The role of radial viscosity force and anisotropic thermal conduction in hot accretion flow

Abstract

Recent observational evidence confirms the weak-collision dynamics of hot optically thin accretion flows around Sgr A${}^{\ast }$ and other nearby galactic nuclei. As a result, thermal conduction as a diffusion process can transfer the heat by electrons in a collisionless magnetized plasma. While most of the previous analytical studies consider the azimuthal viscosity, the recent studies indicated that the radial viscosity strongly affects the properties of the advection dominated accretion discs. So, in this paper, we explore the roles of two parts of anisotropic thermal conduction (parallel and perpendicular) and radial viscosity in the hot accretion disc by considering axisymmetric and steady state assumptions in the presence of outflows that can transport energy from accretion disc outward. We use the set of self-similar solutions to solve the basic equations in our present model. Our solutions reveal that transverse thermal conduction as a cooling mechanism, leads to reductions in gas temperature, disc thickness, and accretion velocity of the disc, whereas the disc rotates at a fast rate. Moreover Our solutions indicate that the perpendicular thermal conduction and the radial viscosity have opposite behavior in the physical variables of the disc. Also, our results have indicated that the anisotropic thermal conduction is significant in the parameter space of radial viscosity, outflow in the regions that the physical constraints $t_{in}\ge t_{\perp ,con}$ and $q_{\parallel ,con}⩽q_{\perp ,con}$ are satisfied.