A team led by Karina Voggel, astronomist at the Strasbourg observatory in France, has discovered two super -massive black holes that are caught in an ever increasing dance. Just 1600 light years separate them from each other, which means that they will probably be fused into a single black hole in a huge outbreak of energy in 250 million years.
And the discovery in the galaxy NGC 7727 has another special feature: The two black holes are only 89 million light-years away from Earth, closer than any other pair – and much closer than the previous record holder, which is located 470 million light-years away.
In the journal "Astronomy & Astrophysics", the research group provides further key data of the system. Accordingly, the larger of the two holes comprises a mass that corresponds to 154 million times the mass of the Sun. It is located in the center of NGC 7727. The smaller one contains the mass of 6.3 million suns. It probably once formed in a smaller galaxy that merged with that of the larger one.
Astronomers had already suspected that two such mass giants are located in the center of NGC 7727. However, their existence has not yet been demonstrated, since they do not emit a high -energy radiation. Such "silent" black holes do not get any matter that would make the surroundings illuminate when they fall into the black hole.
Instead, Voggel and colleagues used the possibilities of the Multi-Unit Spectroscopic Explorer (MUSE) instrument on the Very Large Telescope (VLT) of the European Southern Observatory (ESO) at Paranal in Chile. With it, they were able to indirectly prove the existence of black holes. Using high-resolution spectroscopy, they observed that stars move on tight orbits around the assumed positions of the two black holes. The stars can only do this if they are bound by the gravitational force of a central object containing millions of solar masses – and this can only be a black hole. How fast the stars move provides information about the mass in their common center.
"Our discovery indicates that there could be many more of these relics of galaxy melting out there and that they could contain many hidden mass-rich black holes that are still waiting to be discovered," says Voggel in an ESO press release. "This could increase the total number of well -known supermassed black holes in the local universe by 30 percent."
