An artist’s impression of two ancient galaxies, each hosting a supermassive black hole, in the process of merging. In a few tens of millions of years, the two quasars will marge, leaving a single, even more massive black hole in their wake. Image: NASA, ESA, and J. Olmsted (STScI)
Astronomers have spotted two close pairs of quasars in the process of merging as their host galaxies crash together in a slow-motion collision 10 billion years ago. The quasars in both pairs are separated by about 10,000 light years, closer than any two quasars yet found at such an early point in the evolution of the universe.
“We estimate that in the distant universe, for every one thousand quasars, there is one double quasar,” said Yue Shen, an astronomer at the University of Illinois and lead author of the paper in Nature Astronomy. “So finding these double quasars is like finding a needle in a haystack.”
Quasars are brilliant galaxies powered by supermassive black holes actively pulling in surrounding gas and dust, generating enormous energy as the in-falling material is heated to extreme temperatures. Quasars have dramatic effects on galaxy formation and evolution and dual quasars in merging galaxies offer insights ...