The pair of black holes is called PG 1302-102.
Earlier this year, ground-based telescopes spotted the two black holes 3.5 billion light-years away in the Virgo constellation. What makes the pair so special? They are separated by just a light-week. The next closest black hole pair is separated by 20 light-years.
Zoltan Haiman, a senior author of a study published today, explains the significance of this black hole pair. “This is the closest we’ve come to observing two black holes on their way to a massive collision,” said Haiman. “Watching this process reach its culmination can tell us whether black holes and galaxies grow at the same rate, and ultimately test a fundamental property of space-time: its ability to carry vibrations called gravitational waves, produced in the last, most violent, stage of the merger.”
Let’s take a step back for a second. Pg 1302-102 was discovered earlier this year by scientists at the California Institute of Technology. What caught their attention was a curious light signal coming from the center of a galaxy. Using ground-based telescopes, they were able to show the varying light signal is likely caused by two black holes orbiting each other every five years.