The slimming effect of advection on black-hole accretion flows

Context. At super-Eddington rates accretion flows onto black holes have been described as slim (aspect ratio H/R less than or similar to 1) or thick (H/R > 1) discs, also known as tori or (Polish) doughnuts. The relation between the two descriptions has never been established, but it was commonly believed that at sufficiently high accretion rates slim discs inflate, becoming thick. Aims. We wish to establish under what conditions slim accretion flows become thick. Methods. We use analytical equations, numerical 1 + 1 schemes, and numerical radiative MHD codes to describe and compare various accretion flow models at very high accretion rates. Results. We find that the dominant effect of advection at high accretion rates precludes slim discs becoming thick. Conclusions. At super-Eddington rates accretion flows around black holes can always be considered slim rather than thick.

NATURVETENSKAP Fysik Astronomi, astrofysik och kosmologi hsv//swe
NATURAL SCIENCES Physical Sciences Astronomy, Astrophysics and Cosmology hsv//eng
accretion
accretion disks
black hole physics
relativistic magnetohydrodynamic simulations
super-eddington accretion
x-ray sources
dominated accretion
thick accretion
vertical structure
polish doughnuts
tidal disruption
disk model
jets

Vieira, R. S. S. (author)
Sadowski, A. (author)
Narayan, R. (author)
Abramowicz, Marek A,1945Gothenburg University,Göteborgs universitet,Institutionen för fysik (GU),Department of Physics (GU)(Swepub:gu)xabrma (author)
Göteborgs universitetInstitutionen för fysik (GU) (creator_code:org_t)

By the author/editor: Lasota, J. P.; Vieira, R. S. S.; Sadowski, A.; Narayan, R.; Abramowicz, Mare ...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Astronomy Astrop ...

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