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The accelerations of stars orbiting the Milky Way's central black hole

Abstract

Recent measurements1,2,3,4 of the velocities of stars near the centre of the Milky Way have provided the strongest evidence for the presence of a supermassive black hole in a galaxy5, but the observational uncertainties poorly constrain many of the black hole's properties. Determining the accelerations of stars in their orbits around the centre provides much more precise information about the position and mass of the black hole. Here we report measurements of the accelerations of three stars located 0.005 pc (projected on the sky) from the central radio source Sagittarius A* (Sgr A*); these accelerations are comparable to those experienced by the Earth as it orbits the Sun. These data increase the inferred minimum mass density in the central region of the Galaxy by an order of magnitude relative to previous results, and localize the dark mass to within 0.05 ± 0.04 arcsec of the nominal position of Sgr A*. In addition, the orbital period of one of the observed stars could be as short as 15 years, allowing us the opportunity in the near future to observe an entire period.

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Figure 1: East–west and north–south positional offsets from the nominal location of Sgr A* versus time for (a) S0-1, (b) S0-2, and (c) S0-4.
Figure 2: The acceleration uncertainty cones and their intersections.
Figure 3: The minimum enclosed mass implied by each star's acceleration measurement versus projected distance from the newly determined dynamical centre position.
Figure 4: The measured motion of S0-1, S0-2 and S0-4 and several allowed orbital solutions.

References

  1. 1

    Eckart, A. & Genzel, R. Stellar proper motions in the central 0.1 pc of the Galaxy. Mon. Not. R. Astron. Soc. 284, 576–598 (1997).

    ADS  Article  Google Scholar 

  2. 2

    Genzel, R., Eckart, A., Ott, T. & Eisenhauer, F. On the nature of the dark mass in the centre of the Milky Way. Mon. Not. R. Astron. Soc. 291–234, 219 (1997 ).

    ADS  Article  Google Scholar 

  3. 3

    Genzel, R., Pichon, C., Eckart, A., Gerhard, O. E. & Ott, T. Stellar dynamics in the galactic centre: Proper motions and anisotropy. Mon. Not. R. Astron. Soc. (in the press).

  4. 4

    Ghez, A. M., Klein, B. L., Morris, M. & Becklin, E. E. High proper-motion stars in the vicinity of Sagittarius A*: Evidence for a supermassive black hole at the center of our galaxy. Astrophys. J. 509 , 678–686 (1998).

    ADS  Article  Google Scholar 

  5. 5

    Maoz, E. Dynamical constraints on alternatives to supermassive black holes in galactic nuclei. Astrophys. J. 494, L181– L184 (1998).

    ADS  Article  Google Scholar 

  6. 6

    Reid, M. J. The distance to the center of the Galaxy. Annu. Rev. Astron. Astrophys. 31, 345–372 ( 1993).

    ADS  CAS  Article  Google Scholar 

  7. 7

    Matthews, K. & Soifer, B. T. in Astronomy with Infrared Arrays: The Next Generation (ed. McLean, I.) Vol. 190, 239– 246 (Astrophysics and Space Sciences Library, Kluwer Academic, Dordrecht, 1994).

    Book  Google Scholar 

  8. 8

    Matthews, K., Ghez, A. M., Weinberger, A. J. & Neugebauer, G. The diffraction-limited images from the W. M. Keck Telescope. Proc. Astron. Soc. Pacif. 108, 615– 619 (1996).

    ADS  Article  Google Scholar 

  9. 9

    Menten, K. M., Reid, M. J., Eckart, A. & Genzel, R. The position of Sgr A*: Accurate alignment of the radio and infrared reference frames at the galactic center. Astrophys. J. 475, L111 –L114 (1997).

    ADS  CAS  Article  Google Scholar 

  10. 10

    Lo, K. Y., Shen, Z.-Q., Zhao, J.-H. & Ho, P. T. Intrinsic size of SGR A*: 72 Schwarzschild radii. Astrophys. J. 508, L61–L64 (1998).

    ADS  Article  Google Scholar 

  11. 11

    Reid, M. J., Readhead, A. C. S., Vermeulen, R. C. & Treuhaft, R. N. The proper motion of Sagittarius A*. I. First VLBA results. Astrophys. J. 524, 816–823 ( 1999).

    ADS  Article  Google Scholar 

  12. 12

    Backer, D. C. & Sramek, R. A. Proper motion of the compact, nonthermal radio source in the galactic center, Sagittarius A*. Astrophys. J. 524, 805–815 (1999).

    ADS  Article  Google Scholar 

  13. 13

    Salati, P. & Silk, J. A stellar probe of dark matter annihilation in galactic nuclei. Astrophys. J. 338, 24 –31 (1989).

    ADS  CAS  Article  Google Scholar 

  14. 14

    Tsiklauri, D. & Viollier, R. D. Dark matter concentration in the galactic center. Astrophys. J. 500, 591–595 (1998).

    ADS  CAS  Article  Google Scholar 

  15. 15

    Gondolo, P. & Silk, J. Dark matter annihilation at the galactic center. Phys. Rev. Lett. 83, 1719– 1722 (1999).

    ADS  CAS  Article  Google Scholar 

  16. 16

    Torres, D. F., Capozziello, S. & Lambiase, G. A supermassive boson star at the galactic center? Astrophys. J. (in the press).

  17. 17

    Romanowsky, A. & Kochanek, C. in Proceedings of Dynamics of Star Clusters and the Milky Way (ASP Conference Series, Astronomical Society of the Pacific, San Francisco, in the press).

  18. 18

    Sanders, R. H. The case against a massive black hole at the Galactic Centre. Nature 359, 131–132 ( 1992).

    ADS  Article  Google Scholar 

  19. 19

    Morris, M., Ghez, A. M. & Becklin, E. E. The galactic center black hole: clues for the evolution of black holes in galactic nuclei. Adv. Space Res. 23, 959–968 (1999).

    ADS  CAS  Article  Google Scholar 

  20. 20

    Gerhard, O. The galactic center He I stars: remains of a dissolved young cluster? Astrophys. J. (submitted).

  21. 21

    Salim, S. & Gould, A. Sagittarius A* “Visual Binaries”: A direct measurement of the galactocentric distance. Astrophys. J. 523, 633–641 ( 1999).

    ADS  Article  Google Scholar 

  22. 22

    Babu, G. J. & Feigelson, E. D. Astrostatistics (Chapman & Hall, London, 1996).

    Book  Google Scholar 

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Acknowledgements

This work was supported by the National Science Foundation and the Packard Foundation. We are grateful to J. Larkin for exchanging telescope time; O. Gerhard, M. Jura, and A. Weinberger for useful input; telescope observing assistants J. Aycock, T. Chelminiak, G. Puniwai, C. Sorenson, W. Wack, M. Whittle and software/instrument specialists A. Conrad and B. Goodrich for their help during the observations. The data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the financial support of the W. M. Keck Foundation.

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Correspondence to A. M. Ghez.

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Ghez, A., Morris, M., Becklin, E. et al. The accelerations of stars orbiting the Milky Way's central black hole . Nature 407, 349–351 (2000). https://doi.org/10.1038/35030032

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