Long Term Simulations of Astrophysical Jets Energy Structure and QuasiPeriodic Ejection

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Long Term Simulations of Astrophysical Jets
Energy Structure and Quasi-Periodic Ejection
Ahmed Ibrahim Kyoto University D4
Collaborators K. Shibata K. Uehara
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Observational evidences
HST WFPC2 image of the L1551 IRS5 jet. The low
mass young stellar object
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Numerical Method
- As an initial condition, we assume an
equilibrium disk rotating in a central
point-mass gravitational potential (Matsumoto et
al. 1996). The initial magnetic field is
assumed to be uniform and parallel to the
axis of rotation - As a boundary condition, we
assume the side and top surfaces are free
boundaries. - The numerical schemes we use are
the cubic interpolated propagation (CIP) method
(Yabe Aoki 1991 Yabe et al. 1991) and the
method of characteristics-constrained transport
(MOCCT) (evans Hawley 1988 Stone Norman 1992).
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Numerical results
The time evolution of the density and temperature
at magnetic energy 2x10-6
1-Torsional Alfven wave is generated at the disk
surface and propagates up into the corona
1-Torsional Alfven wave is generated at the disk
surface and propagates up into the corona
1-Torsional Alfven wave is generated at the disk
surface and propagates up into the corona
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Mass accretion is defined as
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Mass flux outflowdefined as

• What is the relation between the time peak and
  the initial magnetic field strength

The jet is ejected intermittently
Toroidal flux outflow
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Conclusions
1-Accretion flow state and behaviour of jet
strongly coupled. 2-There is a common pattern
of behaviour in mass ejection which might be
explained by untwisted toroidal magnetic
field 3The poynting flux is dominated over both
the kinetic energy flux and enthalpy flux
specially at strong initial magnetic field
Future work
Extend the simulation to 3d-dimenstional long
term simulation
The end