Researchers estimate that only 0.3% of all known quasars have two supermassive black holes on a collision course with each other.
In the Universe, sometimes a supermassive black hole encounters a large amount of matter and, thanks to its gigantic gravitational force, it “devours” it, producing an intense glow and forming a quasar.
If this type of object is rare, finding two of them orbiting each other is even more difficult – a mission for some of the best astronomers in the world, for sure.
In an article recently published in The Astrophysical Journal, researchers at the University of Tokyo, Japan, report that they found three pairs of quasars.
As if that were not enough, they also discovered the pairs of supermassive black holes inside them are on a “collision course”, meaning they will merge very soon.
According to the scientists, it is estimated that only 0.3% of all known quasars have two supermassive black holes on a collision course with each other.
“In spite of their rarity, they represent an important stage in the evolution of galaxies, where the central giant is awakened, gaining mass, and potentially impacting the growth of its host galaxy,” said Shenli Tang, co-author of the study and a graduate student at the University of Tokyo.
As the astronomers explain, what makes it particularly difficult to detect a pair of quasars is the intensity of the light emitted: it is so much light that it is complicated to know whether it comes from one or two supermassive black holes. In addition, it is necessary to observe a wide area of the sky.
According to the researchers, the initial objective of the study was not to detect pairs of quasars, but the research ended up going in that direction.
The team evaluated the 34,476 quasars known thanks to the Sloan Digital Sky Survey and detected 421 potential pairs.
“Honestly, we didn’t start out looking for dual quasars,” said John Silverman, study leader and researcher at the Kavli Institute for the Physics and Mathematics of the Universe. “We were examining images of these luminous quasars to determine which type of galaxies they preferred to reside in when we started to see cases with two optical sources in their centers where we only expected one.”