Thermodynamics and weak cosmic censorship conjecture of charged AdS black hole in the Rastall gravity with pressure**Project supported by the National Natural Science Foundation of China (Grant Nos. 11875095 and 11903025), the Basic Research Project of Science and Technology Committee of Chongqing (Grant No. cstc2018jcyjA2480), and the Fundamental Research Funds of ChinaWest Normal University (Grant No. 18Q062).

Abstract

Treating the cosmological constant as a dynamical variable, we investigate the thermodynamics and weak cosmic censorship conjecture (WCCC) of a charged AdS black hole (BH) in the Rastall gravity. We determine the energy momentum relation of charged fermion at the horizon of the BH using the Dirac equation. Based on this relation, it is shown that the first law of thermodynamics still holds as a fermion is absorbed by the BH. However, the entropy of both the extremal and near-extremal BH decreases in the irreversible process, which means that the second law of thermodynamics is violated. Furthermore, we verify the validity of the WCCC by the minimum values of the metric function h(r) at its final state. For the extremal charged AdS BH in the Rastall gravity, we find that the WCCC is always valid since the BH is extreme. While for the case of near-extremal BH, we find that the WCCC could be violable in the extended phase space (EPS), depending on the value of the parameters of the BH and their variations.