Open AccessAligning spinning black holes and accretion discs
Author(s) -
King A. R.,
Lubow S. H.,
Ogilvie G. I.,
Pringle J. E.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09378.x
Subject(s) - physics , angular momentum , astrophysics , black hole (networking) , accretion (finance) , supermassive black hole , rotating black hole , spinning , torque , spin flip , total angular momentum quantum number , accretion disc , supernova , spin (aerodynamics) , astronomy , classical mechanics , galaxy , quantum mechanics , mechanical engineering , computer network , routing protocol , routing (electronic design automation) , computer science , engineering , thermodynamics , link state routing protocol
We consider the alignment torque between a spinning black hole and an accretion disc whose angular momenta are misaligned. This situation must hold initially in almost all gas accretion events on to supermassive black holes, and may occur in binaries where the black hole receives a natal supernova kick. We show that the torque always acts to align the hole's spin with the total angular momentum without changing its magnitude. The torque acts dissipatively on the disc, reducing its angular momentum, and aligning it with the hole if and only if the angle θ between the angular momenta J d of the disc and J h of the hole satisfy the inequality cos θ > − J d /2 J h . If this condition fails, which requires both θ > π/2 and J d < 2 J h , the disc counteraligns.