Effect of the flow composition on outflow rates from accretion discs around black holes

Abstract

We studied the outflow behaviour from accretion discs around black holes taking into account the vertical equilibrium accretion flow model. The outflow rate is found to depend crucially on flow composition. Our approach is to study the outflow behaviour as function of inflow around black holes with an equation of state which allows flow to be thermally relativistic close to black holes and non-relativistic far away from black holes.We studied shock ejection model. A pure electron-positron pair flow never undergoes shock transition while presence of some baryons (common in outflows and jets) makes it possible to have standing shock waves in the flow. It can be concluded that the presence of protons is necessary for the flow to show the outflow behaviour. The outflow rate is maximum when the flow contains the proton number density which is 27 per cent of the electron number density. We conclude that a pure electron-positron jet is unlikely to form. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.