Self-similar solutions of viscous–resistive advection-dominated accretion flows with poloidal magnetic fields

Ghanbari, Jamshid; Salehi, Fatemeh; Abbassi, Shahram

doi:10.1111/j.1365-2966.2007.12216.x

Cited by 24 publications

(36 citation statements)

References 22 publications

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“…This powerful technique is self-similar method, a dimensional analysis and scaling law as a common tool in astrophysical fluid mechanics. Following NY95a and the other similar works (Ghanbari et al 2007, Samadi et al 2014, self-similarity in the radial direction is assumed, so the velocity components are proportional to r −1/2 and while for the density ρ ∝ r −n , therefore gas and magnetic pressure must be (p, B 2 i ) ∝ r −n−1 . Knowing radius dependency of the magnetic pressure leads us to find,…”

Section: Self-similar Solutionsmentioning

confidence: 99%

The effect of large-scale magnetic field on outflow in ADAFs: an odd symmetry configuration

Samadi

Abbassi

2015

Mon. Not. R. Astron. Soc.

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We construct self-similar inflow-outflow solutions for a hot viscous-resistive accretion flow with large scale magnetic fields that have odd symmetry with respect to the equatorial plane in B θ , and even symmetry in B r and B φ . Following previous authors, we also assume that the polar velocity v θ is nonzero. We focus on four parameters: β r0 , β φ0 (the plasma beta parameters for associated with magnetic field components at the equatorial plane), the magnetic resistivity η 0 , and the density index n = −d ln ρ/d ln r. The resulting flow solutions are divided into two parts consisting of an inflow region with a negative radial velocity (v r < 0) and an outflow region with v r > 0. Our results show that stronger outflows emerge for smaller β r0 ( 10 −2 for n > 1) and larger values of β φ0 , η 0 and n.

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Section: Self-similar Solutionsmentioning

confidence: 99%

The effect of large-scale magnetic field on outflow in ADAFs: an odd symmetry configuration

Samadi

Abbassi

2015

Mon. Not. R. Astron. Soc.

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“…However, recent works represent importance of magnetic diffusivity in accretion discs (e.g. Kuwabara et al 2000;Kaburaki 2000 ;Kaburaki et al 2002;Sh04;Ghanbari et al 2007;Krasnopolsky et al 2010;Kaburaki et al 2010). Sh04 studied a quasi-spherical accretion flow that dominant mechanism of energy dissipation was assumed to be the magnetic diffusivity due to turbulence in the accretion flow and the viscosity of the fluid was completely neglected.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, the role of the magnetic fields on ADAFs has been analyzed in detail by a number of investigators (Bisnovatyi-kogan & Lovelace 2001;Akizuki & Fukue 2006, hereafter AF06;Shadmehri 2004, hereafter Sh04; Ghanbari et al, 2007;Bu, Yung, & Xie 2009;Khesali & Faghei 2009, hereafter KF09). The existence of the toroidal magnetic field has been proven in the outer regions of the discs of young stellar objects (YSOs; Aitken et al 1993;Wright et al 1993) and in the Galactic center Chuss et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Self-Similar Solutions for Viscous and Resistive Advection Dominated Accretion Flows

Faghei

2012

J Astrophys Astron

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Abstract.In this paper, the self-similar solution of resistive advection dominated accretion flows (ADAF) in the presence of a pure azimuthal magnetic field is investigated. The mechanism of energy dissipation is assumed to be the viscosity and the magnetic diffusivity due to turbulence in the accretion flow. It is assumed that the magnetic diffusivity and the kinematic viscosity are not constant and vary by position and α-prescription is used for them. In order to solve the integrated equations that govern the behavior of the accretion flow, a self-similar method is used. The solutions show that the structure of accretion flow depends on the magnetic field and the magnetic diffusivity. As, the radial infall velocity and the temperature of the flow increase, and the rotational velocity decreases. Also, the rotational velocity for all selected values of magnetic diffusivity and magnetic field is sub-Keplerian. The solutions show that there is a certain amount of magnetic field that the rotational velocity of the flow becomes zero. This amount of the magnetic field depends on the gas properties of the disc, such as adiabatic index and viscosity, magnetic diffusivity, and advection parameters. The solutions show the mass accretion rate increases by adding the magnetic diffusivity and in high magnetic pressure case, the ratio of the mass accretion rate to the Bondi accretion rate decreases as magnetic field increases. Also, the study of Lundquist and magnetic Reynolds numbers based on resistivity indicates that the linear growth of magnetorotational instability (MRI) of the flow decreases by resistivity. This property is qualitatively consistent with resistive magnetohydrodynamics (MHD) simulations.

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“…Following NY95a and the other similar works (Ghanbari et al 2007, self-similarity in the radial direction is employed, so all types of velocities become proportional to r −1/2 and for density we can write, ρ ∝ r −n . If we use v r (r, θ) = v r (θ)r −1/2 and ρ(r, θ) = ρ(θ)r −n in the continuity equation (1), we will have:…”

Section: Self-similar Solutionsmentioning

confidence: 99%

“…Some of them (e.g. Shadmehri 2004, Ghanbari et al 2007, Shaghaghian 2011, 2016) studied purely poloidal magnetic fields and many concentrated only toroidal fields (Akizuki & Fukue 2006, Khesali & Faghei 2008, Mosallanezhad et al 2014, 2016, Sarkar & Das 2016) and a few theoritical works have been recently done with the global magnetic field (Samadi & Abbassi 2016, Mosallanezhad et al 2016, Samadi et al 2017.…”

Section: Introductionmentioning

confidence: 99%

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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Self-similar solutions of viscous–resistive advection-dominated accretion flows with poloidal magnetic fields

Cited by 24 publications

References 22 publications

The effect of large-scale magnetic field on outflow in ADAFs: an odd symmetry configuration

The effect of large-scale magnetic field on outflow in ADAFs: an odd symmetry configuration

Self-Similar Solutions for Viscous and Resistive Advection Dominated Accretion Flows

Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

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