EQUILIBRIUM 2-DIMENSIONAL DILATONIC SPACETIMES

We study two-dimensional dilaton gravity coupled to massless scalar fields and look for time-independent solutions. In addition to the well-known black hole, we find another class of solutions that may be understood as the black hole in equilibrium with a radiation bath. We claim that there is a solution that is qualitatively unchanged after including Hawking radiation and back reaction and is geodesically complete. We compute the thermodynamics of these spacetimes and their mass. We end with a brief discussion of the linear response about these solutions, its significance to stability and noise, and speculation regarding the end point of Hawking evaporation in four dimensions.