Wednesday, June 2, 2010

Retrograde Black Holes

A new study finds that black holes that spin in the opposite direction of the spin of the accretion disks that surround them-- retrograde black holes-- eject more powerful jets of energy and matter than do prograde black holes, which spin in the same direction as their accretion disks.

The reason seems to be that retrograde black holes have more room between them and the inner edge of their accretion disks, which gives the black holes' magnetic fields more room to develop and strengthen. It is the magnetic field of a black hole that sustains and directs the jets.

This finding is important in understanding star formations in galaxies, and, therefore, the development of galaxies. A monster black hole sitting at the center of a galaxy affects the development of that galaxy in various ways. One way is the jet sweeping through matter, clearing some areas and concentrating matter in others. Stars eventually form in knots of matter where the density becomes high enough to ignite the nuclear cycle.

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