A geometric distance to the supermassive black Hole of NGC 3783

¹ Max Planck Institute for Extraterrestrial Physics (MPE), Giessenbachstr.1, 85748 Garching, Germany
e-mail: shangguan@mpe.mpg.de
² LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
³ I. Institute of Physics, University of Cologne, Zülpicher Straße 77, 50937 Cologne, Germany
⁴ Departments of Physics and Astronomy, Le Conte Hall, University of California, Berkeley, CA 94720, USA
⁵ Department of Physics and Astronomy, University of Southampton, Southampton, UK
⁶ Department of Physics, Kyoto Sangyo University, Kita-ku, Japan
⁷ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France
⁸ School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
⁹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹⁰ Center for Computational Astrophysics, Flatiron Institute, 162 5th Ave., New York, NY 10010, USA
¹¹ European Southern Observatory, Casilla, 19001 Santiago 19, Chile
¹² European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
¹³ Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
¹⁴ Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121 Bonn, Germany
¹⁵ Universidade de Lisboa – Faculdade de Ciências, Campo Grande, 1749-016 Lisboa, Portugal
¹⁶ Faculdade de Engenharia, Universidade do Porto, rua Dr. Roberto Frias, 4200-465 Porto, Portugal
¹⁷ CENTRA – Centro de Astrofísica e Gravitação, IST, Universidade de Lisboa, 1049-001 Lisboa, Portugal
¹⁸ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
¹⁹ Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
²⁰ Department of Astrophysical & Planetary Sciences, JILA, University of Colorado, Duane Physics Bldg., 2000 Colorado Ave, Boulder, CO 80309, USA
²¹ Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia
²² Department of Physics, Technical University Munich, James-Franck-Straße 1, 85748 Garching, Germany
²³ Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
²⁴ LCOGT, 6740 Cortona Drive, Suite 102, Goleta, CA 93117, USA

Received: 29 May 2021
Accepted: 24 July 2021

Abstract

The angular size of the broad line region (BLR) of the nearby active galactic nucleus NGC 3783 has been spatially resolved by recent observations with VLTI/GRAVITY. A reverberation mapping (RM) campaign has also recently obtained high quality light curves and measured the linear size of the BLR in a way that is complementary to the GRAVITY measurement. The size and kinematics of the BLR can be better constrained by a joint analysis that combines both GRAVITY and RM data. This, in turn, allows us to obtain the mass of the supermassive black hole in NGC 3783 with an accuracy that is about a factor of two better than that inferred from GRAVITY data alone. We derive M_BH = 2.54_−0.72^+0.90 × 10⁷ M_⊙. Finally, and perhaps most notably, we are able to measure a geometric distance to NGC 3783 of 39.9_−11.9^+14.5 Mpc. We are able to test the robustness of the BLR-based geometric distance with measurements based on the Tully–Fisher relation and other indirect methods. We find the geometric distance is consistent with other methods within their scatter. We explore the potential of BLR-based geometric distances to directly constrain the Hubble constant, H₀, and identify differential phase uncertainties as the current dominant limitation to the H₀ measurement precision for individual sources.