{
  "abstract": "JWST has uncovered a population of compact high-redshift galaxies, 'little red dots' (LRDs), exhibiting broad Balmer emission lines that often show narrow absorption features and strong Balmer breaks - spectral signatures attributed to dense gas surrounding rapidly growing black holes, but whose small-scale structure remains unknown. A striking feature of LRD spectra is that the H$β$ absorption is systematically deeper than H$α$, yet in any homogeneous gas this ordering is physically impossible. Here we model the H$α$ and H$β$ line profiles using radiative transfer simulations for 11 LRDs with JWST sensitive high resolution spectroscopy, and independently constrain the $n=2$ hydrogen column density, $N_{\\rm HI,\\mathit{n}=2}$, from the Balmer-break continuum. We find that the $N_{\\rm HI,\\mathit{n}=2}$ from H$α$ in a homogeneous medium cannot reproduce the observed H$β$ absorption in several objects, and that this $N_{\\rm HI,\\mathit{n}=2}$ typically falls two orders of magnitude below the lower bound set by the Balmer break. Both tensions are simultaneously resolved by a multiphase medium of dense clumps within diffuse hot ionized gas. This multiphase gas structure is a necessary ingredient for any viable LRD model, regardless of the nature of the central engine.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.34552",
  "author_total": 4,
  "authors": [
    {
      "name": "Seok-Jun Chang"
    },
    {
      "name": "Max Gronke"
    },
    {
      "name": "Jorryt Matthee"
    },
    {
      "name": "Charlotte Mason"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3c6y3nzdkf774.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.34552",
  "fulltext_url": null,
  "id": "3c6y3nzdkf774",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.34552",
  "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/2610.34552",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3c6y3nzdkf774.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2610.34552",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.34552"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Multiphase Gas Structure in JWST Little Red Dots",
  "title_text": "Multiphase Gas Structure in JWST Little Red Dots",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/3c6y3nzdkf774",
  "venue": "arXiv",
  "versions": []
}