{
  "abstract": "GRB 221009A, the Brightest Of All Time (BOAT), presents a challenge for afterglow modelling due to its low Galactic latitude and consequent high line-of-sight extinction. This has led to a wide range of conflicting values for the optical spectral index and dust extinction in the literature. We present a re-analysis of the afterglow spectra, using VLT X-Shooter data at 0.5, 4, and 10.5 days, and JWST NIRSpec/MIRI data at 13.3 days post-burst. We fit the data with single and smoothly broken power-law models and perform a joint fit with a double smoothly broken power-law (DSBPL) across all epochs. Our analysis reveals a strong degeneracy between the assumed extinction and the inferred intrinsic spectral index, particularly in the optical, explaining the diversity of previous results. The joint DSBPL fit yields a total line-of-sight extinction of AV = 4.40 ± 0.01 and a blue continuum, with an intrinsic spectral index of β = 0.447 ± 0.001. Although marginally preferred by the spectral fits, a wind medium can be rejected by the temporal evolution of the afterglow light curve. The fit spectral index and temporal decline are only consistent with a uniform density medium if an early jet break at ∼0.5-1.0 days is invoked. Our results imply a hard electron distribution index of p = 1.89 < 2, challenging standard particle acceleration models and suggesting a narrow, energetic jet core dominates the early optical-to-X-ray emission.",
  "abstract_shown": true,
  "affiliations": [
    "Astrophysics Research Institute, Liverpool John Moores University , IC2 Liverpool Science Park, 146 Brownlow Hill, Liverpool, L3 5RF ,",
    "School of Systems Information Science, Future University Hakodate , Hakodate, Hokkaido 041-8655 ,",
    "Astronomical Institute, Graduate School of Science , Tohoku University, Sendai 980-8578 ,",
    "Radboud University Department of Astrophysics/IMAPP, , 6525 AJ Nijmegen ,",
    "University of Warwick Department of Physics, , Coventry, CV4 7AL ,",
    "School of Physics and Astronomy, University of Leicester, University Road, Leicester , LE1 7RH ,",
    "Space Science Data Center (SSDC) - Agenzia Spaziale Italiana (ASI) , I-00133 Roma ,",
    "DARK, Niels Bohr Institute, University of Copenhagen , Jagtvej 155A, 2200 Copenhagen ,",
    "INAF, Osservatorio Astronomico di Capodimonte , Salita Moiariello 16, I-80121 Naples ,"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Nguyen M Khang",
      "orcid": "0000-0001-9657-8728"
    },
    {
      "affs": [
        0
      ],
      "name": "Gavin P Lamb",
      "orcid": "0000-0001-5169-4143"
    },
    {
      "affs": [
        0
      ],
      "name": "Helena-M S Grabham"
    },
    {
      "affs": [
        0
      ],
      "name": "Conor M B Omand",
      "orcid": "0000-0002-9646-8710"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Hamid Hamidani"
    },
    {
      "affs": [
        3,
        4
      ],
      "name": "Andrew J Levan"
    },
    {
      "affs": [
        5
      ],
      "name": "Nial R Tanvir"
    },
    {
      "affs": [
        6
      ],
      "name": "Valerio D’Elia"
    },
    {
      "affs": [
        7,
        8
      ],
      "name": "Luca Izzo"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8aceyvh5q1eat.bib",
  "cited_by": 0,
  "doi": "10.1093/mnras/stag2053",
  "fulltext_url": null,
  "id": "8aceyvh5q1eat",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2053/9005956",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
  "openalex": null,
  "pdf_url": "https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag2053/72655241/stag2053.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-31",
  "publisher": "Oxford University Press (OUP)",
  "ris": "https://research.draconitic.com/paper/8aceyvh5q1eat.ris",
  "sources": [
    {
      "first_seen": "2026-11-01T00:20:40Z",
      "native_id": "10.1093/mnras/stag2053",
      "source": "crossref",
      "url": "https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2053/9005956"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "journal-openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "title": "JWST’s Dusty Blue BOAT - GRB 221009A",
  "title_text": "JWST’s Dusty Blue BOAT - GRB 221009A",
  "type": "peer-reviewed",
  "updated_at": "2026-11-01T00:20:40Z",
  "url": "https://research.draconitic.com/paper/8aceyvh5q1eat",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}