The influence of large-scale magnetic field in the structure of supercritical accretion flow with outflow

Abstract

We present the effects of ordered large scale magnetic field on the structure of supercritical accretion flow in the presence of outflow. In the cylindrical coordinates (r, ϕ, z), We write the 1.5 dimensional, the steady state ( ∂ ∂t = 0) and axisymmetric ( ∂ ∂ϕ = 0) inflow-outflow equations by using the self similar solutions. Also a model for radiation pressure supported accretion flow threaded by both toroidal and vertical components of magnetic field has been formulated. For studying the outflows, we adopt a radius dependent mass accretion rate aṡ M =Ṁ out ( . Also by following the previous works, we have considered the interchange of mass, radial and angular momentum and the energy between inflow and outflow. we have found numerically that two components of magnetic field have the opposite effects on the thickness of the disc and similar effects on the radial and angular velocities of the flow. We have found that the existence of the toroidal component of magnetic field will lead to increasing of radial and azimuthal velocities as well as the relative thickness of the disc, which is increased . Moreover, the thickness of the disc will decrease when the vertical component of magnetic field becomes important in magnetized flow. The solutions indicated that the mass inflow rate, the specific energy of outflow affect strongly on the advection parameter.We have shown that by increasing the two components of magnetic field, the temperature of the accretion flow will decrease significantly. On the other hand we have shown the bolometric luminosity of the slim discs for high values ofṁ(ṁ >> 1) is not sensitive to mass accretion rate and is kept constant (L ≈ 10L E ).

The self-similar structure of advection-dominated discs with outflow and radial viscosity

“…Using self-similar solutions, the dynamical properties of the advection-dominated discs in the presence of outflows have been widely studied during recent years. Many authors studied properties of these discs in the presence of various physical ingredients like the magnetiec fields (e.g., Bu et al 2009;Ghasemnezhad & Abbassi 2017), magnetic diffusion (e.g., Faghei & Mollatayefeh 2012, self-gravity (e.g., Shadmehri 2009;Abbassi et al 2013;Ghasemnezhad & Abbassi 2016), radial viscous force (e.g., Beckert 2000), thermal conduction (e.g., Shadmehri 2008), and convection (e.g., Ghasemnezhad 2017). These studies led to interesting results.…”

The role of anisotropic thermal conduction in a collisionless magnetized hot accretion flow

“…We can write the 1.5 dimensional MHD equations of our system (the conservation of mass, momentum and energy) by considering of the effects of anisotropic thermal conduction, outflow, and magnetic field by following the Bu et al (2009) and Ghasemnezhad (2017) in the cylindrical coordinates (r, ,z) by using the self simillar solutions, the technique and assumptions of Bu et al (2009). The perpendicular thermal conduction timescale and the local infall timescale can be stated respectively as:…”

“…By substituting the self-similar solutions(Bu et al 2009, Akizuki & Fukue 2006, Ghasemnezhad 2017) and by using the inverse rotation frequency at the outer radius of the disc, is the ratio of azimuthal magnetic pressure to gas pressure, , are the perpendicular conduction viscosity and kinematic viscosity coefficient and 3 , 1 are the dimensionless velocities of inflow. So the ratio of the parallel component of thermal conduction to its perpendicular component is as follows: above self-similar solutions into this relation, this ratio can be obtained: , are the parallel conduction coefficient and wind parameter.…”

Self-Similar Solution of Hot Accretion Flow with Anisotropic Pressure

“…Recently, numerical simulations found that strong outflow can be launched in hot accretion flows (e.g., Yuan et al [23,24]; Narayan et al [25]; Li et al [26]; Bu et al [27]; Bu et al [28,29]). The properties of outflow from hot accretion flows have also been studied by analytical works (Xue and Wang [30]; Akizuki and Fukue [31]; Bu et al [32]; Li and Cao [33]; Jiao and Wu [34]; Begelman [35]; Wu et al [36]; Gu [37]; Cao [38]; Ghasemnezhad and Abbassi [39]; Kumar and Gu [40]). Observations of low-luminosity active galactic nuclei and a hard state of black hole X-ray binaries showed indirect evidence that strong outflow can be launched in hot accretion flows (e.g., Crenshaw and Kraemer [41]; Cheung et al [42]; Homan et al [43]; Ma et al [44]; Park et al [45]).…”