EDP Sciences : Mass distribution in the Galactic Center based on interferometric astrometry of multiple stellar orbits

Abuter, R.; Lutz, D.; Stephens, A.W.; de Zeeuw, P.T.; Shimizu, T.; Sturm, E.; Wieprecht, E.; Perrin, G.; Kaufer, A.; Perraut, K.; Jocou, L.; Gillessen, S.; Bauböck, M.; Amorim, A.; Brandner, W.; Lapeyrère, V.; Stadler, J.; Hippler, S.; Le Bouquin, J.-B.; Clénet, Y.; Davies, R.; Henning, T.; Drescher, A.; Tristram, K.R. W.; Straub, O.; Heißel, G.; Young, A.; Dexter, J.; Kervella, P.; Bourdarot, G.; Schreiber, N.M. Förster; von Fellenberg, S.; Lacour, S.; Tacconi, L.J.; Dallilar, Y.; Ball, J.; Foschi, A.; Straubmeier, C.; Léna, P.; Haubois, X.; Aimar, N.; Yazici, S.; Berger, J.P.; Habibi, M.; Shangguan, J.; Gao, F.; Genzel, R.; Paumard, T.; Jochum, L.; Scheithauer, S.; Eisenhauer, F.; Rabien, S.; Bonnet, H.; Garcia, P.; Cardoso, V.; Pfuhl, O.; Woillez, J.; Ott, T.; Wiezorrek, E.; Widmann, F.; Gendron, E.; Horrobin, M.; Vincent, F.

doi:10.1051/0004-6361/202142465

Article
Report number	arXiv:2112.07478
Title	Mass distribution in the Galactic Center based on interferometric astrometry of multiple stellar orbits
Author(s)	Abuter, R. (European Southern Observ.) ; Aimar, N. (LESIA, Meudon) ; Amorim, A. (Lisbon U. ; Lisbon, CENTRA) ; Ball, J. (Gemini Observ., Hilo) ; Bauböck, M. (Garching, Max Planck Inst. ; Illinois U., Urbana) ; Berger, J.P. (U. Grenoble Alpes ; European Southern Observ.) ; Bonnet, H. (European Southern Observ.) ; Bourdarot, G. (U. Grenoble Alpes ; Garching, Max Planck Inst.) ; Brandner, W. (Heidelberg, Max Planck Inst. Astron.) ; Cardoso, V. (Lisbon, CENTRA ; CERN) ; Clénet, Y. (LESIA, Meudon) ; Dallilar, Y. (Garching, Max Planck Inst.) ; Davies, R. (Garching, Max Planck Inst.) ; de Zeeuw, P.T. (Leiden Observ. ; Garching, Max Planck Inst.) ; Dexter, J. (JILA, Boulder) ; Drescher, A. (Garching, Max Planck Inst.) ; Eisenhauer, F. (Garching, Max Planck Inst.) ; Schreiber, N.M. Förster (Garching, Max Planck Inst.) ; Foschi, A. (Lisbon, CENTRA ; CERN) ; Garcia, P. (Rio Grande do Sul U., Porto Alegre (main)) ; Gao, F. (Hamburg Observ. ; Garching, Max Planck Inst.) ; Gendron, E. (LESIA, Meudon) ; Genzel, R. (Garching, Max Planck Inst. ; UC, Berkeley) ; Gillessen, S. (Garching, Max Planck Inst.) ; Habibi, M. (Garching, Max Planck Inst.) ; Haubois, X. (European Southern Obs., Chile) ; Heißel, G. (LESIA, Meudon) ; Henning, T. (Heidelberg, Max Planck Inst. Astron.) ; Hippler, S. (Heidelberg, Max Planck Inst. Astron.) ; Horrobin, M. (Cologne U.) ; Jochum, L. (European Southern Obs., Chile) ; Jocou, L. (U. Grenoble Alpes) ; Kaufer, A. (European Southern Obs., Chile) ; Kervella, P. (LESIA, Meudon) ; Lacour, S. (LESIA, Meudon) ; Lapeyrère, V. (LESIA, Meudon) ; Le Bouquin, J.-B. (U. Grenoble Alpes) ; Léna, P. (LESIA, Meudon) ; Lutz, D. (Garching, Max Planck Inst.) ; Ott, T. (Garching, Max Planck Inst.) ; Paumard, T. (LESIA, Meudon) ; Perraut, K. (U. Grenoble Alpes) ; Perrin, G. (LESIA, Meudon) ; Pfuhl, O. (European Southern Observ. ; Garching, Max Planck Inst.) ; Rabien, S. (Garching, Max Planck Inst.) ; Shangguan, J. (Garching, Max Planck Inst.) ; Shimizu, T. (Garching, Max Planck Inst.) ; Scheithauer, S. (Heidelberg, Max Planck Inst. Astron.) ; Stadler, J. (Garching, Max Planck Inst.) ; Stephens, A.W. (Gemini Observ., Hilo) ; Straub, O. (Garching, Max Planck Inst.) ; Straubmeier, C. (Cologne U.) ; Sturm, E. (Garching, Max Planck Inst.) ; Tacconi, L.J. (Garching, Max Planck Inst.) ; Tristram, K.R. W. (European Southern Observ.) ; Vincent, F. (LESIA, Meudon) ; von Fellenberg, S. (Garching, Max Planck Inst.) ; Widmann, F. (Garching, Max Planck Inst.) ; Wieprecht, E. (Garching, Max Planck Inst.) ; Wiezorrek, E. (Garching, Max Planck Inst.) ; Woillez, J. (European Southern Observ.) ; Yazici, S. (Garching, Max Planck Inst. ; Cologne U.) ; Young, A. (Garching, Max Planck Inst.)
Publication	2022-01-01
Imprint	2021-12-14
Number of pages	17
In:	Astron. Astrophys. 657 (2022) L12
DOI	10.1051/0004-6361/202142465 (publication)
Subject category	gr-qc ; General Relativity and Cosmology ; astro-ph.IM ; Astrophysics and Astronomy ; astro-ph.GA ; Astrophysics and Astronomy
Accelerator/Facility, Experiment	GRAVITY
Abstract	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.
Copyright/License	publication: © 2022-2024 GRAVITY Collaboration (License: CC-BY-4.0) preprint: (License: CC BY 4.0)

