TY  - GEN
A1  - Stepanovs, Deniss
N2  - The results of three-dimensional, axisymmetric, magnetohydrodynamic simulations are presented, investigating the 
launching of jets and outflows from a magnetically diffusive accretion disk.
The time evolution of the disk structure is self--consistently taken into account.
In contrast to previous works, spherical coordinates for the numerical grid were applied.
The new setup made it possible to run simulations for more than 150,000 dynamical times 
on a domain extending 1500 inner disk radii with a resolution of up to 24 cells per 
disk height in the inner disk.
This, in fact, is the longest and resolved simulation performed so far.

A novel approach to the analysis of disk-jet system was developed
and interrelations between the properties of the jet and the underlying disk were derived.
Using this method, it was shown that it is the actual disk magnetization that best describes the disk--jet evolution.
The actual disk magnetization at the jet foot point is
the main parameter that governs the properties of the jet, namely all jet steady-state MHD integrals.
Depending on the disk magnetization, jet launching occurs in two different but complementary
regimes - jets driven predominantly by centrifugal or magnetic forces. 
These regimes differ in the ejection efficiency concerning mass, energy, angular momentum, and all jet integrals.

The self-generation of the magnetic field by a Alpha-Omega mean-field dynamo was also addressed.
In this setup, the magnetic flux is continuously generated, diffuses outwards the disk, and fills the entire disk.
A magnetic field of the inner disk is similar to open 
field structure, favoring magneto-centrifugal launching.
The outer disk field is highly inclined and predominantly radial. 
The differential rotation induces a strong toroidal component that plays the key role in the outflow launching.
These outflows from the outer disk are slower, denser, and less collimated.
A toy--model triggering a time-dependent mean-field dynamo was invented.
The general result is that the episodic ejection and large-scale jet knots can be steered
by a time-dependent dynamo that regenerates the jet-launching magnetic field.
TI  - Launching Jets and Outflows from Magnetized Accretion Disks. Adection, Diffusion, Dynamo.
Y1  - 2014///
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/17782/
ID  - heidok17782
AV  - public
ER  -