Anchoring Polar Magnetic Field in a Stationary Thick Accretion Disk

Abstract

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.

Accretion flows with comparable radiation and gas pressures

“…The important result of that work was to show that the accretion flows in advection-dominated regime tend to be quite thick. In our earlier studies (Samadi et al 2014 andAbbassi 2017), we focused on the effect of magnetic field with toroidal and poloidal configurations, separately. For both cases, the magnetic force acted in the opposite direction of the gas pressure force and made the disc thinner.…”