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Astron. Astrophys. 331, 1143-1146 (1998)
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Research Note
On the runaway instability of relativistic tori *
Marek A. Abramowicz 1, 3, 4,
Vladimír Karas 2 and
Antonio Lanza 3
1 Department of Astronomy and Astrophysics, Göteborg
University and Chalmers University of Technology,
S-412 96 Göteborg, Sweden (marek@tfa.fy.chalmers.se)
2 Astronomical Institute, Charles University, Faculty of
Mathematics and Physics,
V Hole
ovi
kách 2,
CZ-180 00 Praha, Czech Republic (karas@mbox.cesnet.cz)
3 Scuola Internazionale Superiore di Studi Avanzati, Via
Beirut 2-4, I-34 014 Trieste, Italy (lanza@sissa.it)
4 International Centre for Theoretical Physics, Strada
Costiera 11, I-34 014 Trieste, Italy
Received 15 September 1997 / Accepted 30 October 1997
Abstract
We further investigate the runaway instability of relativistic tori around black holes assuming a power law distribution of the specific angular momentum. We neglect the self-gravity of the torus; thus the gravitational field of the system is determined by the central rotating black hole alone (the Kerr geometry). We find that for any positive (i.e. consistent with the local Rayleigh stability condition) power law index of the angular momentum distribution, the tori are always runaway stable for a sufficiently large spin of the black hole. However, before concluding that some (astrophysically realistic) tori could indeed be runaway stable, one should include, in full general relativity, the destabilizing effect of self-gravity.
Key words: accretion:
accretion-discs 
black hole
physics
instabilities
* Work prepared during The Annual Nordic-Trieste Astrophysics Workshop (ICTP, Trieste 1997)
Send offprint requests to: V. Karas
Contents
- 1. Introduction
- 2. The runaway instability
- 3. Numerical procedure
- 4. Results and conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: March 3, 1998
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