{
  "abstract": "The wind-collision regions of massive colliding-wind binaries (CWBs) accelerate relativistic particles, as shown by their non-thermal radio synchrotron and, in $η$ Car, hard X-ray emission. Whether CWBs emit GeV $γ$rays as a population is unknown: only $η$ Car is unambiguously detected by the Fermi Large Area Telescope (LAT). We analyze 17.8 yr of Fermi-LAT data above 1 GeV (where the sharp point-spread function controls plane confusion) at the 61 confirmed (list A) particle-accelerating CWBs (PACWBs) of De Becker & Raucq, using a two-dimensional (photon index $\\times$ flux) likelihood scan against 200 control fields matched in latitude, local source density, and diffuse intensity. Removing systems whose lines of sight coincide with bright catalogue $γ$-ray sources leaves a clean, mutually isolated sample of 6, whose stack is consistent with the control-field null ($p=0.83$): no evidence for collective GeV emission. Retaining those systems instead yields a spurious $\\gtrsim3.5σ$ excess from chance catalogue coincidences, a caveat for Galactic-plane stacking. The resulting 95% limit on the mean per-source flux, $F(>1\\,\\mathrm{GeV})\\lesssim1.1\\times10^{-11}~\\mathrm{ph\\,cm^{-2}\\,s^{-1}} (Γ=2)$, implies a $γ$-ray production efficiency $η=L_γ/L_{\\rm wind}\\lesssim4\\times10^{-6}\\,(d/\\mathrm{kpc})^2$, about two orders of magnitude below $η$ Car at the sample's median distance. A representative single-zone model then bounds the electron acceleration efficiency in CWB wind-collision regions unless their magnetic field is comparable to or above the magnetic-photon equipartition value. Among the high-latitude systems accessible to a clean stack, $η$ Car thus appears to be a singular object rather than the brightest member of an emerging population.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: JCAP08(2026)067",
  "arxiv": "2607.05102",
  "author_total": 1,
  "authors": [
    {
      "name": "Youngwan Son"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9bp22wrrcqx1e.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.05102",
  "fulltext_url": null,
  "id": "9bp22wrrcqx1e",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.05102",
  "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.HE"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2607.05102",
  "pmcid": null,
  "pmid": null,
  "published": "2026-07-06",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9bp22wrrcqx1e.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "2607.05102",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.05102"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "An 18-year Fermi-LAT stacking limit on GeV $γ$-ray emission from particle-accelerating colliding-wind binaries",
  "title_text": "An 18-year Fermi-LAT stacking limit on GeV γ-ray emission from particle-accelerating colliding-wind binaries",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/9bp22wrrcqx1e",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1088/1475-7516/2026/08/067",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}