Black Holes Probably Smaller than Expected

(Pug) black holes are perhaps ten times smaller than previously thought. To this end the University of Gottingen astrophysicists come in a study on Thursday 17 February 2011, in the prestigious journal Nature published. Supermassive black holes are the cores of galaxies and have a mass of up to one billion solar masses. They are surrounded by a so-called accretion disk, in which central matter of the galaxy accumulates. Matter at the inner edge of the disk crashes due to the high attraction of the black hole at very high speed into this. The researchers analyzed

Sketch of a flat accretion disk that spins around a black hole. Source: NASA / Dana Berry, Skyworks Digital

the light emission of 37 galaxies and found it the first time clearly rotational speed of the disk matter measure. By the third Kepler's law can be based on the velocity and the distance from each other, the body mass of the black hole calculate. The resulting calculated masses are far lower than previously thought, and the mass of black holes because their size is proportional to, so they are also smaller than expected.

The scientists registered rotational speeds between several hundred and several thousand kilometers per second. Inwards, ie towards the black hole, the speed to - analog to move into our solar system the inner planets faster than the outer. Furthermore, the Gottingen astrophysicists were first statements about the geometry of the clouds of matter in the environs of a black hole: At high rotational speeds, the surrounding matter in the form of a flat disk is arranged in slowly rotating black holes in the form of a thick disk.

Publication: Wolfram Kollatschny, Matthias Zetzl. Broad-line active galactic nuclei rotate faster than narrow-line ones. Nature. DOI: 10.1038/nature09761.

Source: University of Gottingen