Astronomers have identified the nearest pair of supermassive black holes to Earth ever confirmed, located just 89 million light-years away and separated by only 1,600 light-years—primed for a future merger.
Sagittarius A*, the supermassive black hole at the Milky Way's core, lies just 26,000 light-years from Earth. But these cosmic giants can also form pairs. Previously, the closest known duo was over 470 million light-years distant. Now, experts have pinpointed a pair in NGC 7727 at 89 million light-years away.
Remarkably, they are only 1,600 light-years apart—less than half the separation of the prior record holders. The larger black hole anchors the galaxy's center, boasting a mass 154 million times that of the Sun, while its companion is 6.3 million solar masses. "Our analyses indicate they will merge into one within about 250 million years," notes study co-author Holger Baumgardt.
Long suspected in NGC 7727, these black holes were confirmed using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) in Chile. This instrument revealed their gravitational effects on surrounding stars.
NGC 7727's irregular, amorphous spiral arms point to a past galaxy merger, now affirmed by this approaching black hole pair.
Publishing in Astronomy & Astrophysics, the team suggests many galaxies harbor such hidden pairs—relics of mergers awaiting discovery. The upcoming Extremely Large Telescope (ELT) in Chile's Atacama Desert will soon aid the hunt.
