1. Mass distribution in the Galactic Center based on interferometric astrometry of multiple stellar orbits
- Author
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Abuter, R., Aimar, N., Amorim, A., Ball, J., Bauböck, M., Berger, J.P., Bonnet, H., Bourdarot, G., Brandner, W., Cardoso, V., Clénet, Y., Dallilar, Y., Davies, R., de Zeeuw, P.T., Dexter, J., Drescher, A., Eisenhauer, F., Schreiber, N.M. Förster, Foschi, A., Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Habibi, M., Haubois, X., Heißel, G., Henning, T., Hippler, S., Horrobin, M., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Lacour, S., Lapeyrère, V., Le Bouquin, J.-B., Léna, P., Lutz, D., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Shangguan, J., Shimizu, T., Scheithauer, S., Stadler, J., Stephens, A.W., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L.J., Tristram, K.R. W., Vincent, F., von Fellenberg, S., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Young, A.
- Subjects
Astrophysics - instrumentation and methods for astrophysics ,Astrophysics and Astronomy ,General Relativity and Cosmology ,Astrophysics::High Energy Astrophysical Phenomena ,gr-qc ,astro-ph.GA ,Astrophysics - astrophysics of galaxies ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Black hole physics ,Instrumentation - interferometers ,Space and Planetary Science ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,General relativity and quantum cosmology ,Astrophysics::Galaxy Astrophysics ,Galaxy - center ,astro-ph.IM - Abstract
Stars orbiting the compact radio source Sgr A* in the Galactic Center serve as precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics-assisted astrometry (with NACO/VLT) and spectroscopy (with SINFONI/VLT, NIRC2/Keck and GNIRS/Gemini) over three decades, we have obtained 30–100 μas astrometry since 2017 with the four-telescope interferometric beam combiner GRAVITY/VLTI, capable of reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry in the field. The new data for the stars S2, S29, S38, and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M• = 4.30 × 106 M⊙, with a precision of about ±0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7σ. Assuming plausible density profiles, the extended mass component inside the S2 apocenter (≈0.23″ or 2.4 × 104 RS) must be ≲3000 M⊙ (1σ), or ≲0.1% of M•. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* is tentatively seen is r ≈ 2.5″ ≥ 10× the apocenter of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.Key words: black hole physics / instrumentation: interferometers / Galaxy: center⋆ GRAVITY is developed in a collaboration by MPE, LESIA of Paris Observatory/CNRS/Sorbonne Université/Univ. Paris Diderot and IPAG of Université Grenoble Alpes/CNRS, MPIA, Univ. of Cologne, CENTRA – Centro de Astrofisica e Gravitação, and ESO.⋆⋆ Corresponding authors: S. Gillessen (e-mail: ste@mpe.mpg.de), F. Widmann (e-mail: fwidmann@mpe.mpg.de), and G. Heißel (e-mail: gernot.heissel@obspm.fr). The stars orbiting the compact radio source Sgr A* in the Galactic Centre are precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy (with SINFONI / VLT, NIRC2 / Keck and GNIRS / Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as astrometry with the four-telescope interferometric beam combiner GRAVITY / VLTI reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry. The new data for the stars S2, S29, S38 and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M = 4.30 x 10^6 M_sun with a precision of about +-0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7 sigma. Assuming plausible density profiles, an extended mass component inside S2's apocentre (= 0.23" or 2.4 x 10^4 R_S) must be 3000 M_sun (1 sigma), or 0.1% of M. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* tentatively is seen is r = 2.5" >= 10x the apocentre of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.
- Published
- 2022