Journal Article

A magnetohydrodynamical model for the formation of episodic jets

Feng Yuan, Jun Lin, Kinwah Wu and Luis C. Ho

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 395, issue 4, pages 2183-2188
Published in print June 2009 | ISSN: 0035-8711
Published online May 2009 | e-ISSN: 1365-2966 | DOI:
A magnetohydrodynamical model for the formation of episodic jets

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Episodic ejection of plasma blobs has been observed in many black hole systems. While steady, continuous jets are believed to be associated with large-scale open magnetic fields, what causes the episodic ejection of blobs remains unclear. Here by analogy with the coronal mass ejection on the Sun, we propose a magnetohydrodynamical model for episodic ejections from black holes associated with the closed magnetic fields in an accretion flow. Shear and turbulence of the accretion flow deform the field and result in the formation of a flux rope in the disc corona. Energy and helicity are accumulated and stored until a threshold is reached. The system then loses its equilibrium and the flux rope is thrust outward by the magnetic compression force in a catastrophic way. Our calculations show that for parameters appropriate for the black hole in our Galactic centre, the plasmoid can attain relativistic speeds in about 35 min.

Keywords: accretion, accretion discs; black hole physics; MHD; ISM: jets and outflow

Journal Article.  4564 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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