Viscous-resistive ADAF with a general large-scale magnetic field

Abbassi, Shahram; Mosallanezhad, Amin

doi:10.1007/s10509-012-1147-x

Cited by 8 publications

(4 citation statements)

References 29 publications

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“…Perhaps this result arises from considering a purely toroidal magnetic field. Although Abbassi & Mosallanezhad (2012) studied the effect of other field components on the dynamics of resistive ADAFs, the role of outflows was neglected in their work. In the present paper, we shall extend the work of Faghei & Mollatayefeh (2012) by considering other field components.…”

Section: Introductionmentioning

confidence: 99%

Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field

Ghoreyshi

2020

Publ. Astron. Soc. Aust.

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The observations and simulations have revealed that large-scale magnetic field and outflows can exist in the inner regions of an advection-dominated accretion disc where the resistive diffusion may also be important. In the present paper, the roles of large-scale magnetic field and outflows in the structure of resistive advection-dominated accretion discs are explored by assuming that the accretion flow is radially self-similar. In the non-ideal magnetohydrodynamic (MHD) approximation, the results show that the angular velocity is always sub-Keplerian when both the outflow and the large-scale magnetic field are taken into account. A stronger toroidal field component leads to faster rotation, while the disc rotates with faster rate if the vertical field component is weaker. The increase of magnetic diffusivity causes the infall velocity to be close to Keplerian velocity. Although the previous studies in the ideal MHD approximation have shown that the disc temperature decreases due to the vertical field component, we find that the effect of vertical field component on the temperature of a resistive disc depends on the magnetic diffusivity. When the magnetic diffusivity is high, the more efficient mechanism for decreasing the disc temperature can be the outflows, and not the large-scale magnetic field. In such a limit of the magnetic diffusivity, the components of the large-scale magnetic field enhance the gas temperature. The increase of temperature can lead to heating and acceleration of the electrons and help us to explain the origin of phenomena such as the flares in Sgr A*. On the other hand, the infall velocity in such a limit rises as the temperature increases, and therefore the surface density falls to too low values. Any change in the density profile can alter the structure and the emitted spectrum of disc.

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Section: Introductionmentioning

confidence: 99%

Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field

Ghoreyshi

2020

Publ. Astron. Soc. Aust.

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“…For example, Zahra Zeraatgari et al (2018) showed that the ohmic resistivity in such flows modifies the amount of magnetic field and the role of the magnetic field in transferring angular momentum. Abbassi and Mosallanezhad (2012) also showed that the rotational velocity of the resistive accretion flows in the absence of outflow depends on the magnetic diffusivity. They found that the effect of magnetic diffusivity on the rotational velocity depends on the field components (see also Ghoreyshi 2020).…”

Section: Introductionmentioning

confidence: 90%

“…Hence, we assume that the anomalous magnetic diffusivity η can be expressed in the same way as in Bisnovatyi-Kogan and Ruzmaikin (1976), namely, η = η 0 c s H, where the α-prescription of Shakura and Sunyaev (1973) is adopted and the magnetic diffusivity parameter η 0 is a constant, less than unity. Note that this form of the magnetic diffusivity was used in some previous work (e.g., Shadmehri 2004;Abbassi and Mosallanezhad 2012;Samadi et al 2014), although H was replaced by c s /Ω K in the definition of η.…”

Section: Basic Equationsmentioning

confidence: 99%

Resistive Hot Accretion Flows with Anisotropic Pressure

Ghoreyshi,

Khesali

2021

Preprint

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Since the collisional mean free path of charged particles in hot accretion flows can be significantly larger than the typical length-scale of the accretion flows, the gas pressure is anisotropic to magnetic field lines. For such a large collisional mean free path, the resistive dissipation can also play a key role in hot accretion flows. In this paper, we study the dynamics of resistive hot accretion flows in the presence of anisotropic pressure. We present a set of self-similar solutions where the flow variables are assumed to be a function only of radius. Our results show that the radial and rotational velocities and the sound speed increase considerably with the strength of anisotropic pressure. The increase in infall velocity and in sound speed are more significant if the resistive dissipation is taken into account. We find that such changes depend on the field strength. Our results indicate that the resistive heating is 10% of the heating by the work done by anisotropic pressure when the strength of anisotropic pressure is 0.1. This value becomes higher when the strength of anisotropic pressure reduces. The increase in disk temperature can lead to heating and acceleration of the electrons in such flows. It helps us to explain the origin of phenomena such as the flares in Galactic Center Sgr A*.

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“…Based on the self-similar assumption, many analytical works have also been done to investigate the structure and properties of hot accretion flow in one-dimension (e.g. Blandford & Begelman 1999;Akizuki & Fukue 2006;Abbassi et al 2008;Zhang & Dai 2008;Bu, Yuan & Xie 2009;Mosallanezhad et al 2012, Abbassi & Mosallanezhad 2012aMosallanezhad et al 2013) and also in two dimensions (e.g. Narayan & Yi 1995a;Xu & Chen 1997;Blandford & Begelman 2004;Xue & Wang 2005;Tanaka & Menou 2006;Jiao & Wu 2011;Mosallanezhad et al 2014;Samadi & Abbassi 2016;Mosallanezhad et al 2016;Samadi et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The effects of toroidal magnetic field on the vertical structure of hot accretion flows

Zeraatgari,

Mosallanezhad,

Abbassi

et al. 2017

Preprint

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We solved the set of two-dimensional magnetohydrodynamic (MHD) equations for optically thin black hole accretion flows incorporating toroidal component of magnetic field. Following global and local MHD simulations of black hole accretion disks, the magnetic field inside the disk is decomposed into a large scale field and a fluctuating field. The effects of the fluctuating magnetic field in transferring the angular momentum and dissipating the energy are described through the usual α description. We solved the MHD equations by assuming steady state and radially self-similar approximation in r − θ plane of spherical coordinate system. We found that as the amount of magnetic field at the equatorial plane increases, the heating by the viscosity decreases. In addition, the maximum amount of the heating by the viscous dissipation is produced at the mid-plane of the disk, while that of the heating by the magnetic field dissipation is produced at the surface of the disk. Our main conclusion is that in terms of the no-outflow solution, thermal equilibrium still exists for the strong magnetic filed at the equatorial plane of the disk.

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Viscous-resistive ADAF with a general large-scale magnetic field

Cited by 8 publications

References 29 publications

Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field

Self-similar structure of resistive ADAFs with outflow and large-scale magnetic field

Resistive Hot Accretion Flows with Anisotropic Pressure

The effects of toroidal magnetic field on the vertical structure of hot accretion flows

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