Astronomers have identified a pair of supermassive black holes that are nearly on a collision course. The finding was released by the press service of the Simons Foundation.
The two black holes sit just 750 light-years apart and are not expected to merge for several hundred million years. Yet this system is the closest approach to a merger ever observed by scientists. The tight separation allowed researchers to separate the two objects by combining data from seven different telescopes, including the Hubble Space Telescope. Supermassive black holes cannot be seen directly with optical instruments because they are cloaked by bright clusters of stars and by extremely hot gas that emits a lot of light and radiation as it is heated by gravity.
The detected objects weigh 200 million and 125 million solar masses, and their distance from Earth is about 480 million light-years. At the centers of most galaxies, these giants grow by pulling in surrounding gas, dust, stars, and even other black holes. Galaxies often interact when they pass by one another or merge, and in the coming millions of years the two black holes within this system will gradually spiral toward each other as surrounding material drains energy from their orbital motion. Over time, the pair is expected to produce strong gravitational waves and will eventually join to become a single, larger black hole.
Looking ahead, scientists hope to observe gravitational waves from similar binary systems at even later stages of their evolution, broadening our understanding of extreme gravity and galaxy growth.