Scientists have discovered two black holes residing inside a 12 billion year old star cluster in the Milky Way.
The team, based at the International Centre for Radio Astronomy Research in Perth, Western Australia, announced Wednesday that each black hole was about 10 to 20 times the size of our Sun.
The cluster itself is called Messier 22 (M22) and is positioned approximately 10, 000 light years from Earth.
What makes this discovery all the more remarkable is that it challenges accepted theories that no more than one black hole can exist inside a globular star cluster.
These clusters are in fact fairly common in the Milky Way but — until now — there has been no recorded discovery of two black holes inside one.
The term black hole is used to describe a super dense region in spacetime that has a gravitational force so strong, even light cannot escape. Black holes are created when a very large star dies and then collapses in on itself.
James Miller-Jones, part of the team at the International Centre for Radio Astronomy Research, said:
“We were searching for one large black hole in the middle of the cluster, but instead found two smaller black holes a little way out from the centre.”
Miller went on to call the find “very surprising” adding that, “M22 may contain as many as 100 black holes but we can’t detect them unless they’re actively feeding on nearby stars.”
Current research into black holes using simulations has shown that many black holes are created early in a star cluster’s evolution. Specifically, scientists believed black holes are pulled in towards the middle of a cluster by gravitation. At this center these black holes would typically then be thrown out of the cluster, leaving only one behind.
However, this belief in will now have to revised in light of the M22 discovery.
Irrefutable data compiled from optical, infrared and X-ray evidence led the team to conclude that two black holes did indeed exist at the core of M22. Stefan Umbreit of the Northwestern University in Illinois’ Astrophysics Centre corroborated the team’s evaluation as “compelling.”
It is now believed that the two black holes found in M22 are the first pair to be found inside a globular cluster in our galaxy.