GA-NIFS and EIGER: A merging quasar host at <i>z</i> = 7 with an overmassive black hole
The James Webb Space Telescope is revolutionising our ability to understand the host galaxies and local environments of high- z quasars. Here we obtain a comprehensive understanding of the host galaxy of the z = 7.08 quasar J1120+0641 by combining NIRSpec integral field spectroscopy with NIRCam photometry of the host continuum emission. Our emission-line maps reveal that this quasar host is undergoing a merger with a bright companion galaxy. The quasar host and the companion have similar dynamical masses of ∼10 10 M ⊙ , suggesting that this is a major galaxy interaction. Through detailed quasar subtraction and SED fitting using the NIRCam data, we obtained an estimate of the host stellar mass of M * = (3.0 −1.4 +2.5 ) × 10 9 M ⊙ , with M ∗ = (2.7 −0.5 +0.5 ) × 10 9 M ⊙ for the companion galaxy. Using the H β Balmer line, we estimated a virial black hole mass of M BH = (1.9 −1.1 +2.9 ) × 10 9 M ⊙ . Thus, J1120+0641 has an extreme black hole–stellar mass ratio of M BH / M * = 0.63 −0.31 +0.54 , which is ∼3 dex larger than expected by the local scaling relations between black hole and stellar mass. J1120+0641 is powered by an overmassive black hole with the highest reported black hole–stellar mass ratio in a quasar host that is currently undergoing a major merger. These new insights highlight the power of JWST for measuring and understanding these extreme first quasars.
Authors
- G. Cresci (ORCID: https://orcid.org/0000-0002-5281-1417)
- Francesco D’Eugenio (ORCID: https://orcid.org/0000-0003-2388-8172)
- Santiago Arribas (ORCID: https://orcid.org/0000-0001-7997-1640)
- Bruno Rodríguez Del Pino (ORCID: https://orcid.org/0000-0001-5171-3930)
- Michele Perna (ORCID: https://orcid.org/0000-0002-0362-5941)
- Jorryt Matthee (ORCID: https://orcid.org/0000-0003-2871-127X)
- R. Maiolino (ORCID: https://orcid.org/0000-0002-4985-3819)
- Ruari Mackenzie (ORCID: https://orcid.org/0000-0003-0417-385X)
- Chiara Circosta (ORCID: https://orcid.org/0000-0001-8522-9434)
- Stefano Carniani (ORCID: https://orcid.org/0000-0002-6719-380X)
- Rohan P. Naidu (ORCID: https://orcid.org/0000-0003-3997-5705)
- Madeline A. Marshall (ORCID: https://orcid.org/0000-0001-6434-7845)
- Chris J. Willott (ORCID: https://orcid.org/0000-0002-4201-7367)
- Gareth C. Jones (ORCID: https://orcid.org/0000-0002-0267-9024)
- S. Charlot (ORCID: https://orcid.org/0000-0003-3458-2275)
- Anna–Christina Eilers (ORCID: https://orcid.org/0000-0003-2895-6218)
- Hannah Übler (ORCID: https://orcid.org/0000-0003-4891-0794)
- Minghao Yue (ORCID: https://orcid.org/0000-0002-5367-8021)
- Jan Scholtz (ORCID: https://orcid.org/0000-0001-6010-6809)
- Rongmon Bordoloi (ORCID: https://orcid.org/0000-0002-3120-7173)
- Andrew J. Bunker (ORCID: https://orcid.org/0000-0002-8651-9879)
- Daichi Kashino (ORCID: https://orcid.org/0000-0001-9044-1747)
- Robert A. Simcoe (ORCID: https://orcid.org/0000-0003-3769-9559)
- Giacomo Venturi (ORCID: https://orcid.org/0000-0001-8349-3055)
- Torsten Böker
Publication Details
- Journal
- Astronomy and Astrophysics
- Published
- 2025-08-14
- DOI
- https://doi.org/10.1051/0004-6361/202452650
- Citations
- 14
- Primary Topic
- Astrophysical Phenomena and Observations
- Type
- article
- Field-Weighted Citation Impact
- 16.17
Funders
- Smithsonian Institution
- National Aeronautics and Space Administration
- Space Telescope Science Institute
- UK Research and Innovation
- European Commission
- Nuclear Safety and Security Commission
- Ministerio de Ciencia e Innovación
- Smithsonian Astrophysical Observatory
- Science and Technology Facilities Council
- European Research Council
- Japan Society for the Promotion of Science
- Agencia Estatal de Investigación
- Laboratory Directed Research and Development
- Los Alamos National Laboratory