Black Hole Mechanics and Massive Gravity
Capela, Fabio (ULB)

We consider black hole mechanics in massive gravity. Using explicit black hole solutions, we discuss black hole merger processes in which i) total entropy of the system decreases ii) the zero-temperature extremal black hole is created. Thus, both second and third laws of thermodynamics are violated. In both cases, the violation can be traced back to the presence of negative-mass black holes, which, in turn, is related to the violation of the null energy condition. The violation of the third law of thermodynamics implies, in particular, that a naked singularity may be created as a result of the evolution of a singularity-free state. Wether the formation of negative-mass black holes can be forbidden dynamically will be discussed.