Mechanics of isolated horizons

A set of boundary conditions defining an undistorted, non-rotating isolated horizon are specified in general relativity. A spacetime representing a black hole which is itself in equilibrium but whose exterior contains radiation admits such a horizon. However, the definition is applicable in a more general context, such as cosmological horizons. Physically motivated, (quasi-)local definitions of the mass and surface gravity of an isolated horizon are introduced and their properties analysed. Although their definitions do not refer to infinity, these quantities assume their standard values in the static black-hole solutions. Finally, using these definitions, the zeroth and first laws of black-hole mechanics are established for isolated horizons.