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Peer-reviewedCC BYNature

A direct black-hole mass measurement in a little red dot at high redshift

  • Ignas Juodžbalis1,2
  • C. Marconcini3,4
  • Francesco D’Eugenio5,6
  • R. Maiolino5,7,6
  • ALESSANDRO MARCONI3,4
  • Hannah Übler8
  • Jan Scholtz5,6
  • Xihan Ji5,6
  • Gareth C. Jones5,6
  • Michele Perna9
  • Santiago Arribas9
  • Jake S. Bennett10
28 more authors
  • Volker Bromm11
  • Andrew J. Bunker12
  • Stefano Carniani13
  • S. Charlot14
  • G. Cresci3
  • Pratika Dayal15,16
  • Eiichi Egami17
  • A. C. Fabian18
  • Kohei Inayoshi19
  • Yuki Isobe5,6,20
  • Lucy R. Ivey5,6
  • Sophie Koudmani21,22
  • Nicolas Laporte23
  • Jianwei Lyu24
  • Jianwei Lyu17
  • Giovanni Mazzolari8
  • Stephanie Monty18
  • Eleonora Parlanti13
  • Pablo G. Pérez‐González9
  • Brant E. Robertson25
  • Raffaella Schneider26
  • Debora Sijacki18,6
  • Sandro Tacchella5,6
  • Alessandro Trinca27
  • Rosa Valiante28
  • Marta Volonteri14
  • Joris Witstok29,30
  • Saiyang Zhang31,32
32 affiliations
  1. 1Cavendish Laboratory, University of Cambridge, Cambridge, UK. [email protected]
  2. 2Kavli Institute for Cosmology, University of Cambridge, Cambridge, UK. [email protected]
  3. 3INAF - Arcetri Astrophysical Observatory, Florence, Italy
  4. 4Università di Firenze, Dipartimento di Fisica e Astronomia, Florence, Italy
  5. 5Cavendish Laboratory, University of Cambridge, Cambridge, UK
  6. 6Kavli Institute for Cosmology, University of Cambridge, Cambridge, UK
  7. 7Department of Physics and Astronomy, University College London, London, UK
  8. 8Max-Planck-Institut für extraterrestrische Physik, Garching, Germany
  9. 9Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
  10. 10Center for Astrophysics ∣ Harvard & Smithsonian, Cambridge, MA, USA
  11. 11Department of Astronomy, University of Texas at Austin, Austin, TX, USA
  12. 12Department of Physics, University of Oxford, Oxford, UK
  13. 13Scuola Normale Superiore, Pisa, Italy
  14. 14Sorbonne Université, CNRS, Institut d'Astrophysique de Paris, Paris, France
  15. 15Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario, Canada
  16. 16Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands
  17. 17Steward Observatory, University of Arizona, Tucson, AZ, USA
  18. 18Institute of Astronomy, University of Cambridge, Cambridge, UK
  19. 19Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, China
  20. 20Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan
  21. 21Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield, UK
  22. 22St Catharine's College, University of Cambridge, Cambridge, UK
  23. 23Aix Marseille Université, CNRS, CNES, LAM (Laboratoire d'Astrophysique de Marseille), Marseille, France
  24. 24Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Heidelberg, Germany
  25. 25Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA, USA
  26. 26Dipartimento di Fisica, 'Sapienza' Università di Roma, Rome, Italy
  27. 27Como Lake Center for Astrophysics, DiSAT, Università degli Studi dell'Insubria, Como, Italy
  28. 28INAF/Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy
  29. 29Cosmic Dawn Center (DAWN), Copenhagen, Denmark
  30. 30Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  31. 31Department of Physics, University of Texas at Austin, Austin, TX, USA
  32. 32Weinberg Institute for Theoretical Physics, Texas Center for Cosmology and Astroparticle Physics, University of Texas at Austin, Austin, TX, USA
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Abstract

Recent discoveries of faint active galactic nuclei (AGN) at the redshift frontier have revealed a plethora of broad Hα emitters with optically red continua, named little red dots (LRDs) 1 , which comprise 15–30% of the high-redshift broad-line AGN population 2 . Owing to their peculiar properties 3–6 , modelling LRDs with standard AGN scenarios has proven challenging. In particular, the validity of single-epoch virial mass estimates in determining the black-hole masses of LRDs has been called into question, with some models claiming that masses might be overestimated by up to two orders of magnitude 7–10 . Here we report a direct, dynamical black-hole mass measurement in a strongly lensed LRD at a redshift of 7.04. The combination of lensing with deep spectroscopic data reveals a rotation curve that is inconsistent with a nuclear star cluster, yet can be well explained by Keplerian rotation around a point mass of 50 million solar masses, consistent with virial black-hole mass estimates. The Keplerian rotation leaves little room for any stellar component in a host galaxy, as we conservatively infer M BH / M ⁎ > 2 (where M BH is the black-hole mass and M ⁎ is the stellar mass). Such a ‘naked’ black hole, together with its near-pristine environment 11 , indicates that this LRD is a massive black-hole seed caught in its earliest accretion phase.

