Energetic processes around electromagnetically charged black hole in the Rastall gravity

Here we investigate the energetics of the charged-rotating-NUT-Kiselev black hole (CRNK-BH) in the Rastall modified theory of gravity. First, we study the dependence of the ergoregion around the CRNK-BH on the spacetime parameters, which is the key point to explain the energy extraction process from the BH. We show that the effect of the Kerr spin parameter a on this region is still dominating compared to the rest of the spacetime parameters. Then, we show that an increase in the NUT parameter l, electromagnetic charge q, and the parameter of equation-of-state of the quintessence !, increases the efficiency of the Penrose-process while the effect of the rest of the spacetime parameters is just opposite. Moreover, we study the energy extraction process from the CRNK-BH in the Rastall modified theory of gravity due to the Blandford-Znajek mechanism. We demonstrate that the effect of all the spacetime parameters, except the spin and NUT parameters, on the efficiency of the Blandford-Znajek process is similar to that of the Penrose-process. We also give a comparison of the two energy extracting processes, discussed here, for the CRNK-BH in the Rastall modified theory of gravity.