A study team led by Karina Voggel, an astronomer at the Strasbourg Observatory, has discovered the nearest pair of supermassive black holes yet spotted using the Very Large Telescope (VLT) at the European Southern Observatory (ESO).
These black holes are significantly closer to the earth than all black holes previously detected besides the one at the center of our galaxy the Milky Way. They are also much closer to each other than all the other pairs of supermassive black holes spotted to date, and they will ultimately merge into a single gigantic black hole, according to current estimates.
The two black holes are about 89 million light-years away from the Earth and are located in the galaxy NGC 7727. Although it seems to be a long-distance away, it is far closer than the previous record holders, who are 470 million light-years distant.
The bigger of these two ogres is positioned in the center of the galaxy, while the smaller one is placed on the periphery. When compared to the Sun, the big one is roughly 154 million times more massive, while the latter is around 6.3 million times more massive than our star. However, they are getting closer to one another. According to the study’s co-author Holger Baumgardt, the two objects will merge into a single black hole, most likely within the next 250 million years.
The presence of these two objects in the galaxy had long been suspected, but never confirmed. For this study, the researchers set out to measure their mass using the Multi-Unit Spectroscopic Explorer (MUSE), an instrument of the Very Large Telescope (VLT) in Chile. The latter allowed them to analyze the gravitational influence exerted by these two objects on the stars which surround them.
NGC 7727 is a very irregular galaxy with amorphous spiral arms, which suggests that it could be the result of a past galaxy merger. The presence of these two black holes approaching each other confirms this idea.
For the authors, who publish their work in the journal Astronomy & Astrophysics, this new discovery suggests that there may be many more of these relics in the universe. Each of them could also contain many hidden massive black holes. To find them, researchers will soon be able to count on ESO’s European Giant Telescope (ELT), which is expected to come into operation during the decade in the Atacama Desert, Chile.