A dynamical measure of the black hole mass in a quasar 11 billion years ago.
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Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)1-3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase4-6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3)7. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-μas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 108 solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 1011 solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems.
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Acknowledgements: GRAVITY+ is developed by the Max Planck Institute for Extraterrestrial Physics, the Institute National des Sciences de l’Univers du CNRS (INSU) with its institutes LESIA/Paris Observatory-PSL, IPAG/Grenoble Observatory, Lagrange/Côte d’Azur Observatory and CRAL/Lyon Observatory, the Max Planck Institute for Astronomy, the University of Cologne, the CENTRA – Centro de Astrofisica e Gravitação, the University of Southampton, the Katholieke Universiteit Leuven and the European Southern Observatory. We are very grateful to our funding agencies (MPG, DFG, BMBF, ERC, CNRS (CSAA, ASHRA), Ile-de-France region (DIM ACAV+), Paris Observatory-PSL, Observatoire des Sciences de l’Univers de Grenoble, Université Grenoble Alpes, Observatoire de la Côte d’Azur, Université Côte d’Azur and the Fundação para a Ciência e Tecnologia) and the generous support from the Max Planck Foundation, an independent, non-profit organization of private supporters of top research in the Max Planck Society. We are also grateful to the European Southern Observatory and the Paranal staff and to the many scientific and technical staff members in our institutions, who helped to make GRAVITY and GRAVITY+ a reality. F.W. has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 101004719. D.D., M.Sa. and R.L. acknowledge the support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 866070). J.S.-B. acknowledges the support received from the UNAM PAPIIT project IA 105023 and from the CONAHCyT ‘Ciencia de Frontera’ project CF-2019/263975. A.A. and P.Ga. acknowledge support by Fundação para a Ciência e a Tecnologia (grants UIDB/00099/2020 and PTDC/FIS-AST/7002/2020). R.G.L. acknowledges support from Science Foundation Ireland (grant no. 18/SIRG/5597). The research leading to this work was supported by the French government through the ANR AGN_MELBa project (reference number ANR-21-CE31-0011) and by the European Union’s Horizon 2020 Research and Innovation programme under grant agreement no. 101004719 (OPTICON RadioNet Pilot).
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1476-4687
