Spatially resolved broad-line region in a quasar at <i>z</i> = 4
K. El Dayem, N. Aimar, Anthony Berdeu, J.-P. Berger, G. Bourdarot, P. Bourget, W. Brandner, Yixian Cao, C. Correia, Salvador Cuevas Cardona, R. Davies, D. Defrère, A. Drescher, A. Eckart, F. Eisenhauer, Maximilian Fabricius, Alejandro Farah, H. Feuchtgruber, N. M. Förster Schreiber, A. Foschi, P. García, R. García López, R. Genzel, S. Gillessen, Tiago Gomes, Frédéric Gonté, V. Gopinath, J. Graf, Michael Hartl, X. Haubois, F. Haußmann, L. C. Ho, S. F. Hönig, M. Houllé, Simran Joharle, Carolina Keiman, P. Kervella, J. Kolb, Laura Kreidberg, A. Labdon, S. Lacour, Olivier Lai, Samuel Lai, R. Laugier, J.-B. Le Bouquin, J. Leftley, R. Li, B. Lopez, D. Lutz, F. Mang, A. Mérand, F. Millour, M. Montargès, Nikhil More, Nuno Morujão, H. Nowacki, M. Nowak, Sylvain Oberti, Christopher A. Onken, J. Osorno, T. Ott, T. Paumard, K. Perraut, G. Perrin, R. Petrov, P.-O. Petrucci, N. Pourré, S. Rabien, Christian Rau, D. Ribeiro, S. Robbe-Dubois, M. Sadun Bordoni, Muhammad Salman, J. Sánchez-Bermúdez, D. Santos, J. Sauter, M. Scialpi, J. Scigliuto, J. Shangguan, Pavel Shchekaturov, Thomas Shimizu, Ferréol Soulez, C. Straubmeier, E. Sturm, M. Subroweit, C. Sykes, L. J. Tacconi, H. Übler, Gerhard Ulbricht, F. Vincent, R. Webster, E. Wieprecht, J. Woillez, C. Wolf
Abstract
We present the first near-infrared interferometric data of a QSO at z = 4. The K -band observations were performed with GRAVITY+ on the VLTI using all four UTs, detecting a differential phase signal that traces the spatially resolved kinematics for both the H β and H γ lines in the broad-line region (BLR). We fit the two lines simultaneously with an updated model that includes distinct rotating and conical outflowing components. For the best-fit model, more than 80% of the H I line emission from the BLR originates in an outflow with a velocity up to 10 4 km s −1 . This is oriented so that our line of sight is along an edge of the conical structure, which produces the prominent blue wing on the line profile. A combination of anisotropic line emission and mid-plane opacity leads to the single-sided phase signal. The model is able to qualitatively match both the outflowing C IV line profile and the systemic O I fluorescent emission. The black hole mass of 8 × 10 8 M ⊙ that we derive is the highest redshift black hole mass measurement to date obtained directly from BLR dynamics. It is an order of magnitude lower than that inferred from various single epoch scaling relations, and it implies that the accretion is highly super-Eddington. With reference to recent simulations, the data suggest that this QSO is emitting close to its radiative limit in a regime where strong outflows are expected around a polar conical region.