At super-Eddington rates accretion flows onto black holes have been described
as slim (aspect ratio $H/R \lesssim 1$) 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. We wish to establish under
what conditions slim accretion flows become thick. 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.We find that
the dominant effect of advection at high accretion rates precludes slim discs
becoming thick. At super-Eddington rates accretion flows around black holes can
always be considered slim rather than thick.Comment: 8 pages, 5 figures. Astronomy & Astrophysics, in pres

Abramowicz, M. A.

Lasota, J. -P.

Narayan, R.

Sadowski, A.

Vieira, R. S. S.

Astronomy and Astrophysics

English

arXiv

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

Lasota, J. P.

Abramowicz, Marek A,

Swepub

The slimming effect of advection on black-hole accretion flows

International audienceContext. At super-Eddington rates accretion flows onto black holes have been described as slim (aspect ratio H/R ≲ 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

Lasota, J.-P.

HAL: Hyper Article en Ligne

J.-P. Lasota

R. S. S. Vieira

A. Sadowski

R. Narayan

M. A. Abramowicz

Crossref

HAL-INSU

Context. At super-Eddington rates accretion flows onto black holes have been described as slim (aspect ratio H/R ≲ 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

EDP Sciences OAI-PMH repository (1.2.0)

We study energy flows in geometrically thick accretion discs, both optically thick and thin, using general relativistic, three-dimensional simulations of black hole accretion flows. We find that for non-rotating black holes the efficiency of the total feedback from thick accretion discs is 3% - roughly half of the thin disc efficiency. This amount of energy is ultimately distributed between outflow and radiation, the latter scaling weakly with the accretion rate for supercritical accretion rates, and returned to the interstellar medium. Accretion on to rotating black holes is more efficient because of the additional extraction of rotational energy. However, the jet component is collimated and likely to interact only weakly with the environment, whereas the outflow and radiation components cover a wide solid angle.AstronomyAccepted Manuscrip

Vieira, Rebecca

Sadowski, Aleksander

Narayan, Ramesh

Harvard University - DASH

The slimming effect of advection on black-hole accretion flows

Abstract

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