometry. Results. We obtain five secure [O III]$λ$4363 detections and one upper limit, with 12+log(O/H) $\\approx$ 7.2-8.0. The weighted spectral stack yields 12+log(O/H) = $7.76^{+0.06}_{-0.05}$, ~0.26 dex higher than stacks of LAEs at similar redshifts from JWST surveys. However, the MZR fit gives a slope $γ$ = 0.232 +/- 0.214 and normalization $Z_0$ = 7.888 +/- 0.199, placing our sources below the established MZR of normal galaxies and recent protocluster baselines at $z\\sim5-7$. Conclusions. The higher metallicity relative to general LAEs suggests accelerated assembly driven by the overdensity, while the offset below the MZR points to a complex interplay between mass build-up and gas accretion. Since we target actively star-forming LAEs, we are likely capturing a phase of pristine gas inflow from the intergalactic medium that fuels star formation but dilutes the interstellar media of these protocluster members.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.01811",
  "author_total": 18,
  "authors": [
    {
      "name": "C. Moya-Sierralta"
    },
    {
      "name": "C. L. Martin"
    },
    {
      "name": "L. F. Barrientos"
    },
    {
      "name": "L. Infante"
    },
    {
      "name": "J. González-López"
    },
    {
      "name": "W. Hu"
    },
    {
      "name": "A. L. Faisst"
    },
    {
      "name": "Y. Harikane"
    },
    {
      "name": "A. M. Koekemoer"
    },
    {
      "name": "S. Malhotra"
    },
    {
      "name": "M. Ouchi"
    },
    {
      "name": "Z. Peng"
    },
    {
      "name": "J. Rhoads"
    },
    {
      "name": "J. Wang"
    },
    {
      "name": "J. R. Weaver"
    },
    {
      "name": "I. Wold"
    },
    {
      "name": "J. Yang"
    },
    {
      "name": "Z. Zheng"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3b89v2a2s0fq5.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.01811",
  "fulltext_url": null,
  "id": "3b89v2a2s0fq5",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.01811",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.01811",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3b89v2a2s0fq5.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2610.01811",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.01811"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Galaxy Protoclusters as Drivers of Cosmic Reionization: II. Te-Based Metallicities of Lyman-α Emitters",
  "title_text": "Galaxy Protoclusters as Drivers of Cosmic Reionization: II. Te-Based Metallicities of Lyman-α Emitters",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/3b89v2a2s0fq5",
  "venue": "arXiv",
  "versions": []
}