Rare intermediate-mass black hole has been discovered at the center of our galaxy

Just 0.1 light-years from the center of the Milky Way, there may be an intermediate-mass black hole—such objects' existence is yet to be proven, and the candidates can be counted on one hand. There is a gap between stellar-mass black holes and supermassive black holes, making the usual evolution of black holes inexplicable. Like other objects in the universe, black holes should feed and grow gradually, rather than jumping from one state to another.

About a quarter of a century ago, a compact star cluster named IRS 13 was discovered at the center of our galaxy. It has puzzled scientists from the beginning, and as observation instruments improved, it became even more mysterious. Initially, scientists thought it was a supermassive star. Then, IRS 13 was reclassified as a binary star system. Later, it was considered a Wolf–Rayet star. New research from astronomers at the University of Cologne showed that IRS 13 could be a small star cluster with a compact mass source inside.

But there's a catch. The IRS 13 cluster is located near the black hole Sagittarius A* (Sgr A*) with a mass of 4.3 million solar masses, situated at the center of the Milky Way. The black hole Sagittarius A* should have influenced the trajectory of stars in the IRS 13 cluster and torn it apart. However, this has not happened, leading scientists to suspect the existence of some "cementing" center within the cluster.

Analysis of the movement of stars in IRS 13 and modeling showed that a compact, invisible object with a mass of 30,000 solar masses could be in the middle of the cluster. Since there are no sufficiently confirmed black holes in the mass range between 100 and 100,000 solar masses, the confident discovery of an object with a mass of 30,000 solar masses promises to be a significant event in astronomy. This could be the first confirmed intermediate-mass black hole, which could not have appeared after a supernova explosion or from the merger of two star cores. It must have fed and evolved in the usual way to grow to a measurable mass.

Scientists tried to learn more about the mysterious object in the center of IRS 13 and discovered X-ray radiation and a cloud of ionized gas rotating at a speed of 130 km/s at the supposed location of the black hole, providing further evidence of the discovery of a black hole. Since one study cannot serve as reliable proof of an extraordinary discovery, observations of the IRS 13 object will continue. If a black hole is indeed found there, it will also be considered a candidate for absorption by the black hole Sagittarius A*, taking another step towards the usual evolution of black holes: they do indeed feed and grow.