{
  "abstract": "Recent James Webb Space Telescope (JWST) measurements quantify the fraction of ultraviolet-selected galaxies showing detectable Lyman-alpha (Ly-$α$) lines at $z \\sim 6-14$. These Ly-$α$ fractions are partly shaped by Ly-$α$ scattering from neutral hydrogen in the surrounding intergalactic medium (IGM), and so the observed Ly-$α$ fraction evolution can inform our understanding of the reionization history and the size distribution of ionized bubbles during reionization. We compare the JWST measurements with Ly-$α$ transmission calculations based on both the THESAN reionization simulations and a flexible semi-analytic model. In each case, we calibrate a sub-grid model for the intrinsic Ly-$α$ emission lines emerging from the interstellar medium (ISM) and circumgalactic medium (CGM) of the host galaxies using empirical estimates of the Ly-$α$ equivalent width (EW) distributions at $z \\sim 6$. We find that the reionization history and bubble sizes in THESAN yield good agreement with current JWST Ly-$α$ fraction observations, with a reduced $χ^2_ν= 0.4-1.2$. Our semi-analytic models and THESAN Ly-$α$ transmission calculations agree well, allowing us to explore a wide range of reionization models. We derive $1σ$ bounds on the average mass-weighted neutral fractions of: $\\langle x_{\\mathrm{HI}} \\rangle$ = $0.38^{+0.14}_{-0.38}$ ($0.52^{+0.09}_{-0.21}$), $0.57^{+0.23}_{-0.57}$ ($0.68^{+0.12}_{-0.39}$), and $0.93^{+0.05}_{-0.17}$ ($0.89^{+0.11}_{-0.15}$) at $z \\sim$ 7, 8, and 11, based on the Ly-$α$ fraction measurements with EW $>25\\,\\mathring{\\rm A}$ ($>10\\,\\mathring{\\rm A}$).",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.40363",
  "author_total": 3,
  "authors": [
    {
      "name": "Aritra Kundu"
    },
    {
      "name": "Adam Lidz"
    },
    {
      "name": "Guochao Sun"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/89x6hm7bsdpe0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.40363",
  "fulltext_url": null,
  "id": "89x6hm7bsdpe0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.40363",
  "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.CO"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7215060041",
  "pdf_url": "https://arxiv.org/pdf/2609.40363",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/89x6hm7bsdpe0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:49Z",
      "native_id": "2609.40363",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.40363"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Probing the Reionization History and Bubble Sizes with JWST Lyman-$α$ Fraction Measurements",
  "title_text": "Probing the Reionization History and Bubble Sizes with JWST Lyman-α Fraction Measurements",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:49Z",
  "url": "https://research.draconitic.com/paper/89x6hm7bsdpe0",
  "venue": "arXiv",
  "versions": []
}