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Cite

BibTeXRIS
BibTeX
@article{juodzbalis2026direct,
  title = {{A direct black-hole mass measurement in a little red dot at high redshift}},
  author = {Ignas Juodžbalis and C. Marconcini and Francesco D’Eugenio and R. Maiolino and ALESSANDRO MARCONI and Hannah Übler and Jan Scholtz and Xihan Ji and Gareth C. Jones and Michele Perna and Santiago Arribas and Jake S. Bennett and Volker Bromm and Andrew J. Bunker and Stefano Carniani and S. Charlot and G. Cresci and Pratika Dayal and Eiichi Egami and A. C. Fabian and Kohei Inayoshi and Yuki Isobe and Lucy R. Ivey and Sophie Koudmani and Nicolas Laporte and Jianwei Lyu and Jianwei Lyu and Giovanni Mazzolari and Stephanie Monty and Eleonora Parlanti and Pablo G. Pérez‐González and Brant E. Robertson and Raffaella Schneider and Debora Sijacki and Sandro Tacchella and Alessandro Trinca and Rosa Valiante and Marta Volonteri and Joris Witstok and Saiyang Zhang},
  journal = {Nature},
  year = {2026},
  month = may,
  doi = {10.1038/s41586-026-10579-4},
  eprint = {2508.21748},
  archivePrefix = {arXiv},
  url = {https://doi.org/10.1038/s41586-026-10579-4},
  note = {CC BY},
}
RIS
TY  - JOUR
TI  - A direct black-hole mass measurement in a little red dot at high redshift
AU  - Ignas Juodžbalis
AU  - C. Marconcini
AU  - Francesco D’Eugenio
AU  - R. Maiolino
AU  - ALESSANDRO MARCONI
AU  - Hannah Übler
AU  - Jan Scholtz
AU  - Xihan Ji
AU  - Gareth C. Jones
AU  - Michele Perna
AU  - Santiago Arribas
AU  - Jake S. Bennett
AU  - Volker Bromm
AU  - Andrew J. Bunker
AU  - Stefano Carniani
AU  - S. Charlot
AU  - G. Cresci
AU  - Pratika Dayal
AU  - Eiichi Egami
AU  - A. C. Fabian
AU  - Kohei Inayoshi
AU  - Yuki Isobe
AU  - Lucy R. Ivey
AU  - Sophie Koudmani
AU  - Nicolas Laporte
AU  - Jianwei Lyu
AU  - Jianwei Lyu
AU  - Giovanni Mazzolari
AU  - Stephanie Monty
AU  - Eleonora Parlanti
AU  - Pablo G. Pérez‐González
AU  - Brant E. Robertson
AU  - Raffaella Schneider
AU  - Debora Sijacki
AU  - Sandro Tacchella
AU  - Alessandro Trinca
AU  - Rosa Valiante
AU  - Marta Volonteri
AU  - Joris Witstok
AU  - Saiyang Zhang
PY  - 2026
DA  - 2026/05/27
JO  - Nature
DO  - 10.1038/s41586-026-10579-4
UR  - https://doi.org/10.1038/s41586-026-10579-4
AB  - Recent discoveries of faint active galactic nuclei (AGN) at the redshift frontier have revealed a plethora of broad Hα emitters with optically red continua, named little red dots (LRDs) 1 , which comprise 15–30% of the high-redshift broad-line AGN population 2 . Owing to their peculiar properties 3–6 , modelling LRDs with standard AGN scenarios has proven challenging. In particular, the validity of single-epoch virial mass estimates in determining the black-hole masses of LRDs has been called into question, with some models claiming that masses might be overestimated by up to two orders of magnitude 7–10 . Here we report a direct, dynamical black-hole mass measurement in a strongly lensed LRD at a redshift of 7.04. The combination of lensing with deep spectroscopic data reveals a rotation curve that is inconsistent with a nuclear star cluster, yet can be well explained by Keplerian rotation around a point mass of 50 million solar masses, consistent with virial black-hole mass estimates. The Keplerian rotation leaves little room for any stellar component in a host galaxy, as we conservatively infer M BH / M ⁎ > 2 (where M BH is the black-hole mass and M ⁎ is the stellar mass). Such a ‘naked’ black hole, together with its near-pristine environment 11 , indicates that this LRD is a massive black-hole seed caught in its earliest accretion phase.
SN  - 0028-0836
SN  - 1476-4687
ER  -