AAS 204th Meeting, June 2004
Session 17 Galaxies Including Our Own
Oral, Monday, May 31, 2004, 10:00-11:30am, 710/712

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[17.02] Stellar Dynamics at the Galactic Center with a Thirty Meter Telescope

N. N. Weinberg, M. Milosavljevic (Caltech)

We discuss physical experiments achievable via the infrared monitoring of stellar dynamics in the neighborhood of the massive black hole at the Galactic center with the proposed Thirty Meter Telescope (TMT). Given the likely observational capabilities of the TMT and present knowledge of the stellar environment at the Galactic Center, we construct plausible samples of stellar orbits around the black hole. Using the Markov Chain Monte Carlo method we evaluate the constraints such orbits place on the matter content within the dynamical sphere of influence of the black hole. We find that if the extended matter distribution enclosed by the orbits has a density greater than ~108 M\odot pc-3 it will produce measurable non-Keplerian effects. Thus, if the dark matter cusp at the Galactic Center matches the profiles expected in standard models of dark matter clustering, its influence will be detectable with the TMT. We also evaluate the constraint on the mass of the black hole, and the distance to the Galactic Center, and find that both can be measured to better than ~0.1%. We discuss the significance of measuring the distance to within a few parsecs and the implications of the measurement for understanding the structure of the Galaxy. We demonstrate that relativistic effects, such as the prograde orbital precession, are also detectable with the TMT, though higher-order effects such as black hole spin-induced precession are not. Finally, we calculate the rate at which monitored stars undergo two-body encounters with background stars, resulting in detectable changes in orbital motions. Such encounters serve as a probe of the mass function of the background stars. We find that several such encounters are expected to be detected with the TMT over a ten year period.

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