• DOI:10.1051/0004-6361/202037813
• Corpus ID: 215768928

Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

@article{Abuter2020DetectionOT,
  title={Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole},
  author={Roberto N. Abuter and Ant{\'o}nio Amorim and Michi Baub{\"o}ck and J. P. Berger and Henri Bonnet and Wolfgang Brandner and V{\'i}tor Cardoso and Yann Cl{\'e}net and P. Tim de Zeeuw and Jason Dexter and Andreas Eckart and Frank Eisenhauer and Natascha M. F{\"o}rster Schreiber and P. Garcia and Feng Gao and Eric Gendron and Reinhard Genzel and Stefan Gillessen and Maryam Habibi and Xavier Haubois and Th. Henning and Stephen Hippler and M. Horrobin and Alejandra Jim{\'e}nez-Rosales and L. Jochum and L. Jocou and A. Kaufer and Pierre Kervella and Sylvestre Lacour and Vincent Lapeyr{\`e}re and Jean-Baptiste Le Bouquin and P. L{\'e}na and M. Nowak and Thomas Ott and T. Paumard and K. Perraut and Guy Perrin and Oliver Pfuhl and G. Rodr{\'i}guez-Coira and Jinyi Shangguan and Silvia Scheithauer and J. Stadler and Odele Straub and C. Straubmeier and Eckhard Sturm and Linda J. Tacconi and Frederic H. Vincent and Sebastiano D. von Fellenberg and Idel Waisberg and Felix Widmann and Ekkehard Wieprecht and Erich Wiezorrek and Julien Woillez and S. Yazici and G{\'e}rard Zins},
  journal={Astronomy \& Astrophysics},
  year={2020}
}

• R. Abuter, A. Amorim, +52 authors G. Zins
• Published 1 April 2020
• Physics
• Astronomy & Astrophysics

The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star’s radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this Letter we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2’s orbit. Owing to its highly elliptical orbit (e = 0.88), S2’s SP is mainly a kink between the pre-and post-pericentre directions of motion ≈±1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017−2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2’s position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states (“flares”) of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter fSP for the SP (fSP = 0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, δϕ ≈ 12′ per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find fSP = 1.10 ± 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2’s orbit cannot exceed ≈0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M⊙.