The first signs of dark matter interacting with a force other than gravity may have been found.
Until now it was thought that dark matter did not interact with anything other than gravity, earning it its ‘dark’ moniker and making its detection incredible difficult.
But the discovery of a ‘clump’ lagging behind a galaxy suggests that it may not be as oblivious to our universe as we thought.
Dark matter is confusing because it interacts with nothing - including itself.
This is despite seeming to account for 85 per cent of the universe’s mass and having an observable effect on galaxies; without dark matter, our galaxies would just ‘fall apart’ as they spin.
Aside from gravity, though, dark matter seemed to just pass through the universe without interacting with any other mass, such as humans, planets or stars.
Now an international team of researchers at Durham University have found a clump offset from a galaxy by 5,000 light-years.
The discovery was made around one of the galaxies in the Abell 3827 cluster, 1.4 billion light-years away.
The team used the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile, along with images from Hubble.
The offset is important because it is only possible if dark matter interacts with itself through forces other than gravity.
If the particles collide with each other, the friction from the collision would cause the dark matter to slow down, and fall behind the galaxy.
The nature of that interaction is unknown; it could be caused by well-known effects or some unknown force.
All that can be said at this point is that it is not gravity.
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