Hubble spots double quasars in merging galaxies

Peering back 10 billion years into the universe's past, Hubble astronomers found a pair of quasars that are so close to each other they look like a single object, because they reside in the cores of two merging galaxies. The gravitational between the two galaxies stretches them, forming long tidal tails and igniting a firestorm of starbirth. In a few tens of millions of years, the black holes and their galaxies will merge, and so will the quasar pair, forming massive black hole.