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A rotating black hole (Kerr black hole or Kerr-Newman black hole) is a black hole that possesses angular momentum. It is one of three possible types of black holes that could exist in the theory of gravitation called General Relativity. Black holes can be characterized by three (and only three) quantities M, J and Q, namely: An artists impression of a black hole with a closely orbiting companion star that exceeds its Roche limit. ...
In physics, angular momentum intuitively measures how much the linear momentum is directed around a certain point called the origin; the moment of momentum. ...
Two-dimensional visualisation of space-time distortion. ...
Rotating black holes are thought to be formed in the gravitational collapse of a massive rotating star or from the collapse of a collection of stars with an average non-zero angular momentum. Most stars rotate and therefore it is expected that most black holes in nature are rotating black holes. Rotating black holes can produce large amounts of energy at the expense of its rotational energy. In that case a rotating black hole gradually reduces to a Schwarzschild black hole, the minimum configuration from which no further energy can be extracted. The formation of a rotating black hole is thought to be observed as the emission of gamma ray bursts. Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ...
A Schwarzschild black hole or static black hole is a black hole fully defined by its only parameter, the mass M. In general black holes could have in addition angular momentum (rotating black holes) and electric charge (see charged black holes). ...
In physics, angular momentum intuitively measures how much the linear momentum is directed around a certain point called the origin; the moment of momentum. ...
Electric charge is a fundamental property of some subatomic particles, which determines their electromagnetic interactions. ...
Gravitational collapse in astronomy is the sudden inward fall of a massive body under the influence of the force of gravity. ...
For alternate meanings see star (disambiguation) Hundreds of stars are visible in this image taken by the Hubble Space Telescope of the Sagittarius Star Cloud in the Milky Way Galaxy. ...
In astronomy, gamma-ray bursts (GRBs) are flashes of gamma rays that last from seconds to hours, the longer ones being followed by several days of X-ray afterglow. ...
Ergosphere and the Penrose process A black hole in general is surrounded by a spherical surface, the event horizon situated at the Schwarzschild radius, where the escape velocity is equal to the velocity of light. Within this surface, no observer/particle can maintain itself at a constant radius. It is forced to fall inwards, and so this is sometimes called the static limit. This article is on the film Event Horizon. ...
The Schwarzschild radius or gravitational radius is a characteristic radius associated with every mass. ...
 Two important surfaces around a rotating black hole. The inner sphere is the static limit (the event horizon). It is the inner boundary of a region called the ergosphere. The oval-shaped surface, touching the event horizon at the poles, is the outer boundary of the ergosphere. Within the ergosphere a particle is forced (dragging of space and time) to rotate and may gain energy at the cost of the rotational energy of the black hole (Penrose-process). A rotating black hole has the same static limit at the Schwarzschild radius but there is an additional surface outside the Schwarzschild radius named the Killing horizon, given by (r − GM)2 = G2M2 − J2cos2θ in Boyer-Lindquist coordinates, which can be intuitively characterized as the sphere where "the rotational velocity of the surrounding space" is dragged along with the velocity of light. Within this sphere the dragging is greater than the speed of light. So, within this sphere, no observer/particle can maintain itself in a non-rotating orbit, but is forced to become co-rotated.
The region outside the event horizon but inside the sphere where the rotational velocity is the speed of light, is called the ergosphere (from Greek ergon meaning work). Particles falling within the ergosphere are forced to rotate faster and thereby gain energy. Because they are still outside the event horizon, they may escape the black hole. The net process is that the rotating black hole emits energetic particles at the cost of its own total energy. The possibility of extracting spin energy from a rotating black hole was first proposed by the mathematician Roger Penrose in 1969 and is thus called the Penrose process. Rotating black holes in astrophysics are a potential source of large amounts of energy and are used to explain energetic phenomena, such as gamma ray bursts. Sir Roger Penrose OM (born August 8, 1931) is an English mathematical physicist. ...
1969 was a common year starting on Wednesday (the link is to a full 1969 calendar). ...
