Hundreds of rogue black holes may be swarming around the Milky Way, gobbling up anything that gets in their paths. Research by US scientists suggests that the cosmic cannibals, left over from the early days of the universe, are drifting through the outskirts of our home galaxy.
Fortunately the closest lie thousands of light-years away from the Earth and so are no threat to our planet.
The existence of the massive black holes, left over from when the galaxies were being formed, is proposed by astronomers Ryan O’Leary and Avi Loeb of Harvard-Smithsonian Center for Astrophysics in Massachusetts.
They believe the black holes were created and then ejected when lightweight dwarf galaxies collided to build bigger galaxies as the universe was forming. However, they were not flying fast enough to escape the Milky Way’s neighbourhood entirely and they now travel in a halo around it.
Although they cannot be directly seen, each black hole is estimated to contain the mass of between 1,000 and 100,000 suns. Despite being invisible they reveal their existence through clusters of stars that they pulled out of the dwarf galaxies with them.
It has long been known that a monster black hole lurks at the centre of the Milky Way, as one does at the heart of many galaxies. But the celestial wanderers are a new idea.
Dr Loeb said: “These black holes are relics of the Milky Way’s past. We are archaeologists studying those relics to learn about our galaxy’s history and the formation history of black holes in the early universe.”
Loeb and O’Leary’s research will be published in the UK science journal Monthly Notices of the Royal Astronomical Society.
Picture: An artist’s impression of a drifting black hole. Credit:David A. Aguilar (CfA)