Maximal radiative efficiency of black-hole accretion
= Maximal radiative efficiency of black-hole accretion
{title2=$\eta_{\max}$}
The maximal radiative efficiency is the available binding energy per unit accreted rest-mass energy when all energy released outside the capture boundary escapes as radiation. A relativistic zero-torque disk has $\eta_{\max}=1-E_{\rm ISCO}$.