Usually, a galaxy contains only one supermassive black hole. Only rarely is a pair of such objects found there. But recently, three were discovered at once in a system very far from us.
Three Supermassive Black Holes in One Galaxy
Recently, an international team of astronomers led by scientists from the Max Planck Institute for Extraterrestrial Physics reported the discovery of the galaxy J0148-4214. In it, they found signs of the presence of as many as three supermassive black holes. This was reported by Phys.org.
Supermassive black holes are the heaviest individual objects in the Universe. They are usually located at the centers of galaxies and slowly grow together with them. From time to time, however, they are found in pairs, which indicates mergers that are currently considered the main mechanism through which they gain mass.
However, the presence of three supermassive black holes at once in J0148-4214 is a truly important event. The fact that the galaxy itself is located 12.5 billion light-years away makes it even more interesting. This means that we see it as it was about 1.2 billion years after the beginning of the Universe.
Why Three Black Holes Are So Important
To determine that the galaxy J0148-4214 contains as many as three supermassive black holes, scientists had to use spectroscopy. It revealed three regions in which hydrogen atoms are moving at velocities close to the speed of light. Two of them were located in the center. The third was near the edge of the galaxy’s disk.
To distinguish the two central objects, scientists had to measure the relativistic shift of the lines in their spectra with particular precision. It turned out that the pair in the center consists of a large black hole with a mass of 80 million solar masses and a much smaller one with a mass of 0.6 million solar masses, separated from it by a distance of 620 light-years.
The third black hole has a mass of about 2 million solar masses. It is believed to be the remnant of a relatively recent merger and is expected to remain a separate object for quite a long time. The first two, however, are expected to merge within the next several hundred million years.
But the most important aspect of this story is the presence of as many as three supermassive black holes in a very early galaxy. This indicates that mergers occurred much more frequently at that time than they do today. And this could provide a good explanation for the excessively large masses of these objects in the modern Universe.
