The Role of Outflows in dynamic of Advection Dominated Accretion Flows: a Self-Similar Solution

TL;DR

This paper presents a self-similar analytical model of advection-dominated accretion flows incorporating outflows, revealing how outflow parameters influence disc dynamics, temperature, and mass inflow rates.

Contribution

It introduces a self-similar solution framework for viscous accretion discs with outflows, linking outflow parameters to flow properties and the power-law index of mass inflow.

Findings

Outflow enhances the power index s of mass inflow rate.

Increased outflow parameter raises disc temperature and thickness.

Energy extraction by outflow decreases the power index s.

Abstract

The effects of outflow on the behavior of a viscous gaseous disc around a compact object in an advection-dominated state are examined in this paper. We suppose that the flow is steady, axisymmetric, and rotating. Also, we focus on the model in which the mass, the angular momentum, and the energy can be transported outward by outflow. Similar to the pioneering studies, we consider a power-law function for mass inflow rate as $\dot{M} \propto r^s$. We assume that the power index $s$ is proportional to the dimensionless thickness $H/R$ of disc. To analyze such a system, the hydrodynamic equations have extracted in cylindrical coordinates $(r,\varphi,z)$. Then, the flow equations were vertically integrated, and a set of self-similar solutions was got in the radial direction. Our solutions include three essential parameters: $\lambda$, $f$ and $\zeta$. The influence of the outflow on the dynamics of the disc is investigated by the $\lambda$ parameter. The degree of advection of flow is shown by the advection parameter $f$. Also, energy extraction from the disc by the outflow is showed by $\zeta$ parameter. Our findings demonstrate a significant correlation between the outflow parameters, flow advection parameter, and the temperature, thickness, and inflow-outflow rate of the disc. In addition, we explored the influence of these parameters on the power index $s$, too. The results of our study demonstrate that enhancing the outflow parameter or flow advection degree increases power index $s$, while extracting more energy through outflow decreases index $s$.