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The MPIA conference series
at Ringberg Castle
The MPIA conference series
at Ringberg Castle
 
EPoS 2020 Suggested Contribution
Turbulent dynamo in a weakly ionized medium

Siyao Xu
UW-Madison, Madison, US
Both turbulence and magnetic fields are ubiquitous in the Universe and exist across a vast range of length scales. Turbulence accounts for the growth and maintenance of cosmic magnetic fields via the small-scale turbulent dynamo (SSTD), resulting in the magnetized interstellar, intracluster, and intergalactic media. In the cold gases where stars form, the SSTD occurs at a low ionization fraction. The importance of ionization fraction for the SSTD during star formation was not considered in earlier studies. The weak coupling between neutrals and ions leads to inefficient dynamo growth of magnetic fields. The unique linear-in-time growth of magnetic field strength in the weakly coupled regime was first predicted by our dynamo theory and has been recently confirmed by the first supercomputer two-fluid (neutral+ionized fluids) dynamo simulation at a low ionization fraction. This result has important implications for the magnetic field amplification during the formation of both first stars and local stars.
Caption: Dynamo growth of magnetic fields in a weakly ionized medium. A comparison between our analytic predictions (lines) and two-fluid numerical measurements (circles).
Collaborators:
A. Lazarian, UW-Madison, US
D.S. Balsara, U Notre Dame, US
S.K. Garain, U Notre Dame, US
Key publication

Suggested Session: Turbulence