Until now, the main suspects for what made these supermassive black holes into active galactic nuclei were galactic mergers. The crashes were thought to be what drove matter into the black holes, ramping up their activity. [Gallery: Black Holes of the Universe]
But after looking at telltale signs of galactic mergers among 140 active galaxies, as well as more than 1,200 comparable inactive galaxies, over the last 8 billion years, a team of astronomers found no significant link between the galaxy crashes and black hole outbursts.
“The implication is that the universe is not evolving in such a violent way as previously thought, at least for the last 8 billion years,” research team leader Mauricio Cisternas, an astronomer at the Max Planck Institute for Astronomy in Heidelberg, Germany, told SPACE.com. The universe is thought to be about 13.7 billion years old.