Volume 625, May 2019
|Number of page(s)||10|
|Section||Letters to the Editor|
|Published online||20 May 2019|
Letter to the Editor
A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty⋆
Max Planck Institute for Extraterrestrial Physics (MPE), Giessenbachstr. 1, 85748 Garching, Germany
2 LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 92195 Meudon Cedex, France
3 Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
4 1. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
5 Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
6 CENTRA and Universidade de Lisboa – Faculdade de Ciências, Campo Grande, 1749-016 Lisboa, Portugal
7 CENTRA and Universidade do Porto – Faculdade de Engenharia, 4200-465 Porto, Portugal
8 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
9 European Southern Observatory, Casilla, 19001 Santiago 19, Chile
10 Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
11 Departments of Physics and Astronomy, Le Conte Hall, University of California, Berkeley, CA 94720, USA
12 School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
13 Max-Planck-Institute for Radio Astronomy, Auf dem Hügel 69, 53121 Bonn, Germany
14 Center for Computational Astrophysics, Flatiron Institute, 162 5th Ave., New York, NY 10010, USA
Accepted: 25 April 2019
We present a 0.16% precise and 0.27% accurate determination of R0, the distance to the Galactic center. Our measurement uses the star S2 on its 16-year orbit around the massive black hole Sgr A* that we followed astrometrically and spectroscopically for 27 years. Since 2017, we added near-infrared interferometry with the VLTI beam combiner GRAVITY, yielding a direct measurement of the separation vector between S2 and Sgr A* with an accuracy as good as 20 μas in the best cases. S2 passed the pericenter of its highly eccentric orbit in May 2018, and we followed the passage with dense sampling throughout the year. Together with our spectroscopy, in the best cases with an error of 7 km s−1, this yields a geometric distance estimate of R0 = 8178 ± 13stat. ± 22sys. pc. This work updates our previous publication, in which we reported the first detection of the gravitational redshift in the S2 data. The redshift term is now detected with a significance level of 20σ with fredshift = 1.04 ± 0.05.
Key words: black hole physics / astrometry / Galaxy: nucleus
GRAVITY has been developed by a collaboration of the Max Planck Institute for Extraterrestrial Physics, LESIA of Paris Observatory/CNRS/UPMC/Univ. Paris Diderot and IPAG of Université Grenoble Alpes/CNRS, the Max Planck Institute for Astronomy, the University of Cologne, the Centro de Astrofísica e Gravitaçâo, and the European Southern Observatory.
© R. Abuter et al. 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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