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An Accretion-Ejection Instability in magnetized disks

M. Tagger·R. Pellat
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Abstract

We present an instability occurring in the inner part of disks threaded by a moderately strong vertical (poloidal) magnetic field. Its mechanism is such that a spiral density wave in the disk, driven by magnetic stresses (rather than self-gravity as in galactic spirals), becomes unstable by exchanging angular momentum with a Rossby vortex it generates at its corotation radius. This angular momentum can then ``leak'' as Alfven waves emitted toward the corona of the disk thus providing, as an element of the accretion process, an energetic source for a wind or a jet. As galactic spirals, this instability forms low azimuthal wavenumber, standing spiral patterns which might provide an explanation for low-frequency QPOs in low-mass X-ray binaries.

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M. Tagger, R. Pellat. 1999-07-20. An Accretion-Ejection Instability in magnetized disks. https://arxiv.org/abs/astro-ph/9907267

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