Behind these two bright points of light are two supermassive black holes that are very close to each other in the heart of a distant galaxy. It is the closest and closest pair of such black holes to date.
Researchers led by the astronomer Karina Voggel from the Astronomical Observatory in Strasbourg have discovered the closest known pair of supermassive black holes with the help of the Very Large Telescope of the European Southern Observatory in Chile. It is located in the galaxy NGC 7727 in the constellation Aquarius and is also the pair of supermassive black holes closest to Earth that has been observed so far.
The pair is only about 1,600 light years apart. “It is the first time that we have found two supermassive black holes that are so close to each other, less than half the distance of the previous record holder,” explains Voggel. The data suggest that the two black holes will merge into one gigantic black hole within the next 250 million years. Events like this could explain how the most massive black holes in the universe are formed.
The short distance of only around 89 million light years from Earth made a new method of determining mass possible: The movements of nearby stars show the influence of the enormous gravitational effect of the black holes, so that conclusions can be drawn about their mass. The scientists confirmed that the 154 million and 6.3 million solar masses heavy black holes are supermassive.
Supermassive black holes are located in the center of massive galaxies. When galaxies merge, their central black holes often converge and, after a period of spiraling orbiting, also merge. “Our discovery suggests that there may be many more of these galaxy merger relics and that they contain many hidden massive black holes that are still waiting to be found, ”says Voggel. “That could increase the total number of known supermassive black holes in the local universe by 30 percent.”