Advection-Dominated Accretion Disks: Geometrically Slim or Thick?

Gu, Wei‐Min; Xue, L.; Liu, Tong; Lu, Jing

doi:10.1093/pasj/61.6.1313

Cited by 30 publications

(49 citation statements)

References 32 publications

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“…Following Gu et al 2009, we neglected the meridional velocity (v θ ) and assumed the dominant component of stress tensor is T rφ . Unlike Gu et al 2009, we didn't need to employ the well-known polytropic relation of p = Kρ γ in the θ-direction.…”

Section: Discussionmentioning

confidence: 99%

“…In order to study the possible effect of poloidal magnetic field on the accretion system, we follow Gu et al 2009 and assume v θ = 0 which provides more accuracy in the spherical coordinates in comparison with accuracy of considering v z = 0 in the cylindrical coordinates. On the other hand, in the spherical coordinate we do not need to use heightaveraged quantities which is less reliable in thick disks.…”

Section: Equationsmentioning

confidence: 99%

“…The flow in their work was assumed to fill the whole space between the two poles, hence the concept of disk and its thickness were not meaningful in that case. Gu et al (2009) investigated the proper condition for advection dominance and found out the half-thickness of the disk must be greater than 72…”

Section: Introductionmentioning

confidence: 99%

“…One of our purposes here is to determine the advection parameter with respect to polar angle. Narayan & Yi 1994, 1995a,b assume that f is constant for the whole of the flow whereas Gu et al 2009 solve the ODE's set and then with using energy equation, they find angular profile of f . We follow the same way to obtain advection parameter versus polar angle.…”

Section: Introductionmentioning

confidence: 99%

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Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

Samadi

Abbassi

2017

ApJ

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We investigate the properties of a hot accretion flow bathed in a poloidal magnetic field. We consider an axisymmetric viscous resistive flow in the steady state configuration. We assume the dominant mechanism of energy dissipation is due to turbulence viscosity and magnetic diffusivity. A certain fraction of that energy can be advected towards the central compact object. We employ self-similar method in the radial direction to find a system of ODEs with just one varible, θ in the spherical coordinates. For the existence and maintaining of a purely poloidal magnetic in a rotating thick disk, we find the necessary condition is a constant value of angular velocity along a magnetic field line. We obtain an analytical solution for the poloidal magnetic flux. We explore possible changes in the vertical structure of the disk under the influences of even symmetric and asymmetric magnetic fields. Our results reveal that a polar magnetic field with even symmetry about the equatorial plane makes the disk vertically thin. Moreover, the accretion rate decreases when we consider a strong magnetic field. Finally, we notice hot magnetized accretion flows can be fully advected even in a slim shape.

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Section: Discussionmentioning

confidence: 99%

Section: Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

Samadi

Abbassi

2017

ApJ

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“…As a consequence, the inner disk will be invisible to an observer with an inclination angle of  q  25 . On the other hand, some analytical works also pointed out that the superEddington accretion disk, which is optically thick and probably advection dominated, is likely to be geometrically thick rather than slim if the gravitational force of the central black hole is well treated (Gu & Lu 2007;Gu et al 2009;Gu 2012).…”

Section: Thick Disk Modelmentioning

confidence: 99%

Thick Accretion Disk Model for Ultraluminous Supersoft Sources

Yuan

et al. 2016

ApJL

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We propose a geometrically thick, super-Eddington accretion disk model, where an optically thick wind is not necessary, to understand ultraluminous supersoft sources (ULSs). For high mass accretion ratesis the Eddington accretion rate, the hard photons from the hot inner region may be shaded by the geometrically thick inner disk, and therefore only the soft photons from the outer thin disk and the outer photosphere of the thick disk can reach the observer. Our model can naturally explain the approximate relation between the typical thermal radius and the thermal temperature, µ -R T bb bb 2 . Moreover, the thick disk model can unify ULSs and normal ultraluminous X-ray sources, where the different observational characteristics are probably related to the inclination angle and the mass accretion rate. By comparing our model with the optically thick outflow model, we find that a lower mass accretion rate is required in our model.

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Revisiting vertical structure of neutrino-dominated accretion disks: Bernoulli parameter, neutrino trapping and other distributions

Liu¹,

Gu²,

Xue³

et al. 2011

Astrophys Space Sci

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We revisit the vertical structure of neutrinodominated accretion flows (NDAFs) in spherical coordinates with a new boundary condition based on the mechanical equilibrium. The solutions show that NDAF is significantly thick. The Bernoulli parameter and neutrino trapping are determined by the mass accretion rate and the viscosity parameter. According to the distribution of the Bernoulli parameter, the possible outflow may appear in the outer region of the disk. The neutrino trapping can essentially affect the neutrino radiation luminosity. The vertical structure of NDAF is like a "sandwich", and the multilayer accretion may account for the flares in gamma-ray bursts.

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Advection-Dominated Accretion Disks: Geometrically Slim or Thick?

Cited by 30 publications

References 32 publications

Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

Thick Accretion Disk Model for Ultraluminous Supersoft Sources

Revisiting vertical structure of neutrino-dominated accretion disks: Bernoulli parameter, neutrino trapping and other distributions

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