In astronomy, gamma-ray bursts (GRBs) are flashes of gamma rays that last from seconds to hours, the longer ones being followed by several days of X-ray afterglow. ...
Two event horizons A rotating black hole is very different from a Schwarzschild black hole in that the spin of the black hole will cause the creation of two event horizons, an inner one and an outer one. As the spin increases, the inner event horizon moves outward, and the outer one moves inward. If the spin is great enough, the two will eventually merge and shrink towards the singularity. With no event horizons to hide it from the rest of the universe, the black hole ceases to be a black hole and will instead be a naked singularity. A Schwarzschild black hole or static black hole is a black hole fully defined by its only parameter, the mass M. In general black holes could have in addition angular momentum (rotating black holes) and electric charge (see charged black holes). ...
This article is on the film Event Horizon. ...
Singularity has several different meanings: mathematical singularity - a point where a mathematical function goes to infinity or is in certain other ways ill-behaved gravitational singularity - an infinity occurring in an astrophysical model, involving infinite curvature (a mathematical singularity) in the space/time continuum technological singularity - a predicted point in...
In general relativity, a naked singularity is a gravitational singularity without an event horizon. ...
Due to the two event horizons, a rotating black hole is also required to have two photon spheres, an inner and an outer one. The greater the spin of the black holes is, the farther from each other the photon spheres move. A beam of light travelling in a direction opposite to the spin of the black hole will be caught in the outer photon sphere. A beam of light travelling in the same direction as the black hole's spin will caught in the inner photon sphere.
Kerr metric, Kerr-Newman metric A rotating black hole is a solution of Einstein's field equation. This solution, the metric of spacetime associated with a point mass containing angular momentum and vacuum outside, was obtained by Roy Kerr in 1963 and is called the Kerr metric. In 1965 Ezra Newman found the solution for Einstein's field equation for a black hole which is both rotating and electrically charged. It is called the Kerr-Newman metric . A black hole with charge and spin has the same gyromagnetic ratio as an electron. Its magnetic moment divided by angular momentum is equal to its charge divided by mass. For other topics related to Einstein see Einstein (disambig) Introduction In physics, the Einstein field equation or Einstein equation is a tensor equation in the theory of gravitation. ...
In physics, he Kerr metric describes the geometry of spacetime around a rotating black hole. ...
The Kerr-Newman metric is a solution of Einsteins field equations that describes the spacetime geometry around a charged (), rotating () black hole of mass m. ...
Spinning black holes as wormholes  A Penrose diagram for a spinning black hole: an object travelling on worldline B can emerge out of the spinning black hole. Because of its two event horizons, it might be possible to avoid hitting the singularity of a spinning black hole. At the outer event horizon, the properties of spacetime allow objects to move only towards the singularity. However, when an object passes the inner event horizon, the object is able to move in directions away from the singularity, pass through another set of inner and outer event horizons, and emerge out of the black hole into another universe or another part of this universe without traveling faster than the speed of light (following a time-like path). A wormhole, also known as an Einstein-Rosen bridge, is a hypothetical topological feature of spacetime that is essentially a shortcut from one point in the universe to another point in the universe, allowing travel between them that is faster than it would take light to make the journey through...
In special relativity and general relativity, time and three-dimensional space are treated together as a single four-dimensional pseudo-Riemannian manifold called spacetime. ...
The deepest visible-light image of the cosmos. ...
Cherenkov effect in a swimming pool nuclear reactor. ...
In the context of special relativity, time-like separated points (or events) in spacetime have a spacetime interval greater than 0 (see sign convention). ...
See also Black holes by type: An artists impression of a black hole with a closely orbiting companion star that exceeds its Roche limit. ...
Black holes by mass: A Schwarzschild black hole or static black hole is a black hole fully defined by its only parameter, the mass M. In general black holes could have in addition angular momentum (rotating black holes) and electric charge (see charged black holes). ...
A charged black hole is a black hole that possesses electric charge. ...
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