{
  "abstract": "We present a flexible implementation of non-equilibrium chemical networks with the $\\texttt{KROME}$ framework, coupled to a nonlocal variable Eddington tensor-closed radiation transport scheme ($\\texttt{VETTAM}$). Our fiducial network is designed to explicitly capture the formation pathways of important molecular species such as CO, OH, and $\\rm H_2O$, intermediaries like $\\rm H_3^+$, and the destruction of these species through photon and cosmic-ray dissociation. We validate our scheme through benchmark tests, and demonstrate its success in 1D and 3D problems covering a broad range of metallicities ($0 \\leq Z \\lesssim \\rm Z_{\\odot}$) and densities ($n \\lesssim 10^{17} \\, \\rm cm^{-3}$). We confirm earlier works that suggest that OH and $\\rm H_2O$ are the key molecular species in dense gas ($n \\gtrsim 10^{5} \\, \\rm cm^{-3}$) for $Z\\lesssim 0.01 \\rm Z_{\\odot}$, dominate the cooling at these densities, and demonstrate that our scheme can reproduce their abundances with similar accuracy as dedicated static photo-dissociation region (PDR) codes. We also find that the dominant fine-structure coolant in dense ($n \\gtrsim 10^3 \\, \\, \\rm cm^{-3}$) PDRs transitions from CI to CII to OI at increasingly lower $Z$. Finally, we find that in turbulent media, rapid mixing at PDR interfaces renders the chemical species out of equilibrium, and show that this could potentially alleviate the long-standing problem of (static) PDR models producing excess CI in the diffuse ISM over UV absorption-line measurements. We conclude by presenting and comparing with alternative implementations of reduced but faster chemical networks in our scheme, discussing the problem-dependent performance-accuracy tradeoffs and future prospects.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.17577",
  "author_total": 4,
  "authors": [
    {
      "name": "Shyam H. Menon"
    },
    {
      "name": "Piyush Sharda"
    },
    {
      "name": "Blakesley Burkhart"
    },
    {
      "name": "Tommaso Grassi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4jdxy7mfwr4b7.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.17577",
  "fulltext_url": null,
  "id": "4jdxy7mfwr4b7",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.17577",
  "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"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Astrophysics and Star Formation Studies"
    ]
  ],
  "openalex": "W7221807990",
  "pdf_url": "https://arxiv.org/pdf/2610.17577",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4jdxy7mfwr4b7.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:11Z",
      "native_id": "2610.17577",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.17577"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "Non-equilibrium chemistry and radiation hydrodynamics in metal-poor and metal-rich interstellar gas",
  "title_text": "Non-equilibrium chemistry and radiation hydrodynamics in metal-poor and metal-rich interstellar gas",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:11Z",
  "url": "https://research.draconitic.com/paper/4jdxy7mfwr4b7",
  "venue": "arXiv",
  "versions": []
}