NUMERICAL SIMULATION OF HOT ACCRETION FLOWS. II. NATURE, ORIGIN, AND PROPERTIES OF OUTFLOWS AND THEIR POSSIBLE OBSERVATIONAL APPLICATIONS

By F. Yuan, De-Fu Bu, Maochun Wu. 2012

169 citations recorded by the source corpus.

Hydrodynamical (HD) and magnetohydrodynamical (MHD) numerical simulations of hot accretion flows have indicated that the inflow accretion rate decreases inward. Two models have been proposed to explain this result. In the adiabatic inflow–outflow solution (ADIOS), this is because of the loss of gas in the outflow. In the alternative convection-dominated accretion flow model, it is thought that the flow is convectively unstable and gas is locked in convective eddies. We investigate the nature of the inward decrease of the accretion rate using HD and MHD simulations. We calculate various properties of the inflow and outflow such as temperature and rotational velocity. Systematic and significant differences are found. These results suggest that the inflow and outflow are not simply convective turbulence; instead, systematic inward and outward motion (i.e., real outflow) must exist. We have also analyzed the convective stability of MHD accretion flows and found that they are stable. These results favor the ADIOS scenario. We suggest that the mechanisms of producing outflow in HD and MHD flows are the buoyancy associated with the convection and the centrifugal force associated with the angular momentum transport mediated by the magnetic field, respectively. The latter is similar to the Blandford & Payne mechanism but no large-scale open magnetic field is required. We discuss some possible observational applications, including the Fermi bubble in the Galactic center and winds in active galactic nuclei and black hole X-ray binaries.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/74084760ddfbda80fdfc11702084c9956d0d391e

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In Astronomy and Astrophysics

1. Ramesh Narayan
2. A. Sa̧dowski
3. F. Yuan
4. Xue-Ning Bai
5. Yucong Zhu
6. F. Xie
7. James M. Stone
8. A. Tchekhovskoy

In Nuclear and High Energy Physics

1. Ramesh Narayan
2. A. Sa̧dowski
3. F. Yuan
4. F. Xie
5. A. Kulkarni
6. R. Penna
7. Yucong Zhu
8. James M. Stone

Citations in the corpus

• GRMHD simulations of magnetized advection‐dominated accretion on a non‐spinning black hole: role of outflows (2012, background): “Yuan et al. (2012b) estimate from their large dynamic range 2D hydrodynamic simulations that s ∼0.4–0.5.”
• LOCAL STUDY OF ACCRETION DISKS WITH A STRONG VERTICAL MAGNETIC FIELD: MAGNETOROTATIONAL INSTABILITY AND DISK OUTFLOW (2012, background): “Significant outflow has been reported in two-dimensional MHD simulations (Stone & Pringle 2001; Yuan et al. 2012), where MRI is a transient phenomenon.”
• Hot Accretion Flows Around Black Holes (2014, methodology): “Typically, the jet dominates the energy output, whereas the wind dominates the momentum output (Yuan et al. 2012a, Sadowski et al. 2013a).”
• Radiative efficiency of hot accretion flows (2012, background): “Yuan et al. (2012b) have found that the profile of Ṁ(R) has two parts.”
• Energy, momentum and mass outflows and feedback from thick accretion discs around rotating black holes (2013, background): “Roughly, it appears that 0.5 < s < 0.7 (in agreement with Yuan et al. 2012b).”