Black-hole thermodynamics for the nonstationary case

Abstract

The attempt of nonstationary black-hole thermodynamics is made for the case of radiation mode of Vaidya metric. Calculating the modified temperature from the wave equation, entropy is defined by the apparent horizon, as the local quantity whose state is a proper fiducial equilibrium state. In those thermodynamic quantities we try to see what the mass-varying effects play the role of. So it is a kind of quasi-equilibrium thermodynamic theory on the two points of view for mass-varying processes, rather than a complete nonequilibrium thermodynamics. © 1990 Società Italiana di Fisica.