{
  "abstract": "We use all-configuration VLA data at 3.3 cm with a physical resolution of ~2000 AU to infer the embedded zero-age massive stellar population of the W49A protocluster, as traced by its compact, ultracompact (UC), and hypercompact (HC) H II regions. Our method consists of visual source identification, the derivation of stellar ionizing-photon rates from the observed emission measure, and the further derivation of stellar masses and luminosities using state-of-the-art stellar calibrations. Considering the 101 robust detections, maximum-likelihood estimation fitting of the high-mass end (M > 10.9 M_\\odot) of the sample yields power-law slopes Gamma >= 2.40 for the logarithmic representation of the stellar initial mass function (IMF): dN/d(log M) proportional to M^{-Gamma}. The result is robust considering different assumptions for the ionizing stellar systems. The slopes remain at Gamma >= 1.88 after correction for optical depth effects at 3.3 cm. Therefore, the inferred distribution of stellar masses presents a clear deficit in the high-mass end as compared to the standard stellar IMF (Gamma = 1.35). We propose that this is due to a shorter lifetime of the radio-detected H II regions produced by higher-mass stars, but evolutionary effects in the mass distribution of star formation within embedded protoclusters cannot be discarded.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.05453",
  "author_total": 17,
  "authors": [
    {
      "name": "M. Juárez-Gama"
    },
    {
      "name": "R. Galván-Madrid"
    },
    {
      "name": "G. Suárez"
    },
    {
      "name": "C. G. De Pree"
    },
    {
      "name": "J. J. Tobin"
    },
    {
      "name": "G. Bruzual"
    },
    {
      "name": "A. Ginsburg"
    },
    {
      "name": "J. E. Mendoza-Torres"
    },
    {
      "name": "H. B. Liu"
    },
    {
      "name": "D. Wilner"
    },
    {
      "name": "T. Nony"
    },
    {
      "name": "A. Parra-López"
    },
    {
      "name": "R. Rivera-Soto"
    },
    {
      "name": "A. F. McLeod"
    },
    {
      "name": "N. Cunningham"
    },
    {
      "name": "X. Lu"
    },
    {
      "name": "E. F. Jiménez-Andrade"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7gk239cak7rgn.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.05453",
  "fulltext_url": null,
  "id": "7gk239cak7rgn",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.05453",
  "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.SR"
    ],
    [
      "openalex",
      "3103|Astrophysics and Star Formation Studies"
    ]
  ],
  "openalex": "W7201859971",
  "pdf_url": "https://arxiv.org/pdf/2608.05453",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7gk239cak7rgn.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:31Z",
      "native_id": "2608.05453",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.05453"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "The Zero-Age Massive Stellar Population of W49A from VLA Observations",
  "title_text": "The Zero-Age Massive Stellar Population of W49A from VLA Observations",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:31Z",
  "url": "https://research.draconitic.com/paper/7gk239cak7rgn",
  "venue": "arXiv",
  "versions": []
}