{
  "abstract": "The central engines of Little Red Dots (LRDs) may be “black hole stars” (BH*s), early stages of black hole growth characterized by dense gas envelopes. So far, the most direct evidence for BH*s comes from a handful of sources where the host galaxy is completely outshone as suggested by their remarkably steep Balmer breaks. Here we present a novel scheme to disentangle BH*s from their host galaxies assuming that the [OIII]5008Å line arises exclusively from the host. Using a sample of 98 LRDs ( z ≈ 2 − 9 ) with high quality NIRSpec/PRISM spectra, we demonstrate that the host-subtracted median stack displays a Balmer break > 2 × stronger than massive quiescent galaxies, with the rest-optical continuum resembling a blackbody-like SED ( K, erg s, au). We measure a steep Balmer decrement (H α /H β > 10 ) and numerous density-sensitive features (e.g., FeII, HeI, OI). These are hallmark signatures of dense gas envelopes, providing population-level evidence that BH*s indeed power LRDs. In the median LRD, BH*s account for ∼ 20 % of the UV emission, ∼ 50 % at the Balmer break, and ∼ 90 % at wavelengths longer than H α with the remainder arising from the host. BH*s preferentially reside in low-mass galaxies () undergoing recent starbursts, as evidenced by extreme emission line EWs (e.g., [OIII]5008Å ≈ 1100 Å, CIII] ≈ 12 Å), thereby favoring BH* origins linked to star-formation. We show V-shaped LRD selections are biased to high BH*/host fractions ( ≳ 60 % at 5500Å) – less dominant BH*s may be powering JWST’s blue broad-line AGN. We find BH*s are so commonplace and transient (duty cycle ∼ 1 % , lifetime ∼ 10 Myrs) that every massive black hole may have once shone as a BH*.",
  "abstract_shown": true,
  "affiliations": [
    "Massachusetts Institute of Technology",
    "Institute of Science and Technology Austria (ISTA)",
    "Max-Planck-Institut für Astronomie",
    "The University of Texas at Austin",
    "Princeton University",
    "Cosmic Dawn Center (DAWN)",
    "University of Copenhagen",
    "University of Geneva",
    "Durham University",
    "Leiden University",
    "University of Toronto",
    "École Polytechnique Fédérale de Lausanne",
    "The Pennsylvania State University",
    "Yale University",
    "The University of Texas at Dallas",
    "University of Cambridge",
    "Sorbonne Université",
    "NSF National Optical-Infrared Astronomy Research Laboratory"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 33,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Wendy Q. Sun",
      "orcid": "0009-0007-3791-7890"
    },
    {
      "affs": [
        0
      ],
      "name": "Rohan P. Naidu",
      "orcid": "0000-0003-3997-5705"
    },
    {
      "affs": [
        1
      ],
      "name": "Jorryt Matthee",
      "orcid": "0000-0003-2871-127X"
    },
    {
      "affs": [
        2
      ],
      "name": "Anna de Graaff",
      "orcid": "0000-0002-2380-9801"
    },
    {
      "affs": [
        3
      ],
      "name": "John Chisholm",
      "orcid": "0000-0002-0302-2577"
    },
    {
      "affs": [
        4
      ],
      "name": "Jenny E. Greene",
      "orcid": "0000-0002-5612-3427"
    },
    {
      "affs": [
        5,
        6,
        7
      ],
      "name": "Pascal A. Oesch",
      "orcid": "0000-0001-5851-6649"
    },
    {
      "affs": [
        1
      ],
      "name": "Alberto Torralba",
      "orcid": "0000-0001-5586-6950"
    },
    {
      "affs": [
        2
      ],
      "name": "Raphael E. Hviding",
      "orcid": "0000-0002-4684-9005"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Gabriel Brammer",
      "orcid": "0000-0003-2680-005X"
    },
    {
      "affs": [
        0
      ],
      "name": "Robert A. Simcoe",
      "orcid": "0000-0003-3769-9559"
    },
    {
      "affs": [
        8
      ],
