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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 ...
As the rotation rate of the black hole increases to the maximum of , the prograde ISCO, marginally bound radius and photon sphere radius decrease down to the event horizon radius at the so-called gravitational radius, still logically and locally distinguishable though. [5]
In the mathematical description of general relativity, the Boyer–Lindquist coordinates [1] are a generalization of the coordinates used for the metric of a Schwarzschild black hole that can be used to express the metric of a Kerr black hole. The Hamiltonian for particle motion in Kerr spacetime is separable in Boyer–Lindquist coordinates.
The equatorial (maximal) radius of an ergosphere is the Schwarzschild radius, the radius of a non-rotating black hole. The polar (minimal) radius is also the polar (minimal) radius of the event horizon which can be as little as half the Schwarzschild radius for a maximally rotating black hole. [2]
A black hole with the mass of a car would have a diameter of about 10 −24 m and take a nanosecond to evaporate, during which time it would briefly have a luminosity of more than 200 times that of the Sun. Lower-mass black holes are expected to evaporate even faster; for example, a black hole of mass 1 TeV/c 2 would take less than 10 −88 ...
The radius of the sphere of influence is called the "(gravitational) influence radius". There are two definitions in common use for the radius of the sphere of influence. The first [ 1 ] is given by r h = G M BH σ 2 {\displaystyle r_{h}={\frac {GM_{\text{BH}}}{\sigma ^{2}}}} where M BH is the mass of the black hole, σ is the stellar velocity ...
to the RMS velocity ΔV of gas moving near the black hole in the broad emission-line region, measured from the Doppler broadening of the gaseous emission lines. In this formula, R BLR is the radius of the broad-line region; G is the constant of gravitation; and f is a poorly known "form factor" that depends on the shape of the BLR.
An animation of how light rays can be gravitationally bent to form a photon sphere. ACoolphoton sphere [1] or photon circle [2] arises in a neighbourhood of the event horizon of a black hole where gravity is so strong that emitted photons will not just bend around the black hole but also return to the point where they were emitted from and consequently display boomerang-like properties. [2]