Accretion Disk Evolution with Wind Infall II. Results of 3D Hydrodynamical Simulations with an Illustrative Application to Sgr A*

Abstract

In the first paper of this series, using analytic tools, we examined how the evolution and structure of a massive accretion disk may be influenced by the deposition of mass and angular momentum by an infalling Bondi-Hoyle wind. Such a mass influx impacts the long-term behavior of the disk by providing additional sources of viscosity and heating. Here, we make improvements over this earlier work by incorporating the results of 3D hydrodynamical simulations of the large scale accretion from an ambient medium into the disk evolution equations developed previously. We discuss two models, one with the axis of the disk parallel to, and the second with the axis oriented perpendicular to the large scale Bondi-Hoyle flow. We find that the mass inflow rate onto the disk within logarithmic annuli is roughly constant with radius and that the impacting wind carries much less specific angular momentum than Keplerian. We also find, in general, that the infrared spectrum of a wind-fed disk system is steeper than that of a Shakura-Sunyaev configuration, due mainly to the dissipation of the wind's kinetic energy at the disk's surface. In applying our results to the Galactic Center black hole candidate, Sgr A*, we demonstrate that a high wind inflow rate of order 10^-4 solar masses per year cannot be incorporated into a fossil disk without a significant dissipation of kinetic energy at all radii. Such a high dissipation would violate current infrared and near-infrared limits on the observed spectrum of Sgr A*.

30 pages, 31 figures, uses aaspp4.sty, submitted to ApJ

References in corpus (2)

• On the Fate of Gas Accreting at a Low Rate onto a Black Hole
• Hydrodynamical Accretion Onto Sgr A* From Distributed Point Sources

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• The Spectrum and Variability of Circular Polarization in Sagittarius A* from 1.4 to 15 GHz
• First proper motions of thin dust filaments at the Galactic Center
• X-ray flares from Sgr A*: star-disk interactions?
• Either neutralino dark matter or cuspy dark halos
• MHD Simulations of Accretion onto Sgr A*: Quiescent Fluctuations, Outbursts, and Quasi-Periodicity
• Direct Feeding of the Black Hole at the Galactic Center with Radial Gas Streams from Close-In Stellar Winds
• Advection-Dominated Accretion with Infall and Outflows
• Coordinated multi-wavelength observations of Sgr A*
• The Jet in the Galactic Center: An Ideal Laboratory for Magnetohydrodynamics and General Relativity
• SgrA* emission at 7mm: variability and periodicity