Every galaxy has black holes at their center.
While the black hole is active, traps and swallows all matter around it, like a
whirlpool. When he is not able to swallow again, the matter continues to
revolve around him, but not within. The galaxies whose black hole is still
active called active galaxies.
Active galaxies are famous
by their shape and the large whole of radiation they emanate. The black hole
core is surrounded by a bright disc of matter, dust and hot gas. It is called
the accretion disk, and spirals while emitting high energy radiation. Since the
poles, the black hole space launches huge jets of particles, which can measure
thousands of light years in length. The Milky Way galaxy was also active in the
past.
