Effect of a Magneto-Rotational Instability on Jets from Accretion Disks
Abstract
We present the results of 2.5-dimensional MHD simulations of jet formation from accretion disks that are unstable for a magneto-rotational instability. Numerical simulations show that magnetically driven jets are ejected from magneto-rotationally-unstable disks. The velocities of the jets are of the order of the Keplerian velocities of the disks. In this paper, we mainly focus on the effect of the magneto-rotational instability on magnetically driven jets from thick disks. For that purpose, we initially impose a sinusoidal perturbation with finite amplitude on a rotating disk that is threaded by a vertical uniform magnetic field. The perturbation grows by the magneto-rotational instability, and the nonlinear development of the instability leads to a channel flow which causes violent accretion. As the accretion continues, the accretion flow is partially turned outward to the outflow that is accelerated by the magnetic force along the poloidal magnetic field line, i.e., a ma gnetically driven jet is produced. Models with initial finite amplitude perturbation (i.e., |δv|/Vs = 0.1 where δv is the velocity perturbation and is the sound velocity) are compared with those without any perturbation that we previously studied. The mass-accretion rate, mass-ejection rate, and jet velocity are larger when the perturbation is imposed on in the disk. However, the jet velocity is of the order of the Keplerian velocity of the disk, almost independent of the perturbation.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- February 2002
- DOI:
- 10.1093/pasj/54.1.121
- Bibcode:
- 2002PASJ...54..121K
- Keywords:
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- ACCRETION DISKS;
- INSTABILITIES;
- JETS;
- METHODS: NUMERICAL;
- MHD