The heaviest pair of Supermassive Black Holes ever observed: Almost 28 billion solar masses
A group of researchers has carefully analyzed a very particular pair of supermassive black holes: not only are they incredibly close to each other but they are also the heaviest ever observed so far.
The two record-breaking supermassive black holes are located about 750 million light years away from us, in galaxy B2 0402+379, also called 4C +37.11.This is an elliptical-shaped radiogalaxy, that is, a galaxy characterised by an emission of very intense radio waves, even hundreds of times higher than those of normal visible galaxies.
The peculiarity of this binary system of black holes is that they are not only the heaviest ever observed, with a total mass of about 28 billion solar masses, but they are also the ones with the smallest separation ever observed directly. The two celestial objects are just 24 light-years or 7.3 parsecs apart and have an orbital period of 30,000 years.
A record binary system
The study of these binary systems is very important to understand the mechanisms that regulate the universe but also because the possible collision and fusion of this pair would cause very strong gravitational waves.
That is why a group of astronomers dedicated themselves to the study of this pair using the data collected by the Gemini North telescope, one of the two telescopes that make up the Gemini Observatory, two twin optical telescopes of about 8 meters located one in the northern hemisphere and the other in the southern hemisphere so as to have a complete coverage of both celestial hemispheres.
Obviously Gemini North is located in the northern hemisphere, on the dormant volcanoMauna Kea, at over 4,200 meters above sea level, in Hawaii, and is a relatively recent telescope. In fact, it saw its first light in 1999 (the term first light is the first observation made by a telescope after its construction), while it began its true observation activity in 2000.
This telescope is not only among the most advanced for observation in the optical and infrared band but thanks to the excellent weather conditions and the high altitude it can enjoy optimal visual conditions to be able to make astronomical observations of the highest level.
It is precisely thanks to this incredible resolution that we were able to observe and distinguish, and therefore see separately, the two supermassive black holes that are the subject of this study, which is absolutely not a small thing since they are only 24 light years apart.
They get closer and closer, will they end up colliding?
Their distance over the years has progressively diminished and it is therefore normal to ask whether a merger of these two supermassive objects is expected in the future or not.
In general, thanks to gravitational wave interferometers, fusions of binary systems of black holes have been observed but they have always been black holes of stellar mass, similar observations have never been made for supermassive ones.
At the moment the two bodies are in a phase of stagnation and we are still unable to say if and for how long they will still remain in this limbo, as can be read from this recent article published in The Astrophysical Journal. However, to have an eventual fusion it will take time of the order of millions of years and the gravitational waves that would be created would be a hundred million times more powerful than those observed due to the fusion of stellar black holes.