A charged black hole is a
black hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...
that possesses
electric charge. Since the electromagnetic repulsion in compressing an electrically charged mass is dramatically greater than the gravitational attraction (by about 40 orders of magnitude), it is not expected that black holes with a significant electric charge will be formed in nature.
Categories
The two types of charged black holes are
Reissner–Nordström black holes (without spin) and
Kerr–Newman black holes (with spin).
A black hole can be completely characterized by three (
and only three) quantities:
* ''M'' –
mass
* ''J'' –
angular momentum
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed syste ...
* ''Q'' –
electric charge
Charged black holes are two of four possible types of black holes that have been found by solving Einstein's theory of gravitation,
general relativity. The mathematical solutions for the shape of space and the electric and magnetic fields near a black hole are named after the persons who first worked them out. The solutions increase in complexity depending on which of the two parameters, ''J'' and ''Q'', are zero (or not) (the mass ''M'' of a black hole could conceivably be tiny, but not zero). The four categories of solutions are given in the table below:
The solutions of
Einstein's field equation
In the general theory of relativity, the Einstein field equations (EFE; also known as Einstein's equations) relate the geometry of spacetime to the distribution of matter within it.
The equations were published by Einstein in 1915 in the for ...
for the
gravitational field of an electrically charged point mass (with zero angular momentum) in empty space was obtained in 1918 by
Hans Reissner
Hans Jacob Reissner, also known as Jacob Johannes Reissner (18 January 1874, Berlin – 2 October 1967, Mt. Angel, Oregon), was a German aeronautical engineer whose avocation was mathematical physics. During World War I he was awarded the Iron ...
and
Gunnar Nordström, not long after
Karl Schwarzschild
Karl Schwarzschild (; 9 October 1873 – 11 May 1916) was a German physicist and astronomer.
Schwarzschild provided the first exact solution to the Einstein field equations of general relativity, for the limited case of a single spherical non-r ...
found the
Schwarzschild metric
In Einstein's theory of general relativity, the Schwarzschild metric (also known as the Schwarzschild solution) is an
exact solution to the Einstein field equations that describes the gravitational field outside a spherical mass, on the assumpti ...
as a solution for a point mass without electric charge and angular momentum.
A mathematically-oriented article describes the
Reissner–Nordström metric
In physics and astronomy, the Reissner–Nordström metric is a static solution to the Einstein–Maxwell field equations, which corresponds to the gravitational field of a charged, non-rotating, spherically symmetric body of mass ''M''. ...
for a charged, non-rotating black hole. A similarly technical article on the
Kerr–Newman black hole gives an overview of the most general known solution for a black hole, which has both angular momentum and charge (all the other solutions are simplified special cases of the
Kerr–Newman black hole).
See also
*
Reissner–Nordström metric
In physics and astronomy, the Reissner–Nordström metric is a static solution to the Einstein–Maxwell field equations, which corresponds to the gravitational field of a charged, non-rotating, spherically symmetric body of mass ''M''. ...
External links
* COSMOS - The SAO Encyclopedia of Astronomy
Black Hole
{{black holes
Black hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...