Transit time of black holes on generalized free energy landscape

A bstract Recently, the thermodynamics and kinetics of black hole phase transitions have garnered attention, particularly with the black hole radius being utilized as an order parameter within a generalized free energy landscape. In this framework, the local minima and maxima of the free energy correspond to stable and unstable states, respectively, while other states on the free energy landscape represent fluctuating black holes. Thermal fluctuations enable transitions between these stable states, and this stochastic kinetic behavior can be effectively described by the probabilistic Fokker-Planck equation. The transit time, defined as the time required for transitions or jumps between states, is a crucial physical quantity in phase transition kinetics, as it helps characterize the switching dynamics. By employing a harmonic transition state approximation, we examine the Hawking-Page phase transition and the Reissner-Nordström-Anti-de Sitter (RNAdS) black hole phase transition within the context of the generalized free energy landscape. We analytically quantify the transit time and its probability distribution for actual transition events, revealing the relationship between the mean transit time and the prefactor of the classical mean first passage time (MFPT). As the mean transit time decreases, the probability distribution narrows, indicating reduced fluctuations in transit time. These phenomena are connected to the topological structure of the generalized free energy landscape, the curvature of the free energy in both stable and unstable states, and the height of the energy barrier. We conclude that, for black hole phase transitions, the transit time serves as a characteristic timescale that reflects the actual jump time between states or to a transition state. Moreover, its relationship with the prefactor allows for a more precise quantification of the MFPT.