Estimation of the mass outflow rates from viscous accretion discs

TL;DR

This paper investigates viscous accretion discs around black holes, analyzing shock formation, outflow rates, and the effects of viscosity and dissipation on accretion dynamics and outflow properties.

Contribution

It provides a detailed analysis of shock conditions, outflow rates, and the influence of viscosity and dissipation in viscous accretion discs around black holes.

Findings

Stationary shocks occur within specific viscosity parameter ranges.

Mass outflow rate is typically 5-10% of inflow rate.

Increased viscosity reduces shock location and outflow rate.

Abstract

We study viscous accretion disc around black holes, and all possible accretion solutions, including shocked as well as shock free accretion branches. Shock driven bipolar outflows from a viscous accretion disc around a black hole has been investigated. One can identify two critical viscosity parameters $\alpha_{cl}$ and $\alpha_{cu}$, within which the stationary shocks may occur, for each set of boundary conditions. Adiabatic shock has been found for upto viscosity parameter $\alpha=0.3$, while in presence of dissipation and massloss we have found stationary shock upto $\alpha=0.15$. The mass outflow rate may increase or decrease with the change in disc parameters, and is usually around few to 10% of the mass inflow rate. We show that for the same outer boundary condition, the shock front decreases to a smaller distance with the increase of $\alpha$. We also show that the increase in dissipation reduces the thermal driving in the post-shock disc, and hence the mass outflow rate decreases upto a few %.