$Progress in stellar astrometric imaging in the GC, from seeing limited observations ($\approx 0.4-0.5''$ FWHM, top left) to AO imaging on $8-10\,$m class telescopes ($50-60\,$mas FWHM, $\approx 300-500\,\mu$as astrometry (top-right), showing a Lucy-Richardson deconvolved and beam-restored AO image), to current interferometric imagery with GRAVITY / VLTI (bottom panels, $2\times4$ mas FWHM resolution, $30-100\,\mu$as astrometry). Bottom right: Central $0.2''$ region centered on Sgr~A*(IR) on May 30, 2021 (see Appendix~\ref{sec:A2}, \citealt{JULIA}). Over 2021, the central GRAVITY field of view was dominated by four stars (S29, S55, S62, and S300) with K-band magnitudes between 16.7 and 19.2, in addition to variable emission from Sgr~A*(IR) itself. The dashed circle indicates the field-of-view of GRAVITY, defined by the Gaussian acceptance profile of the pick-up fibres in the instrument. Comparing in the bottom left panel three such images taken on March 30 (red), May 30 (green), and July 26 (blue), the orbital motions of all four stars are easily seen, topped by the $\approx8740\,$km/s velocity of S29 at its pericenter on 2021.41 ($R_\mathrm{peri} \approx 100\,$AU).$

$Illustration of the fit results for $f_\mathrm{SP}$. We show the key figures for S2. The two left panels show the residuals in RA (top) and Dec (bottom) between the GRAVITY (cyan filled circles, and $1\sigma$ uncertainties) and NACO data (blue filled circles) and the best GR fit (red curve, $f_\mathrm{SP}=1$, R{\o}mer effect, plus special relativity, plus gravitational redshift and Schwarzschild precession), relative to the same orbit for $f_\mathrm{SP}=0$ (Kepler/Newton, plus R{\o}mer effect, plus special relativity, plus redshift). The orbital elements for non-Keplerian orbits (i.e., with $f_\mathrm{SP} \ne 0$) are interpreted as osculating parameters at apocenter time, 2010.35. NACO and GRAVITY data are averages of several epochs. The grey bars denote averages over all NACO data near apocenter (2004-2013). Top right: the same for the residual orbital angle on the sky $\delta \phi =\phi(f_\mathrm{SP}=1)-\phi(f_\mathrm{SP}=0)$. Bottom right: Zoom into the 2005/2021 part of the orbit, plotted in the mass rest frame. The earlier orbital trace does not coincide with the current one due to the Schwarzschild precession.$ Show more plots

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Записът е създаден на 2022-04-07, последна промяна на 2023-12-14

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