Today, observing the merger of a pair of supermassive black holes is no longer a sensation. However, the new discovery made by the Chandra X-ray space telescope is unique: three galaxies converge and prepare to merge at once a billion light-years from Earth.
Three supermassive black holes (one in each galaxy) are on the way to a meeting with each other. It was reported by a press release distributed by NASA on September 25, 2019.
A team of astronomers led by Ryan Pfeifle from George Mason University was looking for objects in which large galaxies and supermassive galaxies merge into millions and billions of solar masses – black holes located at their centers. This catastrophic process is accompanied by the mass death of stars, the absorption of huge flows of gas and dust, which, accelerating and burning, glow brightly at different wavelengths.
A large library of such objects, taken by the SDSS telescope located in New Mexico, the USA, is compiled in the Galaxy Zoo online archive, open to everyone. Professionals and astronomy enthusiasts install free software on their computers, participating in the search for new interesting images in this huge library. So, the SDSS J0849+1114 system was discovered by enthusiasts, to the study of which Ryan Pfeifl and his colleagues joined.
Astronomers conducted additional observations of SDSS J0849+1114 using space telescopes: infrared WISE, as well as X-ray Chandra and NuSTAR. To their surprise, three supermassive black holes were discovered in the system, separated by a distance of 10,000 to 30,000 light-years (less than 10 parsecs).
This discovery has been presented in an article presented in the arXiv.org preprint library and is being prepared for publication in The Astrophysical Journal.
The theory predicts that the presence of a third participant should accelerate the merger of the two nearest black holes. As a result, over time, they can form one huge black hole, or the third one can remain in close orbit around the new neighbor. Astronomers are sure to continue observing a rare triple system of supermassive black holes.