Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2009-06-15
Astrophys.J.707:428-445,2009
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
45 pages, 17 figures, 1 movie; ApJ accepted; updated version contains several new figures and a movie detailing the operation
Scientific paper
10.1088/0004-637X/707/1/428
We report on a global, three-dimensional GRMHD simulation of an accretion torus embedded in a large scale vertical magnetic field orbiting a Schwarzschild black hole. This simulation investigates how a large scale vertical field evolves within a turbulent accretion disk and whether global magnetic field configurations suitable for launching jets and winds can develop. We find that a "coronal mechanism" of magnetic flux motion, which operates largely outside the disk body, dominates global flux evolution. In this mechanism, magnetic stresses driven by orbital shear create large-scale half-loops of magnetic field that stretch radially inward and then reconnect, leading to discontinuous jumps in the location of magnetic flux. In contrast, little or no flux is brought in directly by accretion within the disk itself. The coronal mechanism establishes a dipole magnetic field in the evacuated funnel around the orbital axis with a field intensity regulated by a combination of the magnetic and gas pressures in the inner disk. These results prompt a reevaluation of previous descriptions of magnetic flux motion associated with accretion. Local pictures are undercut by the intrinsically global character of magnetic flux. Formulations in terms of an "effective viscosity" competing with an "effective resistivity" are undermined by the nonlinearity of of the magnetic dynamics and the fact that the same turbulence driving mass motion (traditionally identified as "viscosity") can alter magnetic topology.
Beckwith Kris
Hawley John F.
Krolik Julian H.
No associations
LandOfFree
Transport of Large Scale Poloidal Flux in Black Hole Accretion does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Transport of Large Scale Poloidal Flux in Black Hole Accretion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transport of Large Scale Poloidal Flux in Black Hole Accretion will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-475004