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Simple hydrodynamical Simulations of the Circumnuclear Disk

Coker, Robert F. and Christopher, Michol H. and Stolovy, Susan R. and Scoville, Nick Z. (2003) Simple hydrodynamical Simulations of the Circumnuclear Disk. Astronomische Nachrichten, 324 (S1). pp. 629-634. ISSN 0004-6337. doi:10.1002/asna.200385057.

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The “circumnuclear disk” (CND) is a dense, clumpy, asymmetric ring‐like feature centered on Sgr A*. The outer edge of the CND is not distinct but the disk extends for more than 7 pc; the distinct inner edge, at a radius of ≃1.5 pc, surrounds the “mini‐spiral” of the HII region, Sgr A West. We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars. A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. However, within a few parsecs of Sgr A*, the stellar winds decelerate any in‐falling cloud so that the wind‐cloud interface becomes Rayleigh‐Taylor unstable, potentially disrupting the cloud and inhibiting star formation.

Item Type:Article
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URLURL TypeDescription ItemConference Paper
Scoville, Nick Z.0000-0002-0438-3323
Additional Information:© 2003 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim. Issue Online: 20 October 2003; Version of Record online: 20 October 2003. This work was supported in part by UK PPARC and DOE. Some of the calculations reported here were carried out using UKAFF, a high-performance computing facility funded by UK PPARC.
Funding AgencyGrant Number
Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Subject Keywords:GMC; simulation; Sgr A
Issue or Number:S1
Record Number:CaltechAUTHORS:20180508-155748418
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Official Citation:Coker, R. F., Christopher, M. H., Stolovy, S. R. and Scoville, N. Z. (2003), Simple hydrodynamical Simulations of the Circumnuclear Disk. Astron. Nachr., 324: 629-634. doi:10.1002/asna.200385057
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86298
Deposited By: Tony Diaz
Deposited On:09 May 2018 17:10
Last Modified:15 Nov 2021 20:37

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