Advection‐dominated Accretion Flows in the Kerr Metric. II. Steady State Global Solutions

Abstract

In a previous paper we have written down equations describing steady-state, optically thin, advection-dominated accretion onto a Kerr black hole (Gammie and Popham 1997, hereafter Paper I). In this paper we survey the numerical solutions to these equations. We find that the temperature and density of the gas in the inner part of the accretion flow depend strongly on the black hole spin parameter $a$. The rate of angular momentum accretion is also shown to depend on $a$; for $a$ greater than an equilibrium spin parameter $a_{eq}$ the black hole is de-spun by the accretion flow. We also investigate the dependence of the flow on the angular momentum transport efficiency $\alpha$, the advected fraction of the dissipated energy $f$, and the adiabatic index $\gamma$. We find solutions for $-1 < a < 1$, $10^{-4} \le \alpha \le 0.44$, $0.01 \le f \le 1$, and $4/3 < \gamma < 5/3$. For low values of $\alpha$ and $f$ the inner part of the flow exhibits a pressure maximum and appears similar to equilibrium thick disk solutions.