{
  "abstract": "We present a stacked JWST/NIRSpec spectrum of 104 galaxies at $λ_{\\rm rest}=1200\\unicode{x2013}2000\\;\\mathrm{\\mathring{A}}$ to study nebular emission and absorption from the interstellar medium (ISM) and stellar winds. The sample is drawn from known [O III] emitters with mean redshift $z=6.50$, absolute UV magnitude $M_\\mathrm{UV}=-20.7$, and stellar mass $M_{\\star}=10^{8.93}\\;\\mathrm{M_\\odot}$. The stacked continuum closely resembles lower-redshift Lyman Break Galaxy composites, with a few notable differences. Ly$\\;α$ has comparable strength and is redshifted relative to the [O III] systemic frame, consistent with production in gaseous outflows. High-ionization emission lines including O III], C III], and He II are slightly stronger than in lower-redshift stacks but exhibit narrow widths, disfavoring ionization from a broad-line AGN. Emission-line ratios slightly favor ionization by a hard stellar continuum, though a contribution from a narrow-line nuclear source cannot be strictly excluded. Numerous strong absorption lines at both high and low ionization are blueshifted by $\\sim200\\;\\mathrm{km\\,s^{-1}}$, again indicating outflows driven by stellar winds or entrained metal-enriched ISM. A simple model suggests that at $z\\sim6.5$ most star-forming galaxies are too young for winds at these velocities to propagate beyond $\\sim3\\unicode{x2013}9$ proper kpc, implying that the observed [O III] emitter population alone cannot explain the frequency of heavy-element absorbers seen in quasar spectra. In this picture, early enrichment of the intergalactic medium likely arises from undetected low-mass galaxies ($M_\\star\\sim10^5\\unicode{x2013}10^6\\;\\mathrm{M_\\odot}$) clustered around the more massive systems detected in JWST/NIRCam WFSS surveys.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.33154",
  "author_total": 7,
  "authors": [
    {
      "name": "David DePalma"
    },
    {
      "name": "Robert A. Simcoe"
    },
    {
      "name": "Anna-Christina Eilers"
    },
    {
      "name": "Rongmon Bordoloi"
    },
    {
      "name": "Daichi Kashino"
    },
    {
      "name": "Gauri Kotiwale"
    },
    {
      "name": "Jorryt Matthee"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9eepjqmv937p8.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.33154",
  "fulltext_url": null,
  "id": "9eepjqmv937p8",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.33154",
  "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.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7223961239",
  "pdf_url": "https://arxiv.org/pdf/2610.33154",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9eepjqmv937p8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2610.33154",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.33154"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "A Composite Rest-Frame UV Spectrum of Galaxies at $5.7 < z < 6.9$: Ionization, Outflows, and Implications for Intergalactic Metal Enrichment",
  "title_text": "A Composite Rest-Frame UV Spectrum of Galaxies at 5.7 < z < 6.9: Ionization, Outflows, and Implications for Intergalactic Metal Enrichment",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:17Z",
  "url": "https://research.draconitic.com/paper/9eepjqmv937p8",
  "venue": "arXiv",
  "versions": []
}