{
  "abstract": "We present the first cosmological model for the lifecycle and luminous properties of PAHs in galaxies as they evolve from z=6-->0. We model 40 zoom-in galaxies, coupled with an on-the-fly model for the evolution of dust grains in the ISM. We approximate PAHs as ultrasmall (a < 13 Angstrom) carbonaceous dust grains, and couple this model with single-photon excitation calculations to compute the emergent mid-infrared spectra. (1) If we assume that dust is large upon formation, then PAHs are naturally able to form in situ in the ISM via grain-grain shattering. Interstellar collision velocities increase in low density, diffuse gas in our model; as galaxies evolve, the increase in fractional mass of diffuse gas drives an increase in grain-grain collision velocities and a corresponding rise in the PAH mass fraction (qPAH) from ~5 x 10^{-4} at z~4 to ~10^{-2} at z~0. (2) Increased PAH production in the diffuse ISM results in an inverse relationship between qPAH and the molecular gas fraction. (3) The PAH light-to-mass ratio scales linearly with the radiation field intensity (LPAH/MPAH ~ G_0) but anti-correlates with qPAH, because high-Sigma_SFR galaxies have a denser ISM that suppresses shattering. This means the physical qPAH and observed LPAH/LFIR do not evolve in lockstep. (4) The PAH-metallicity relationship (PZR) arises naturally in this framework: galaxies enrich and grow their diffuse ISM fraction simultaneously, linking rising metallicity to rising qPAH. Our models represent the first to reproduce the PZR observed across z=0-2. (5) The LPAH-SFR and LPAH-M_mol relations emerge from two effects: more massive galaxies have larger PAH reservoirs, and higher-SFR galaxies excite their PAHs more efficiently per unit mass. Taken together, these results suggest that grain-grain shattering in the diffuse ISM is the main driver behind the evolution of cosmic PAH abundances.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2606.20809",
  "author_total": 19,
  "authors": [
    {
      "name": "Desika Narayanan"
    },
    {
      "name": "Paul Torrey"
    },
    {
      "name": "Massimiliano Parente"
    },
    {
      "name": "Grant Donnelly"
    },
    {
      "name": "Dhruv Zimmerman"
    },
    {
      "name": "Alex Garcia"
    },
    {
      "name": "Helena Richie"
    },
    {
      "name": "J. -D. T. Smith"
    },
    {
      "name": "Brandon Hensley"
    },
    {
      "name": "Federico Marinacci"
    },
    {
      "name": "Jed McKinney"
    },
    {
      "name": "Alexandra Pope"
    },
    {
      "name": "Gergo Popping"
    },
    {
      "name": "Laura Sales"
    },
    {
      "name": "Karin Sandstrom"
    },
    {
      "name": "Ethan Savitch"
    },
    {
      "name": "Irene Shivaei"
    },
    {
      "name": "Justin Spilker"
    },
    {
      "name": "Corey Whitcomb"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6pr7r5v5b5ehg.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.20809",
  "fulltext_url": null,
  "id": "6pr7r5v5b5ehg",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.20809",
  "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/2606.20809",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6pr7r5v5b5ehg.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:22Z",
      "native_id": "2606.20809",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.20809"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "The Lifecycle and Emission Properties of PAHs in Cosmological Hydrodynamic Galaxy Formation Simulations",
  "title_text": "The Lifecycle and Emission Properties of PAHs in Cosmological Hydrodynamic Galaxy Formation Simulations",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:44Z",
  "url": "https://research.draconitic.com/paper/6pr7r5v5b5ehg",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.33232/001c.172863",
      "pid": "fwrvh0fsad9pa",
      "relation": "published-as",
      "title": "The Lifecycle and Emission Properties of PAHs in Cosmological Hydrodynamic Galaxy Formation Simulations",
      "venue": "The Open Journal of Astrophysics"
    }
  ]
}