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(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 ...
In physics, black hole thermodynamics [1] is the area of study that seeks to reconcile the laws of thermodynamics with the existence of black hole event horizons.As the study of the statistical mechanics of black-body radiation led to the development of the theory of quantum mechanics, the effort to understand the statistical mechanics of black holes has had a deep impact upon the ...
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.
The Schwarzschild solution, taken to be valid for all r > 0, is called a Schwarzschild black hole. It is a perfectly valid solution of the Einstein field equations, although (like other black holes) it has rather bizarre properties. For r < r s the Schwarzschild radial coordinate r becomes timelike and the time coordinate t becomes spacelike. [22]
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 formula for the Bekenstein–Hawking entropy (S) of a black hole, which depends on the area of the black hole (A). The constants are the speed of light ( c ), the Boltzmann constant ( k ), Newton's constant ( G ), and the reduced Planck constant ( ħ ).
A black hole of one solar mass (M ☉ = 2.0 × 10 30 kg) takes more than 10 67 years to evaporate—much longer than the current age of the universe at 1.4 × 10 10 years. [24] But for a black hole of 10 11 kg, the evaporation time is 2.6 × 10 9 years. This is why some astronomers are searching for signs of exploding primordial black holes.
The Carter constant is a conserved quantity for motion around black holes in the general relativistic formulation of gravity. Its SI base units are kg 2 ⋅m 4 ⋅s −2.Carter's constant was derived for a spinning, charged black hole by Australian theoretical physicist Brandon Carter in 1968.