Maximal Efficiency of Collisional Penrose Process with Spinning Particle II

We analyze the collisional Penrose process between a particle on the ISCO orbit around an extreme Kerr black hole and a particle impinging from infinity. We consider both cases with non-spinning and spinning particles. We evaluate the maximal efficiency, $\eta_{$\text{max}$}=(\text{extracted energy})/($\text{input energy}$)$, for the elastic collision of two massive particles and for the photoemission process, in which the ISCO particle will escape to infinity after the collision with a massless impinging particle. For non-spinning particles, the maximum efficiency is $\eta_{$\text{max}$} \approx 2.562$fortheelasticcollisionand$\eta_{$\text{max}$} \approx 7$ for the photoemission process. While for spinning particles we obtain the maximal efficiency ${\eta }_{\text{max}}\approx 8.442$ for the elastic collision and ${\eta }_{\text{max}}\approx 12.54$ for the photoemission process.