Angular momentum transport in quasi-Keplerian accretion disks

P Subramanian, BS Pujari, PA Becker - Journal of Astrophysics and …, 2004 - Springer
Journal of Astrophysics and Astronomy, 2004Springer
We reexamine arguments advanced by Hayashi & Matsuda (2001), who claim that several
simple, physically motivated derivations based on mean free path theory for calculating the
viscous torque in a quasi-Keplerian accretion disk yield results that are inconsistent with the
generally accepted model. If correct, the ideas proposed by Hayashi & Matsuda would
radically alter our understanding of the nature of the angular momentum transport in the
disk, which is a central feature of accretion disk theory. However, in this paper we point out …
Abstract
We reexamine arguments advanced by Hayashi & Matsuda (2001), who claim that several simple, physically motivated derivations based on mean free path theory for calculating the viscous torque in a quasi-Keplerian accretion disk yield results that are inconsistent with the generally accepted model. If correct, the ideas proposed by Hayashi & Matsuda would radically alter our understanding of the nature of the angular momentum transport in the disk, which is a central feature of accretion disk theory. However, in this paper we point out several fallacies in their arguments and show that there indeed exists a simple derivation based on mean free path theory that yields an expression for the viscous torque that is proportional to the radial derivative of the angular velocity in the accretion disk, as expected. The derivation is based on the analysis of the epicyclic motion of gas parcels in adjacent eddies in the disk.
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