TIME EVOLUTION OF THE THREE-DIMENSIONAL ACCRETION FLOWS: EFFECTS OF THE ADIABATIC INDEX AND OUTER BOUNDARY CONDITION

Journal Article · Tue Nov 10 04:00:00 EST 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/705/2/1503· OSTI ID:21378267

Janiuk, Agnieszka; Sznajder, Maciej ^[1]; Moscibrodzka, Monika ^[2]; Proga, Daniel ^[3]

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1. Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland)
2. Department of Physics, University of Illinois, Urbana, IL (United States)
3. Department of Physics and Astronomy, University of Nevada, Las Vegas, NV (United States)

We study a slightly rotating accretion flow onto a black hole, using the fully three-dimensional (3D) numerical simulations. We consider hydrodynamics of an inviscid flow, assuming a spherically symmetric density distribution at the outer boundary and a small, latitude-dependent angular momentum. We investigate the role of the adiabatic index and gas temperature, and the flow behavior due to non-axisymmetric effects. Our 3D simulations confirm axisymmetric results: the material that has too much angular momentum to be accreted forms a thick torus near the equator, and the mass accretion rate is lower than the Bondi rate. In our previous study of the 3D accretion flows, for gamma = 5/3, we found that the inner torus precessed, even for axisymmetric conditions at large radii. The present study shows that the inner torus precesses also for other values of the adiabatic index: gamma = 4/3, 1.2, and 1.01. However, the time for the precession to set increases with decreasing gamma. In particular, for gamma = 1.01, we find that depending on the outer boundary conditions, the torus may shrink substantially due to the strong inflow of the non-rotating matter, and the precession will have insufficient time to develop. On the other hand, if the torus is supplied by the continuous inflow of the rotating material from the outer radii, its inner parts will eventually tilt and precess, as was for the larger gamma's.

• OSTI ID: 21378267
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 705; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
ANGULAR MOMENTUM
AXIAL SYMMETRY
BLACK HOLES
BOUNDARY CONDITIONS
COMPUTERIZED SIMULATION
FLUID FLOW
FLUID MECHANICS
GALAXIES
HYDRODYNAMICS
IDEAL FLOW
INCOMPRESSIBLE FLOW
MASS
MATTER
MECHANICS
SIMULATION
STEADY FLOW
SYMMETRY
THREE-DIMENSIONAL CALCULATIONS