The magnetohydrodynamics of astrophysical disks, jets, and black holes

Roger D. Blandford, Caltech

Recent astronomical observations, acquired throughout the electromagnetic spectrum, have sharpened our view of what happens when gas accretes onto a black hole. They pose some novel and fascinating fluid dynamical problems which are mostly unsolved. The accreting gas generally has enough angular momentum to form an equatorial disk through which mass flows inward under the action of magnetic torques that must develop when the gas becomes ionized. These accretion disks have to release large amounts of energy and angular momentum. In many instances this occurs through the launching of a pair of relativistic jets perpendicular to the disk plane. In addition, the central black hole, a reservoir itself of extractable energy and angular momentum, can interact with the flow. Recent observations will be briefly summarized and specific, fluid dynamical interpretations of them will be outlined. Some future research opportunities will be described.


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Blandford, R. D., Netzer, H., & Woltjer, L. 1990 "Active Galactic Nuclei", Springer Verlag

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