Dynamical horizon

In theoretical physics, a dynamical horizon (DH) is a local description (i.e. independent of the global structure of space–time) of evolving black-hole horizons. In the literature there exist two different mathematical formulations of DHs—the 2+2 formulation developed first by Sean Hayward and the 3+1 formulation developed by Abhay Ashtekar and others (see Ashtekar & Krishnan 2004). It provides a description of a black hole that is evolving (e.g. one that has a non-zero mass–energy influx). A related formalism, for black holes with zero influx, is an isolated horizon.