{
  "abstract": "The observed gravitational-wave background (GWB) spectrum is higher in amplitude than model predictions by a factor of 2–3. Using a semi-analytic model, we evaluate the effect of a high-scatter supermassive black hole (SMBH) scaling relation ( M BH – M bulge ) on models of the nanohertz GWB. By implementing an intrinsic scatter of the M BH – M bulge relation, which is larger at higher redshift, but matches local observations, we find that the amplitude of GWB models increases to be consistent with the low-frequency end of the GWB spectrum. This amplitude increase is not uniform across frequencies, a strongly evolving scatter preferentially increases the number density of the most massive SMBHs which, in the GWB spectrum, minimizes the strength of the low-frequency turnover. Our models with positively evolving intrinsic scatter can reproduce the electromagnetically observed overmassive SMBHs at 4 < z < 6 without changing the M BH – M bulge normalization though we find that including moderate normalization evolution marginally improves fits to the GWB data. We conclude that the M BH – M bulge relation which best describes the available GWB and electromagnetic data sets has intrinsic scatter that evolves as ε ( z ) = ε 0 + ( 0.56 ± 0.4 ) log 10 ( 1 + z ) and normalization that evolves as α ( z ) = α 0 (1 + z ) 0.84±0.35 . The results of this work imply that the M BH – M bulge relation we see today is not universal throughout cosmic time and that a diversity of seeding models and growth mechanisms may be at play in the early stages of SMBH–galaxy evolution.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2603.11167",
  "author_total": 112,
  "authors": [
    {
      "name": "Cayenne Matt"
    },
    {
      "name": "Kayhan Gültekin"
    },
    {
      "name": "Gabriella Agazie"
    },
    {
      "name": "Nikita Agarwal"
    },
    {
      "name": "Akash Anumarlapudi"
    },
    {
      "name": "Anne Archibald"
    },
    {
      "name": "Zaven Arzoumanian"
    },
    {
      "name": "Jeremy Baier"
    },
    {
      "name": "Paul Baker"
    },
    {
      "name": "Bence Bécsy"
    },
    {
      "name": "Laura Blecha"
    },
    {
      "name": "Adam Brazier"
    },
    {
      "name": "Paul Brook"
    },
    {
      "name": "Sarah Burke-Spolaor"
    },
    {
      "name": "Rand Burnette"
    },
    {
      "name": "Robin Case"
    },
    {
      "name": "J. Andrew Casey-Clyde"
    },
    {
      "name": "Maria Charisi"
    },
    {
      "name": "Shami Chatterjee"
    },
    {
      "name": "Tyler Cohen"
    },
    {
      "name": "James Cordes"
    },
    {
      "name": "Neil Cornish"
    },
    {
      "name": "Fronefield Crawford"
    },
    {
      "name": "H. Thankful Cromartie"
    },
    {
      "name": "Kathryn Crowter"
    },
    {
      "name": "Megan Decesar"
    },
    {
      "name": "Paul Demorest"
    },
    {
      "name": "Heling Deng"
    },
    {
      "name": "Lankeswar Dey"
    },
    {
      "name": "Timothy Dolch"
    },
    {
      "name": "Graham Doskoch"
    },
    {
      "name": "Elizabeth Ferrara"
    },
    {
      "name": "William Fiore"
    },
    {
      "name": "Emmanuel Fonseca"
    },
    {
      "name": "Gabriel Freedman"
    },
    {
      "name": "Emiko Gardiner"
    },
    {
      "name": "Nate Garver-Daniels"
    },
    {
      "name": "Peter Gentile"
    },
    {
      "name": "Kyle Gersbach"
    },
    {
      "name": "Joseph Glaser"
    },
    {
      "name": "Deborah Good"
    },
    {
      "name": "C. Harris"
    },
    {
      "name": "Jeffrey Hazboun"
    },
    {
      "name": "Ross Jennings"
    },
    {
      "name": "Aaron Johnson"
    },
    {
      "name": "Megan Jones"
    },
    {
      "name": "David Kaplan"
    },
    {
      "name": "Anala Kavumkandathil Sreekumar"
    },
    {
      "name": "Luke Zoltan Kelley"
    },
    {
      "name": "Matthew Kerr"
    },
    {
      "name": "Joey Key"
    },
    {
      "name": "Nima Laal"
    },
    {
      "name": "Michael Lam"
    },
    {
      "name": "William Lamb"
    },
    {
      "name": "Bjorn Larsen"
    },
    {
      "name": "T. Joseph W. Lazio"
    },
    {
      "name": "Natalia Lewandowska"
    },
    {
      "name": "Tingting Liu"
    },
    {
      "name": "Duncan Lorimer"
    },
    {
      "name": "Jing Luo"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1jheztqxfva66.bib",
  "cited_by": 0,
  "doi": "10.3847/1538-4357/ae801e",
  "fulltext_url": null,
  "id": "1jheztqxfva66",
  "issns": [
    "0004-637X",
    "1538-4357"
  ],
  "landing_url": "https://hal.science/hal-05842592v1",
  "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": [
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7135207382",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-07-15",
  "publisher": "American Astronomical Society",
  "ris": "https://research.draconitic.com/paper/1jheztqxfva66.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:02Z",
      "native_id": "hal-05842592",
      "source": "hal",
      "url": "https://hal.science/hal-05842592v1"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Galaxies: Formation, Evolution, Phenomena",
      "subfield": "galaxies"
    }
  ],
  "title": "Gravitational-wave Measurement of the M BH – M bulge Intrinsic Scatter at High Redshift",
  "title_text": "Gravitational-wave Measurement of the M BH – M bulge Intrinsic Scatter at High Redshift",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:02Z",
  "url": "https://research.draconitic.com/paper/1jheztqxfva66",
  "venue": "The Astrophysical Journal",
  "versions": []
}