Magnetohydrodynamic numerical simulation of wind production from hot accretion flows around black holes at very large radii

Journal Article · Wed Jun 01 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/823/2/90· OSTI ID:22869058

Bu, De-Fu; Yuan, Feng; Gan, Zhao-Ming ^[1]; Yang, Xiao-Hong ^[2]

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1. Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 (China)
2. Department of Physics, Chongqing University, Chongqing 400044 (China)

Numerical simulations of hot accretion flows around black holes have shown the existence of strong wind. Those works focused only on the region close to the black hole and thus it is unknown whether or where the wind production stops at large radii. To address this question, we have recently performed hydrodynamic (HD) simulations by taking into account the gravitational potential of both the black hole and the nuclear star cluster. The latter is assumed to be proportional to σ{sup 2}ln(r), with σ being the velocity dispersion of stars and r the distance from the center of the galaxy. It was found that when the gravity is dominated by nuclear stars, i.e., outside a radius R{sub A}≡GM{sub BH}/σ{sup 2}, winds can no longer be produced. That work, however, neglects the magnetic field, which is believed to play a crucial dynamical role in the accretion and thus must be taken into account. In this paper, we revisit this problem by performing magnetohydrodynamic (MHD) simulations. We confirm the result of our previous paper, namely that wind cannot be produced in the region R>R{sub A}. Our result, combined with recent results of Yuan et al., indicates that the formula describing the mass flux of wind, M-dot {sub wind}= M-dot {sub BH}(r/20r{sub s}), can only be applied to the region where the black hole potential is dominant. Here M-dot {sub BH} is the mass accretion rate at the black hole horizon and the value of R {sub A} is similar to the Bondi radius.

• OSTI ID: 22869058
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 823; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
COMPUTERIZED SIMULATION
DISPERSIONS
DISTANCE
GALAXIES
GRAVITATION
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MASS
STAR CLUSTERS
STARS
STELLAR WINDS