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Issue A&A
Volume 455, Number 3, September I 2006
Page(s) 779 - 784
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361:20064863



A&A 455, 779-784 (2006)
DOI: 10.1051/0004-6361:20064863

Generation of the magnetic field in jets

V. Urpin1, 2

1  Departament de Física Aplicada, Universitat d'Alacant, Ap. Correus 99, 03080 Alacant, Spain
    e-mail: vadim.urpin@uv.es
2  A.F. Ioffe Institute of Physics and Technology and Isaak Newton Institute of Chili, Branch in St. Petersburg, 194021 St. Petersburg, Russia

(Received 16 January 2006 / Accepted 17 April 2006)

Abstract
We consider dynamo action under the combined influence of turbulence and large-scale shear in sheared jets. Shear can stretch turbulent magnetic field lines in such a way that even turbulent motions showing mirror symmetry become suitable for generation of a large-scale magnetic field. We derive the integral induction equation governing the behaviour of the mean field in jets. The main result is that sheared jets may generate a large-scale magnetic field if shear is sufficiently strong. The generated mean field is mainly concentrated in a magnetic sheath surrounding the central region of a jet, and it exhibits sign reversals in the direction of the jet axis. Typically, the magnetic field in a sheath is dominated by the component along the jet that can reach equipartition with the kinetic energy of particles. The field in the central region of jets has a more disordered structure.


Key words: magnetohydrodynamics (MHD) -- ISM: jets and outflows -- galaxies: jets -- ISM: magnetic fields -- gravitational lensing -- magnetic fields



© ESO 2006


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