A blazar is a supermassive black hole. Occasionally, one fires an intense beam of radiation in the direction of Earth. Ejected matter travels several light years before being accelerated to nearly the speed of light. This is the conclusion of an international team of astronomers who used the Fermi Gamma-ray Space Telescope to study radiation such a beam. The result conflicts with some theories that suggest the acceleration occurs much nearer to the black hole.
Maybe a billion times heavier than the Sun, blazars dominate the centre of most large galaxies, and are often encircled by a thin "accretion disc" of matter that swirls into the black hole like water going down a drain. Near the centre, the matter is so hot that a rotating plasma that generates huge magnetic fields. is created.
In some supermassive black holes the magnetic field lines pop out of either side of the disk like uncoiling springs, taking jets of matter with them. Occasionally, one of thes jets happens to point towards Earth and astronomers see a "blazar" – literally, a blaze of radiation at energies all the way up to the highest detectable gamma rays. The radiation is focused into a tight beam by a process called relativistic beaming, which means that it is created in a region of the jet that has been accelerated to about 95% of the speed of light
Read the whole story at http://physicsworld.com/cws/article/news/41749
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