Extreme properties of a compact and massive accreting black hole host in the first 500 Myr
Little red dots (LRDs) are a high redshift galaxy population. Despite their high number densities, their nature is still uncertain. Here we present CANUCS-LRD-z8.6, a spectroscopically confirmed little red dot at a spectroscopic redshift of z<sub>spec</sub> = 8.6319, hosting an active galactic nucleus. Its spectrum exhibits broad Hβλ4863 Å emission, high-ionization lines (C iv, N iv]), high electron temperature, which are indicative of active galactic nucleus activity, and low metallicity (Z < 0.1-0.2Z<sub>⊙</sub>). The inferred black hole mass, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow> <mml:mrow><mml:mi>BH</mml:mi></mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup><mml:mrow><mml:mn>0</mml:mn></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>0.4</mml:mn></mml:mrow> <mml:mrow><mml:mo>+</mml:mo> <mml:mn>0.6</mml:mn></mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow> <mml:mrow><mml:mn>8</mml:mn></mml:mrow> </mml:msup> <mml:mspace></mml:mspace> <mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow> <mml:mrow><mml:mo>⊙</mml:mo></mml:mrow> </mml:msub> </mml:math> , poses strong constraints on current black hole formation models and simulations. Additionally, its black hole is over-massive relative to its host, deviating from local M<sub>BH</sub> - M<sub>*</sub> relations, suggesting an early, rapid black hole growth preceding that of its galaxy. CANUCS-LRD-z8.6 may represent an evolutionary link between early massive black holes and the luminous quasars observed at z = 6.
Authors
- Gaël Noirot
- Anishya Harshan (ORCID: https://orcid.org/0000-0001-9414-6382)
- Seiji Fujimoto (ORCID: https://orcid.org/0000-0001-7201-5066)
- Francesco D’Eugenio (ORCID: https://orcid.org/0000-0003-2388-8172)
- Maruša Bradač (ORCID: https://orcid.org/0000-0001-5984-0395)
- S. Gallerani (ORCID: https://orcid.org/0000-0002-7200-8293)
- Vladan Markov (ORCID: https://orcid.org/0000-0002-5694-6124)
- G. Desprez (ORCID: https://orcid.org/0000-0001-8325-1742)
- Roberto Abraham (ORCID: https://orcid.org/0000-0002-4542-921X)
- Adam Muzzin (ORCID: https://orcid.org/0000-0002-9330-9108)
- Maulik Bhatt (ORCID: https://orcid.org/0000-0002-0287-7485)
- Chris J. Willott (ORCID: https://orcid.org/0000-0002-4201-7367)
- Ghassan T. E. Sarrouh (ORCID: https://orcid.org/0000-0001-8830-2166)
- Vicente Estrada-Carpenter (ORCID: https://orcid.org/0000-0001-8489-2349)
- Mirko Curti (ORCID: https://orcid.org/0000-0002-2678-2560)
- Yoshihisa Asada (ORCID: https://orcid.org/0000-0003-3983-5438)
- Rosa M. Mérida (ORCID: https://orcid.org/0000-0001-8115-5845)
- Kartheik G. Iyer (ORCID: https://orcid.org/0000-0001-9298-3523)
- Roberta Tripodi (ORCID: https://orcid.org/0000-0002-9909-3491)
- Marcin Sawicki (ORCID: https://orcid.org/0000-0002-7712-7857)
- Gaia Gaspar (ORCID: https://orcid.org/0000-0001-9293-4449)
- Nicholas S. Martis (ORCID: https://orcid.org/0000-0003-3243-9969)
- Victoria Strait (ORCID: https://orcid.org/0000-0002-6338-7295)
- Lamiya Mowla (ORCID: https://orcid.org/0000-0002-8530-9765)
- Gabriel Brammer (ORCID: https://orcid.org/0000-0003-2680-005X)
- Vieri Cammelli (ORCID: https://orcid.org/0000-0002-2070-9047)
- Fabio Di Mascia (ORCID: https://orcid.org/0000-0002-9263-7900)
- Ilias Goovaerts
- Gregor Rihtaršič (ORCID: https://orcid.org/0009-0009-4388-898X)
- Jasbir Singh
- Jon Judež (ORCID: https://orcid.org/0009-0000-2101-1938)
- Giordano Felicioni (ORCID: https://orcid.org/0009-0001-0778-9038)
Institutions
- Herzberg Institute of Astrophysics (CA)
- University of Copenhagen (DK)
- Space Telescope Science Institute (US)
- European Southern Observatory (DE)
- University of Trieste (IT)
- University of Ljubljana (SI)
- Scuola Normale Superiore (IT)
- University of Groningen (NL)
- University of Toronto (CA)
- Wellesley College (US)
- York University (CA)
- Kyoto University (JP)
- University of Cambridge (GB)
- Brera Astronomical Observatory (IT)
- Bridge University (SS)
- Canadian Institute for Theoretical Astrophysics (CA)
- Kyoto University of Education (JP)
- Institute for Fundamental Physics of the Universe (IT)
- Saint Mary's University (CA)
- Columbia University (US)
- The University of Texas at Austin (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2025-11-19
- DOI
- https://doi.org/10.1038/s41467-025-65070-x
- Citations
- 6
- Primary Topic
- Astrophysical Phenomena and Observations
- Type
- article
- Field-Weighted Citation Impact
- 6.93
Funders
- National Aeronautics and Space Administration
- Space Telescope Science Institute
- Canadian Space Agency
- Natural Sciences and Engineering Research Council of Canada
- Japan Society for the Promotion of Science