Astronomers Spot Two Supermassive Black Holes on a Collision Course - Gizmodo

Supermassive black holes lurk at the center of galaxies—our own galaxy hosts Sagittarius A*, a roughly 4 million solar mass black hole 26,000 light-years from Earth.

“This is in theory observable, but this stage in black hole evolution lasts only a short time over a cosmic timescale, and so far we have not observed it.” Voggel, an astronomer at the University of Strasbourg in France, said that unknown galaxy merger relics like it could increase the total number of supermassive black holes by up to 30%.

“Currently, LIGO can detect gravitational wave events from black holes that merge that have a couple times the mass of our Sun,” Voggel added.

“The small separation and velocity of the two black holes indicate that they will merge into one monster black hole,” said study author Holger Baumgardt, an astrophysicist at the University of Queensland, Australia, in an ESO release.

“This detection of a supermassive black hole pair is just the beginning,” said co-author Steffen Mieske, an astronomer at ESO in Chile, in the same release.