Anomalous magnetic viscosity in relativistic accretion disks

Lin, Fu-Jun; Liu, Sanqiu; Li, Xiaoqing

doi:10.1016/j.newast.2012.11.002

Cited by 2 publications

(3 citation statements)

References 27 publications

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“…The standard model of thin accretion disks proposed by Shakura & Sunyaev (1973), and extended to be relativistic by Novikov & Thorne (1973), considers angular momentum to be transported radially through internal torques (generated by magnetically induced ‘viscosity’ – see Lynden-Bell 1969; Shakura & Sunyaev 1973; Lin, Liu, & Xiaoqing 2013), in addition to removal from photons, in an accretion disk whose structure is completely stable (i.e. not a function of time).…”

Section: Radiating and Scattering Away Angular Momentummentioning

confidence: 99%

“…Because photons are unable to remove all the necessary angular momentum if they remove all the necessary energy, some other mechanism must remove angular momentum, which consequently must alter the energy liberated by photons too. The standard model of thin accretion disks proposed by Shakura & Sunyaev (1973), and extended to be relativistic by Novikov & Thorne (1973), considers angular momentum to be transported radially through internal torques (generated by magnetically induced 'viscosity' -see Lynden-Bell 1969;Shakura & Sunyaev 1973;Lin, Liu, & Xiaoqing 2013), in addition to removal from photons, in an accretion disk whose structure is completely stable (i.e. not a function of time).…”

Section: Relatively Isotropic Emission With Internal Angular-momentummentioning

confidence: 99%

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Liberation of Specific Angular Momentum Through Radiation and Scattering in Relativistic Black-Hole Accretion Disks

Stevens

2015

Publ. Astron. Soc. Aust.

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A key component of explaining the array of galaxies observed in the Universe is the feedback of active galactic nuclei, each powered by a massive black hole's accretion disk. For accretion to occur, angular momentum must be lost by that which is accreted. Electromagnetic radiation must offer some respite in this regard, the contribution for which is quantified in this paper, using solely general relativity, under the thin-disk regime. Herein, I calculate extremised situations where photons are entirely responsible for energy removal in the disk and then extend and relate this to the standard relativistic accretion disk outlined by Novikov & Thorne, which includes internal angular-momentum transport. While there is potential for the contribution of angular-momentum removal from photons to be 1% out to ∼10 4 Schwarzschild radii if the disk is irradiated and maximally liberated of angular momentum through inverse Compton scattering, it is more likely of order 10 2 Schwarzschild radii if thermal emission from the disk itself is stronger. The effect of radiation/scattering is stronger near the horizons of fast-spinning black holes, but, ultimately, other mechanisms must drive angular-momentum liberation/transport in accretion disks.

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Section: Radiating and Scattering Away Angular Momentummentioning

confidence: 99%

Section: Relatively Isotropic Emission With Internal Angular-momentummentioning

confidence: 99%

Liberation of Specific Angular Momentum Through Radiation and Scattering in Relativistic Black-Hole Accretion Disks

Stevens

2015

Publ. Astron. Soc. Aust.

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“…Subsequently, Chen and Taam and Wu et al got similar results, although some additional terms, such as causally limited viscosity [12] and radial viscous force [13], respectively, were included. After the anomalousviscosity model was presented in 2002, Yao and Li and Chen and Liu analyzed the instabilities of the accretion disk adopted the Li and Zhang's viscosity prescription by numerical simulations [14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

The radial–azimuthal instability of accretion disk with anomalous viscosity

Chen¹,

Jiang

2014

Can. J. Phys.

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The stability of the accretion disk is solved by numerical simulations when the radial and azimuthal perturbations are considered, where we adopt the anomalous viscosity model, which is close to real accretion disks. The results are discussed in the inner, intermediate, and outer regions of the accretion disk, respectively. With the increase of viscosity, ␣, the thermal mode and the viscous mode, as well as the acoustic modes, become more unstable in the disk dominated by radiation pressure (inner region). The instability is also influenced by the azimuthal perturbation wavenumber, n. With the increase of n, the thermal mode becomes more unstable, while the in-mode and out-mode become more stable no matter if the disk is dominated by radiation pressure or by gas pressure (intermediate and outer regions). There are many differences between our results and others' results, especially in the inner region of the disk, when the anomalous viscosity is considered. PACS Nos.: 97.10.Gz, 94.30.Gm, 66.20.+d, 52.35.Ra.Résumé : Nous solutionnons par simulation numérique le problème de stabilité du disque d'accrétion en tenant compte des perturbations radiales et azimutales, tout en adoptant un modèle anomal de viscosité qui est proche des vrais disques d'accrétion. Avec l'augmentation de la viscosité ␣, les modes thermique et visqueux, aussi bien que les modes acoustiques, deviennent plus instables dans le disque dominé par la pression de radiation (région interne). L'instabilité est aussi influencée par le nombre d'onde n de la perturbation azimutale. Sous l'augmentation de n, le mode thermique devient plus instable, alors que les modes in et out deviennent plus stables dans un disque dominé par la pression de radiation ou du gaz (région intermédiaire et région externe). Il y a plusieurs différences entre nos résultats et ceux d'autres auteurs, spécialement dans la région interne du disque où on envisage la viscosité anomale. [Traduit par la Rédaction]

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Anomalous magnetic viscosity in relativistic accretion disks

Cited by 2 publications

References 27 publications

Liberation of Specific Angular Momentum Through Radiation and Scattering in Relativistic Black-Hole Accretion Disks

Liberation of Specific Angular Momentum Through Radiation and Scattering in Relativistic Black-Hole Accretion Disks

The radial–azimuthal instability of accretion disk with anomalous viscosity

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