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Statistical simulation of the magnetorotational dynamo.
J Squire1, A Bhattacharjee1,2
1Department of Astrophysical Sciences and Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA.
Physical Review Letters
|March 14, 2015
Summary
Homogenous turbulence is unstable to large-scale dynamo instability, saturating to an equilibrium dependent on the magnetic Prandtl number (Pm). Simplified models offer insights into astrophysical regimes.
Area of Science:
- Plasma physics
- Astrophysics
- Magnetohydrodynamics
Background:
- Magnetorotational instability (MRI) drives turbulence and dynamos in astrophysical systems.
- Understanding turbulence and magnetic field generation is crucial for accretion disks and stellar interiors.
Purpose of the Study:
- Analyze turbulence and dynamo effects induced by MRI.
- Investigate the role of the magnetic Prandtl number (Pm) in saturation and transport.
- Assess the utility of simplified quasilinear models.
Main Methods:
- Employed quasilinear statistical simulation methods.
- Analyzed homogeneous turbulence for dynamo instability.
- Studied saturation to inhomogeneous equilibrium.
Main Results:
- Homogeneous turbulence is unstable to a large-scale dynamo instability.
- The dynamo saturates to an inhomogeneous equilibrium strongly dependent on the magnetic Prandtl number (Pm).
- Angular momentum transport dependence on Pm in the quasilinear model mirrors nonlinear MRI turbulence.
Conclusions:
- The large-scale dynamo is a critical factor in MRI turbulence.
- Simplified quasilinear models can provide valuable insights into astrophysically relevant low or high Pm regimes.
- Quasilinear models effectively capture essential physics despite reduced nonlinearity.
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