{
  "abstract": "We present JWST/MIRI (Proposal ID 4297) medium-resolution integral field spectroscopy of five H II regions in the nearby spiral galaxy M33, obtained from the Mikulski Archive for Space Telescopes (MAST). The fully calibrated Level-3 spectral cubes provide continuous wavelength coverage from 6.5 - 20.9~$μ$m, enabling analysis of polycyclic aromatic hydrocarbon (PAH) emission, ionic fine-structure lines, and warm molecular hydrogen. The spectra show prominent PAH bands at 7.7, 8.6, and 11.3~$μ$m, multiple H$_2$ rotational transitions, and hydrogen recombination lines. H$_2$ rotational diagrams yield warm molecular gas temperatures of $\\sim316$ - $407$~K. The detected [Ne II], [Ne III], [S III], and [S IV] lines yield ionization indices of $-1.41$ to $+0.98$. The PAH ionization fraction shows no clear dependence on radiation hardness, consistent with previous Spitzer results. Unlike previous work, we find no clear correlation between the 7.7/11.2 and 8.6/11.2~$μ$m PAH ratios, while the 7.7/11.2~$μ$m ratio shows a moderate negative correlation with metallicity, possibly due to our small sample ($N=5$). The PAH-to-VSG ratio decreases with increasing radiation hardness. We derive the ionization parameter $γ$, far-ultraviolet radiation field, and PAH charge state, finding a predominantly cationic PAH population ($\\sim75%$) despite [Ne III]/[Ne II] $<1$. The lack of a one-to-one correspondence between $γ$ and the 7.7/11.2~$μ$m ratio suggests that PAH ionization is influenced by additional environmental factors. Given the limited sample, these trends are suggestive rather than statistically definitive.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.22846",
  "author_total": 3,
  "authors": [
    {
      "name": "Puja Porel"
    },
    {
      "name": "Archana Soam"
    },
    {
      "name": "Saikhom Pravash"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3cwwpb5zt186q.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.22846",
  "fulltext_url": null,
  "id": "3cwwpb5zt186q",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.22846",
  "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",
      "3103|Astrophysics and Star Formation Studies"
    ]
  ],
  "openalex": "W7214047089",
  "pdf_url": "https://arxiv.org/pdf/2609.22846",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3cwwpb5zt186q.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.22846",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.22846"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Mid-Infrared Diagnostics of PAH Processing and Radiation Fields in M33 H II Regions with JWST/MIRI",
  "title_text": "Mid-Infrared Diagnostics of PAH Processing and Radiation Fields in M33 H II Regions with JWST/MIRI",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/3cwwpb5zt186q",
  "venue": "arXiv",
  "versions": []
}