Scientists have recently discovered 19 more dwarf galaxies that seem to be missing dark matter. Physicists are not sure why.
Studying dark matter is indeed a tricky bussiness.
Dark matter is like an invisible force that pulls together atoms of gas to form galaxies. So, dark matter has to be present in order for galaxies to exist.
We know there’s dark matter in a galaxy because it makes the matter in that galaxy swirl faster than it would if the observable matter was the only matter in it.
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But recently, scientists have observed 19 dwarf galaxies that seem to be missing a whole lot of dark matter. And no one knows why.
Researchers have found that they behave as if they’re dominated by baryons — the particles that make up ordinary matter. The light-bending halos that help us observe dark matter are missing from these galaxies.
“This new class of galaxy is straining our ability to explain all galaxies in one cohesive framework,” says Kyle Oman, an astrophysicist at Durham University in England who was not involved in this research.
One possible answer is that the researchers have simply made a mistake. Perhaps there was an error while calculating the angle of the galaxy from Earth.
If the angle of the host galaxy relative to Earth is incorrectly measured, that can screw up the calculations, Oman said.
And other events, like a supernova, can also have an effect on the rotation of a galaxy. A supernova can speed up the gas in a normal galaxy. Therefore, creating rotation curves that look from Earth like the new-found dwarf galaxies.
However, if scientists do discover that dark matter is missing from these galaxies, then they will need to re-think their ideas about current theories of how the universe formed.
Physicists said the only way to figure out what’s going on is to study these galaxies in much more detail using different tools and confirm that what seems to be happening there is really happening.
The researchers reported their study Nov. 25 in the journal Nature Astronomy.