EDP Sciences
Free access
Volume 367, Number 3, March I 2001
Page(s) 1095 - 1111
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20000535

A&A 367, 1095-1111 (2001)
DOI: 10.1051/0004-6361:20000535

Numerical simulations of the accretion-ejection instability in magnetised accretion disks

S. E. Caunt and M. Tagger

DSM/DAPNIA/Service d'Astrophysique (CNRS URA 2052), CEA Saclay, 91191 Gif-sur-Yvette, France

(Received 31 August 2000 / Accepted 15 December 2000)

The Accretion-Ejection Instability (AEI) described by Tagger & Pellat (1999, hereafter TP99) is explored numerically using a global 2d model of the inner region of a magnetised accretion disk. The disk is initially currentless but threaded by a vertical magnetic field created by external currents, and frozen in the flow. In agreement with the theory a spiral instability, similar in many ways to those observed in self-gravitating disks, develops when the magnetic field is, within a factor of a few, at equipartition with the disk thermal pressure. Perturbations in the flow build up currents and create a perturbed magnetic field within the disk. The present non-linear simulations give good evidence that such an instability can occur in the inner region of accretion disks, and generate accretion of gas and vertical magnetic flux toward the central object, if the equilibrium radial profiles of density and magnetic flux exceed a critical threshold.

Key words: magnetohydrodynamics -- instabilities -- accretion: accretion disks -- galaxies: jets

Offprint request: S. E. Caunt, scaunt@sun3.oulu.fi

SIMBAD Objects in preparation

© ESO 2001