The gas physics and dynamics in the central 30 pc of the Galactic Center

B. Vollmer1, W.J. Duschl2, R. Zylka3

1 Max-Planck-Institut für Radioastronomie, Bonn, Germany
2 ITA,Universität Heidelberg, Germany
3 Universität Köln, Germany


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see: A&A, 367, 72 (2001); A&A, 377, 1016 (2001); A&A, 388, 128 (2002)

We have investigated the gas physics and dynamics of the Circumnuclear Disk and the surrounding GMCs in the Galactic Center. An analytic model for a clumped gas and dust disk will be presented where the gas clumps are described as isothermal spheres partially ionized by the external UV radiation field. The disk structure formed by the clouds is described as a quasi standard continuous accretion disk using adequately averaged parameters of the discrete cloud model. It is shown that the resulting physical characteristics of the clouds and the disk are in good agreement with all comparable observations at multiple wavelengths. The influence of rotation and magnetic fields on the physical properties of isothermal gas clouds will be discussed and a mechanism responsible for the formation of the inner edge of the Circumnuclear Disk will be suggested. In a second step we investigated the interaction of a pre-existing CND with a GMC. Retrograde and prograde encounters of a cloud of several 104 M falling onto an already existing nuclear disk using different energy loss rates per collision were simulated. The influence of the energy loss rate per collision on the evolution of the mass accretion and cloud collision rates will be shown. These simulations will be directly compared to the observed gas morphology and velocity field. In a last step we use absorption features in NIR (2MASS data) to reconstruct the LOS distribution of the gas in the inner 30 pc of the Galaxy.