THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

Federrath, Christoph; Schober, Jennifer; Bovino, Stefano; Schleicher, Dominik R. G.,

doi:10.1088/2041-8205/797/2/L19

Title: THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

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Abstract

The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

Authors:

Federrath, Christoph ^[1]; Schober, Jennifer ^[2]; Bovino, Stefano; Schleicher, Dominik R. G., ^[3]

Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia)
Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany)
Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

Publication Date:: Sat Dec 20 00:00:00 EST 2014

OSTI Identifier:: 22364844

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal Letters

Additional Journal Information:: Journal Volume: 797; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLIFICATION; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; FRAGMENTATION; GALAXIES; JETS; MAGNETIC FIELDS; MAGNETIC REYNOLDS NUMBER; MAGNETISM; MAGNETOHYDRODYNAMICS; MASS; ORIGIN; PLASMA; RESOLUTION; STARS; THREE-DIMENSIONAL CALCULATIONS; TURBULENCE; UNIVERSE

Citation Formats


                    Federrath, Christoph, Schober, Jennifer, Bovino, Stefano, and Schleicher, Dominik R. G.,. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS.  United States: N. p., 2014. 
        Web.  doi:10.1088/2041-8205/797/2/L19.

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                    Federrath, Christoph, Schober, Jennifer, Bovino, Stefano, & Schleicher, Dominik R. G.,. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS.  United States.  https://doi.org/10.1088/2041-8205/797/2/L19

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                    Federrath, Christoph, Schober, Jennifer, Bovino, Stefano, and Schleicher, Dominik R. G.,. 2014.  
        "THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS".  United States.  https://doi.org/10.1088/2041-8205/797/2/L19.

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@article{osti_22364844,

  title        = {THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS},

  author       = {Federrath, Christoph and Schober, Jennifer and Bovino, Stefano and Schleicher, Dominik R. G.,},

  abstractNote = {The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.},

  doi          = {10.1088/2041-8205/797/2/L19},

  url          = {https://www.osti.gov/biblio/22364844},
  journal      = {Astrophysical Journal Letters},

  issn         = {2041-8205},

  number       = 2,

  volume       = 797,

  place        = {United States},

  year         = {Sat Dec 20 00:00:00 EST 2014},

  month        = {Sat Dec 20 00:00:00 EST 2014}

}

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