The dynamics of the Circumnuclear Disk and its environment in the Galactic centre

Abstract

We address the question of the dynamics in the inner 50 pc of the Galactic Centre. In a first step we investigate the cloud-cloud collision rate in the Circumnuclear Disk (CND) with the help of a three dimensional N-body code using gas particles that can have inelastic collisions. The CND might be a longer lived structure than previously assumed. The whole disk-like structure of the CND can thus survive for several million years. A realistic simulation of the CND shows the observed disk height structure. In a second step the environment of the CND is taken into account. Retrograde and prograde encounters of a cloud of several 10^4 M_solar falling onto an already existing nuclear disk using different energy loss rates per collision are simulated. The influence of the energy loss rate per collision on the evolution of the mass accretion and cloud collision rates is strongest for a prograde encounter. A composite data cube of two different snapshots of a prograde encounter together with the CND shows striking similarity with the observed Sgr A cloud complex. The current appearance of the Galactic Centre environment can thus be explained by at least two dynamically distinct features together with the CND. The current mass accretion rate within the CND ranges between 10^-3 and 10^-4 M_solar yr^-1. It can rise up to several 10^-2 M_solar yr^-1 during massive accretion events.

14 pages with 22 figures. Accepted for publication in A&A

References in corpus (4)

• Molecular Tracers of the Central 12 pc of the Galactic Center
• Turbulent viscosity in clumpy accretion disks. Application to the Galaxy
• The stability of the Circumnuclear Disk clouds in the Galactic Centre
• A cloudy model for the Circumnuclear Disk in the Galactic Centre

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• Molecular Gas Feeding the Circumnuclear Disk of the Galactic Center
• Dense Ionized and Neutral Gas Surrounding Sgr A*
• The Inner 2 pc of Sagittarius A*: Simulations of the Circumnuclear Disk and Multiphase Gas Accretion in the Galactic Center
• The Galactic Center: A PeV Cosmic Ray Acceleration Factory
• Stability of Gas Clouds in Galactic Nuclei: An Extended Virial Theorem
• The Nuclear Filaments inside the Circumnuclear Disk in the Central 0.5 pc of the Galactic center
• A common origin for the circumnuclear disc and the nearby molecular clouds in the Galactic Centre
• Dark Matter as an active gravitational agent in cloud complexes
• Gas physics and dynamics in the central 50 pc of the Galaxy
• From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs -- Modelling the molecular emission of a parsec-scale torus as found in NGC1068