Equilibrium Initialization and Stability of Three-Dimensional Gas Disks

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We present a new systematic way of setting up galactic gas disks based on the assumption of detailed hydrodynamic equilibrium. To do this, we need to specify the density distribution and the velocity field which supports the disk. We first show that the required circular velocity has no dependence on the height above or below the midplane so long as the gas pressure is a function of density only. The assumption of disks being very thin enables us to decouple the vertical structure from the radial direction. Based on that, the equation of hydrostatic equilibrium together with the reduced Poisson ... continued below

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17 pages

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Wang, Hsiang-Hsu; /Heidelberg, Max Planck Inst. Astron. /ZAH, Heidelberg; Klessen, Ralf S.; /ZAH, Heidelberg /KIPAC, Menlo Park; Dullemond, Cornelis P.; /Heidelberg, Max Planck Inst. Astron. et al. August 25, 2010.

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We present a new systematic way of setting up galactic gas disks based on the assumption of detailed hydrodynamic equilibrium. To do this, we need to specify the density distribution and the velocity field which supports the disk. We first show that the required circular velocity has no dependence on the height above or below the midplane so long as the gas pressure is a function of density only. The assumption of disks being very thin enables us to decouple the vertical structure from the radial direction. Based on that, the equation of hydrostatic equilibrium together with the reduced Poisson equation leads to two sets of second-order non-linear differential equation, which are easily integrated to set-up a stable disk. We call one approach 'density method' and the other one 'potential method'. Gas disks in detailed balance are especially suitable for investigating the onset of the gravitational instability. We revisit the question of global, axisymmetric instability using fully three-dimensional disk simulations. The impact of disk thickness on the disk instability and the formation of spontaneously induced spirals is studied systematically with or without the presence of the stellar potential. In our models, the numerical results show that the threshold value for disk instability is shifted from unity to 0.69 for self-gravitating thick disks and to 0.75 for combined stellar and gas thick disks. The simulations also show that self-induced spirals occur in the correct regions and with the right numbers as predicted by the analytic theory.

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17 pages

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  • Journal Name: Mon.Not.Roy.Astron.Soc. 407:705-720,2010; Journal Volume: 407; Journal Issue: 2

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  • Report No.: SLAC-PUB-14216
  • Grant Number: AC02-76SF00515
  • DOI: 10.1111/j.1365-2966.2010.16942.x | External Link
  • Office of Scientific & Technical Information Report Number: 992912
  • Archival Resource Key: ark:/67531/metadc1012278

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • August 25, 2010

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  • Oct. 14, 2017, 8:36 a.m.

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  • Nov. 2, 2017, 8:11 p.m.

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Wang, Hsiang-Hsu; /Heidelberg, Max Planck Inst. Astron. /ZAH, Heidelberg; Klessen, Ralf S.; /ZAH, Heidelberg /KIPAC, Menlo Park; Dullemond, Cornelis P.; /Heidelberg, Max Planck Inst. Astron. et al. Equilibrium Initialization and Stability of Three-Dimensional Gas Disks, article, August 25, 2010; [California]. (digital.library.unt.edu/ark:/67531/metadc1012278/: accessed December 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.