      "name": "Sownak Bose",
      "orcid": "0000-0002-0974-5266"
    },
    {
      "affs": [
        9
      ],
      "name": "Rychard Bouwens",
      "orcid": "0000-0002-4989-2471"
    },
    {
      "affs": [
        10
      ],
      "name": "Pratika Dayal",
      "orcid": "0000-0001-8460-1564"
    },
    {
      "affs": [
        0
      ],
      "name": "Anna–Christina Eilers",
      "orcid": "0000-0003-2895-6218"
    },
    {
      "affs": [
        10
      ],
      "name": "Qinyue Fei",
      "orcid": "0000-0001-7232-5355"
    },
    {
      "affs": [
        3
      ],
      "name": "Lukas J. Furtak",
      "orcid": "0000-0001-6278-032X"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Rashmi Gottumukkala",
      "orcid": "0000-0003-0205-9826"
    },
    {
      "affs": [
        4
      ],
      "name": "Andy D. Goulding",
      "orcid": "0000-0003-4700-663X"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Kasper E. Heintz",
      "orcid": "0000-0002-9389-7413"
    },
    {
      "affs": [
        11
      ],
      "name": "Michaela Hirschmann",
      "orcid": "0000-0002-3301-3321"
    },
    {
      "affs": [
        3
      ],
      "name": "Vasily Kokorev",
      "orcid": "0000-0002-5588-9156"
    },
    {
      "affs": [
        12
      ],
      "name": "Joel Leja",
      "orcid": "0000-0001-6755-1315"
    },
    {
      "affs": [
        0
      ],
      "name": "Zhaoran Liu",
      "orcid": "0009-0002-8965-1303"
    },
    {
      "affs": [
        13
      ],
      "name": "Priyamvada Natarajan",
      "orcid": "0000-0002-5554-8896"
    },
    {
      "affs": [
        13
      ],
      "name": "Andrew D. Santarelli",
      "orcid": "0009-0007-4394-3366"
    },
    {
      "affs": [
        4
      ],
      "name": "David J. Setton",
      "orcid": "0000-0003-4075-7393"
    },
    {
      "affs": [
        14
      ],
      "name": "Aaron Smith",
      "orcid": "0000-0002-2838-9033"
    },
    {
      "affs": [
        15
      ],
      "name": "Sandro Tacchella",
      "orcid": "0000-0002-8224-4505"
    },
    {
      "affs": [
        16
      ],
      "name": "Marta Volonteri",
      "orcid": "0000-0002-3216-1322"
    },
    {
      "affs": [
        2
      ],
      "name": "Fabian Walter",
      "orcid": "0000-0003-4793-7880"
    },
    {
      "affs": [
        7
      ],
      "name": "Andrea Weibel",
      "orcid": "0000-0001-8928-4465"
    },
    {
      "affs": [
        17
      ],
      "name": "Christina C. Williams",
      "orcid": "0000-0003-2919-7495"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1xfthnve5y519.bib",
  "cited_by": 71,
  "doi": "10.33232/001c.162505",
  "fulltext_url": null,
  "id": "1xfthnve5y519",
  "issns": [
    "2565-6120"
  ],
  "landing_url": "https://doi.org/10.33232/001c.162505",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
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  "openalex": "W7162342206",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-05-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1xfthnve5y519.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:18Z",
      "native_id": "W7162342206",
      "source": "openalex",
      "url": "https://doi.org/10.33232/001c.162505"
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  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Galaxies: Formation, Evolution, Phenomena",
      "subfield": "galaxies"
    }
  ],
  "title": "Little Red Dot − Host Galaxy = Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot",
  "title_text": "Little Red Dot − Host Galaxy = Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot",
  "type": "peer-reviewed",
  "updated_at": "2026-11-09T13:21:01Z",
  "url": "https://research.draconitic.com/paper/1xfthnve5y519",
  "venue": "The Open Journal of Astrophysics",
  "versions": []
}