Hydrodynamical wind on magnetized Accretion Flows with Convection

TL;DR

This paper develops self-similar models of hot accretion flows around black holes, incorporating outflows, magnetic fields, and convection, revealing how these factors influence flow dynamics and structure.

Contribution

It introduces a comprehensive self-similar solution framework for RIAFs that includes magnetic fields, outflows, and convection, advancing understanding of their combined effects.

Findings

Magnetic fields increase surface density and rotational velocity.

Outflows reduce surface density and rotational velocity.

Outflows increase radial velocity, sound speed, and disc thickness.

Abstract

The existence of outflow and magnetic field in the inner region of hot accretion flows have been confirmed by observations and numerical magnetohydrodynamic simulations (MHD). We present self-similar solutions for radiation inefficiently accretion flows (RIAF) around black holes in the presence of outflow and global magnetic field. The influence of outflow is taken into account by adopting a radius dependent of mass accretion rate $ \dot{M} = \dot{M}_{0}(r/r_{0})^{s} $ with $ s > 0 $. Also we consider convection through a mixing length formalism to calculate convection parameter $ \alpha_{con} $. Moreover we consider the additional magnetic field parameters $ \beta_{r,\varphi,z}\big[= c^2_{r,\varphi,z}/(2 c^2_{s}) \big] $, where $ c^2_{r,\varphi,z} $ are the Alfv$\acute{e}$n sound speeds in three direction of cylindrical coordinate. Our numerical results show that by increasing all components of magnetic field, the surface density and rotational velocity increase although the sound speed and radial infall velocity of the disc decrease. Also we have found out that the existence of wind will lead to reduction of surface density as well as rotational velocity. Moreover the radial velocity, sound speed, advection parameter and the vertical thickness of the disc will increase when outflow becomes important in the radiation inefficiently accretion flow.