Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling MHD accretion-ejection - from the launching area to
  propagation scales   We present results of axisymmetric magnetohydrodynamic (MHD) simulations
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 we have applied {\em
spherical} coordinates for the numerical grid, implying substantial benefits
concerning the numerical resolution and the stability of the simulation. Thanks
to the new setup we were able 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. 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 and angular momentum.
We show that it is the {\em actual} disk magnetization and not so much the
initial magnetization which describes the disk-jet evolution best. Considering
the actual disk magnetization we also find that simulations starting with
different initial magnetization evolve in a similar - typical - way as due to
advection and diffusion the magnetic flux in the disk evolves in time.
Exploring a new, modified diffusivity model we confirm the self-similar
structure of the global jet-launching disk, obtaining power laws for the radial
profiles of the disk physical variables such as density, magnetic field
strength, or accretion velocity.

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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: stat
2
The categories of this paper are: math
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The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci