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Issue A&A
Volume 398, Number 3, February II 2003
Page(s) 825 - 844
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20021699



A&A 398, 825-844 (2003)
DOI: 10.1051/0004-6361:20021699

Structured outflow from a dynamo active accretion disc

B. von Rekowski, A. Brandenburg, W. Dobler and A. Shukurov

Department of Mathematics, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK
(Received 25 May 2000 / Accepted 14 November 2002 )

Abstract
We present an axisymmetric numerical model of a dynamo active accretion disc. If the dynamo-generated magnetic field in the disc is sufficiently strong (close to equipartition with thermal energy), a fast magneto-centrifugally driven outflow develops within a conical shell near the rotation axis, together with a slower pressure driven outflow from the outer parts of the disc as well as around the axis. Our results show that a dynamo active accretion disc can contribute to driving an outflow even without any external magnetic field. The fast outflow in the conical shell is confined by the azimuthal field which is produced by the dynamo in the disc and advected to the disc corona. This part of the outflow has high angular momentum and is cooler and less dense than its surroundings. The conical shell's half-opening angle is typically about $30^\circ$ near the disc and decreases slightly with height. The slow outflow is hotter and denser.


Key words: ISM: jets and outflows -- accretion, accretion disks -- magnetic fields -- MHD

Offprint request: B. von Rekowski, Brigitta.vonRekowski@astro.uu.se




© ESO 2003

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