This region of twisted spacetime is called the ergosphere. It is impossible to stand still in this region.
(The term ergosphere comes from the Greek word for "work.") Astronomers think that a black hole powers its jets with energy from its spin.
Ergosphere is a surface of a static limit [g.sub.tt] = 0 given by
Each point of the ergosphere belongs to some of confocal ellipsoids (7) covering the whole space as the coordinate surfaces r = const.
In this process, all of the action takes place outside the black hole's event horizon, the boundary beyond which nothing can escape, in a flattened region called the ergosphere. Within the ergosphere, the black hole's rotation drags space-time along with it and everything is forced to move in the same direction at nearly speed of light.
The faster the black hole spins, the larger its ergosphere becomes, which allows high-energy collisions further from the event horizon.
It is conventionally alleged that the "region" between [r.sub.h] and [r.sub.b] is an ergosphere, in which spacetime is dragged in the direction of the of rotation of the point-charge.
The so-called ergosphere also arises from the aforesaid misconceptions.
For a thorough analysis of all these problems covering the ergosphere region of a Kerr black hole, Penrose process, particle collisions, and so on one must consult .
Let us add that "inverse" Compton process in the ergosphere of Kerr black hole was considered in  where the photon's energy showed increment due to rotational and curvature effects.
From (46) it is concluded that there exists no spacetime drag effect for the rotating point-mass and no ergosphere
Visser, "Acoustic black holes: horizons, ergospheres
and Hawking radiation," Classical and Quantum Gravity, vol.