Evolution of accretion tori orbiting black holes - I. Theory

Abramowicz, Marek A.; Henderson, Paul F.; Ghosh, Pranab

doi:10.1093/mnras/203.2.323

Cited by 6 publications

(4 citation statements)

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“…In the PD models it was assumed that H(R) corresponds to the photosphere location, however, as checked by Abramowicz et al (1983), this in general is not the case. Therefore, as in the case of GRRMHD simulations discussed above, but for different reasons, the relation between the shape of the accretion flow and the radiation transfer is not straightforward.…”

Section: Polish Doughnutsmentioning

confidence: 99%

The slimming effect of advection on black-hole accretion flows

Lasota

Vieira

Sądowski

et al. 2016

A&A

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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.

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Section: Polish Doughnutsmentioning

confidence: 99%

The slimming effect of advection on black-hole accretion flows

Lasota

Vieira

Sądowski

et al. 2016

A&A

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“…However, perturbations perpendicular to the orbital plane can also be important. 4 For the above-mentioned exact solutions of Einstein's equations, the frequencies of vertical oscillations were given explicitly [311].…”

Section: Essential Features Of the Stationary Axisymmetric Spacetimesmentioning

confidence: 99%

“…The relativistic Euler equation can be integrated in terms of specific enthalpy, W ≡ − (ǫ + P ) −1 dP = ln |u t | − F (l), which can be further expressed as a function of l(R, z), the profile of angular momentum density [4,5,12,185]. The only unknown function that needs to be specified is the rotation law, either in terms of l = −u φ /u t (which is a conserved quantity), or angular velocity Ω = u φ /u t .…”

Section: Solving Einstein's Equations For a Black Hole With Matter Ar...mentioning

confidence: 99%

Gravitating discs around black holes

Karas

Huré

Semerák

2004

Class. Quantum Grav.

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Abstract. Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole-disc system by analytical solutions of stationary, axially symmetric Einstein's equations. Then, more detailed considerations are focused to middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate.Within general relativity, only a static case has been analysed in detail. Results are often very inspiring, however, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging and completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the environment around. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star-disc interactions, which can be recognised in observational properties, such as the relation between the central mass and stellar velocity dispersion.

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“…We also plan to calculate models of ion tori in a non-Kerr background (as advocated by Psaltis and collaborators, e.g., Psaltis et al 2008;Johannsen & Psaltis 2010) to possibly constrain gravity in the strong-field regime of alternative gravity theories to Einstein's general relativity. In the context of flares it may also be interesting to examine non-stationary ion tori (as in Abramowicz et al 1983). …”

Section: Discussionmentioning

confidence: 99%

Modelling the black hole silhouette in Sagittarius A* with ion tori

Straub¹,

Vincent²,

Abramowicz³

et al. 2012

A&A

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We calculate the "observed at infinity" image and spectrum of the accretion structure in Sgr A*, by modelling it as an optically thin, constant angular momentum ion torus in hydrodynamic equilibrium. The physics we consider includes a two-temperature plasma, a toroidal magnetic field, as well as radiative cooling by bremsstrahlung, synchrotron, and inverse Compton processes. Our relativistic model has the virtue of being fully analytic and very simple, depending only on eight tunable parameters: the black hole spin and the inclination of the spin axis to our line of sight, the torus angular momentum, the polytropic index, the magnetic to total pressure ratio, the central values of density and electron temperature, and the ratio of electron to ion temperatures. The observed image and spectrum are calculated numerically using the ray-tracing code GYOTO. Our results demonstrate that the ion torus model is able to account for the main features of the accretion structure surrounding Sgr A*.

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Evolution of accretion tori orbiting black holes - I. Theory

Cited by 6 publications

References 0 publications

The slimming effect of advection on black-hole accretion flows

The slimming effect of advection on black-hole accretion flows

Gravitating discs around black holes

Modelling the black hole silhouette in Sagittarius A* with ion tori

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