Astronomers detect black holes 10 times the size of our Sun near Earth

Both black holes are located within the Milky Way galaxy and are roughly 10 times more massive than our Sun.

Though it's surprising that such massive objects could exist so close to Earth without being detected for so long, black holes are notoriously difficult to detect.

Unlike most black holes that have been detected to date, no remnants of other stars or gas clouds are floating near Gaia BH1 and Gaia BH2 – scientists have traditionally detected the cosmic giants by finding these remnants left over after the black hole ingests a neighboring space object.

Scientists refer to black holes that aren't snacking on stars or other objects as "dormant" or inactive black holes. As Gaia BH1 and Gaia BH2 are dormant, the scientists had to use a different method to detect the black holes. They detailed their method in a new paper in the Monthly Notices of the Royal Astronomical Society.

New method allows scientists to detect dormant black holes

The researchers detected the two black holes by carefully observing and tracking the movement of two sun-like stars orbiting the space giants.

These stars displayed a very faint wobble, allowing the scientists to determine they were orbiting an invisible object with massive gravity – a black hole.

The team first discovered the black holes last year, but follow-up observations have shed new light on Gaia BH1 and Gaia BH2. Their latest findings show that the black holes behave differently from any observed before, meaning they may be part of a new category of cosmic giants.

"What sets this new group of black holes apart from the ones we already knew about is their wide separation from their companion stars," Kareem El-Badry, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and the discoverer of the new black holes, explained a press statement. El-Badry also added that these inactive black holes "likely have a completely different formation history than x-ray binaries [stars orbiting black holes that emit x-ray and radio wave radiation]."

Follow-up observations from ESA's Gaia mission may be able to unearth more of these hidden black holes that may be lurking much nearer than once thought.