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

Journal article

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 population2. Owing to their peculiar properties3, 4, 5–6, 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 magnitude7, 8, 9–10. 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 MBH/M⁎ > 2 (where MBH is the black-hole mass and M⁎ is the stellar mass). Such a ‘naked’ black hole, together with its near-pristine environment11, indicates that this LRD is a massive black-hole seed caught in its earliest accretion phase.

Authors: Juodžbalis, I; Marconcini, C; D’Eugenio, F; Maiolino, R; Marconi, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature
• Volume: 653
• Issue: 8116
• Pages: 1017-1021
• Publication date: 2026-05-27
• Acceptance date: 2026-04-21
• DOI: 10.1038/s41586-026-10579-4
• EISSN: 1476-4687
• ISSN: 0028-0836
• Language: English
• Keywords: Redshift; Virial mass; Solar mass; Virial theorem; Stellar mass; Population; Low Mass; Stars