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A rotating black hole is a black hole that possesses angular momentum. In particular, it rotates about one of its axes of symmetry. All celestial objects – planets, stars , galaxies, black holes – spin. [1] [2] [3] The boundaries of a Kerr black hole relevant to astrophysics. Note that there are no physical "surfaces" as such.
The Kerr metric or Kerr geometry describes the geometry of empty spacetime around a rotating uncharged axially symmetric black hole with a quasispherical event horizon.The Kerr metric is an exact solution of the Einstein field equations of general relativity; these equations are highly non-linear, which makes exact solutions very difficult to find.
To account for charge, the metric must satisfy the Einstein field equations like before, as well as Maxwell's equations in a curved spacetime. A charged, non-rotating mass is described by the Reissner–Nordström metric. Rotating black holes are described by the Kerr metric (uncharged) and the Kerr–Newman metric (charged).
For a non-rotating black hole, this region takes the shape of a single point; for a rotating black hole it is smeared out to form a ring singularity that lies in the plane of rotation. [97] In both cases, the singular region has zero volume. It can also be shown that the singular region contains all the mass of the black hole solution. [98]
(Supermassive black holes up to 21 billion (2.1 × 10 10) M ☉ have been detected, such as NGC 4889.) [16] Unlike stellar mass black holes, supermassive black holes have comparatively low average densities. (Note that a (non-rotating) black hole is a spherical region in space that surrounds the singularity at its center; it is not the ...
The Penrose process (also called Penrose mechanism) is theorised by Sir Roger Penrose as a means whereby energy can be extracted from a rotating black hole. [1] [2] [3] The process takes advantage of the ergosphere – a region of spacetime around the black hole dragged by its rotation faster than the speed of light, meaning that from the point of view of an outside observer any matter inside ...
Roy P. Kerr CNZM FRS FRSNZ Kerr in 2024 Born (1934-05-16) 16 May 1934 (age 90) Kurow, New Zealand Nationality New Zealand Education St. Andrew's College, Christchurch Alma mater University of New Zealand (BSc) University of Cambridge (PhD) Known for Kerr metric Kerr–Newman metric Kerr–Schild perturbations Awards Hector Medal (1982) Hughes Medal (1984) Rutherford Medal (1993) Albert ...
Ergosphere – region located outside a rotating black hole. Hawking radiation – black-body radiation that is predicted to be emitted by black holes, due to quantum effects near the event horizon. [2] Penrose process – process theorised by Roger Penrose wherein energy can be extracted from a rotating black hole.