{
  "abstract": "We present a census of massive eclipsing binary (EB) candidates in the Whirlpool Galaxy (M51), a face-on spiral galaxy at 7.5 Mpc with $Z\\sim Z_\\odot$. Using 34 epochs of red-optical Hubble Space Telescope (HST) photometry and a single epoch of broadband UV-optical photometry, we identify 173 massive EB candidates ($>5~{\\rm M_\\odot}$) with orbital periods $P_{\\rm orb}$=1-30 days. The sample traces young stellar populations across the spiral arms of M51. Joint light-curve and spectral energy distribution fits for 136 systems yield binaries spanning $T_{\\rm eff}=10{,}000$-$50{,}000$ K, $R=7$-$66~{\\rm R_\\odot}$, and masses of $5$-$120~{\\rm M_\\odot}$. We use detailed injection-recovery simulations to quantify the survey's completeness and infer intrinsic properties of the massive binary population. At the population level, we infer a close-binary fraction of $f_{\\rm close}=27.4\\pm7.1\\%$ for $2\\leq P_{\\rm orb}/{\\rm d}<20$ and $0.1\\leq q\\leq1$. Over the same period range, the intrinsic period distribution is consistent with being log-uniform, ${\\rm d}N/{\\rm d}\\log P_{\\rm orb}\\propto P_{\\rm orb}^π$ with $π=0.29\\pm0.32$. These demographics broadly match those of massive-star populations in the Milky Way, LMC, and SMC, with tentative evidence for a lower close-binary fraction at lower metallicity. Across the $\\sim0.2$-$1.1~Z_\\odot$ range spanned by these galaxies, the overall similarities suggest that the formation of close massive binaries depends only weakly on metallicity. Our survey establishes EBs as a powerful tool for measuring massive-binary demographics beyond the Local Group and provides a rich panchromatic census of $\\sim$100,000 luminous stars and variables in M51.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.19268",
  "author_total": 6,
  "authors": [
    {
      "name": "Cheyanne Shariat"
    },
    {
      "name": "Kareem El-Badry"
    },
    {
      "name": "Maude Gull"
    },
    {
      "name": "Daniel R. Weisz"
    },
    {
      "name": "Charlie Conroy"
    },
    {
      "name": "Alessandro Savino"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/btd38m5h1j4hg.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.19268",
  "fulltext_url": null,
  "id": "btd38m5h1j4hg",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.19268",
  "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"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7213580900",
  "pdf_url": "https://arxiv.org/pdf/2609.19268",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/btd38m5h1j4hg.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.19268",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.19268"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "A census of massive eclipsing binaries in the Whirlpool Galaxy",
  "title_text": "A census of massive eclipsing binaries in the Whirlpool Galaxy",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:19Z",
  "url": "https://research.draconitic.com/paper/btd38m5h1j4hg",
  "venue": "arXiv",
  "versions": []
}