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| Paper: |
Dynamical Evidence for a Supermassive Black Hole at the Center of the Milky Way |
| Volume: |
182, Galaxy Dynamics: A Rutgers Symposium |
| Page: |
24 |
| Authors: |
Ghez, A. M.; Morris, M.; Becklin, E. E. |
| Abstract: |
While the presence of a supermassive black hole at the center of our Galaxy has long been suspected, and while the available dynamical evidence has long been consistent with that suspicion, the data have only recently become unambiguous and compelling that alternative hypotheses are not feasible. The most dramatic evidence has been provided by measurements of the proper motions of stars in the central stellar cluster, using diffraction-limited imaging with large telescopes. Stars moving at velocities up to 1400 km s^{-1} have been measured at projected distances from Sgr A^*, the apparent radio counterpart of the black hole, down to 0.004 pc (0.1^''). Comparison of proper motions with measured radial velocities at radio ~0.1pc suggests that the stellar motions are isotropically distributed. This is consistent with the fact that several mass estimators give approximately the same result for the central mass, 2.6 +/- 0.2 × 10^6 Msun, in spite of differing dependences on the isotropy of the orbits. In addition, the velocity dispersion measured as a function of radius is extremely well fitted by Keplerian motion around a point mass of this magnitude. Alternatives to a single, supermassive black hole are examined, and deemed inviable. |
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