Evrim Yazgin
Cosmos science journalist
Unexplained chemical reactions observed at the centre of the Milky Way galaxy could be caused by the existence of a type of dark matter not accounted for in current physics.
“At the centre of our galaxy sit huge clouds of positively charged hydrogen, a mystery to scientists for decades because normally the gas is neutral,” says Shyam Balaji from King’s College London and one of the lead authors of a new paper published in the Physical Review Letters.
“So, what is supplying enough energy to knock the negatively charged electrons out of them?”
Astronomers have called this area of ionised hydrogen gas clouds the Central Molecular Zone (CMZ).
“The energy signatures radiating from this part of our galaxy suggest that there is a constant, roiling source of energy doing just that, and our data says it might come from a much lighter form of dark matter than current models consider,” Balaji says.
Previous attempts to explain the ionisation relied on cosmic rays – ultrafast and energetic particles. But the energy signatures observed in the CMZ don’t aren’t large enough to be attributed to cosmic rays.
The culprit could be a new candidate for dark matter.
Dark matter is the elusive substance which, according to gravitational observations, makes up about 85% of all the matter in the universe.
Dark matter has never been directly detected because it barely interacts with “normal” visible matter. The best theory for what dark matter is suggests that the substance is made of a group of particles called “Weakly Interacting Massive Particles” (WIMPs).
Even so Balaji’s team suggests that dark matter particles may actually be a lot lighter than previously thought. And this new theory about the strange processes in the heart of the Milky Way could help explain the nature of dark matter.
“The search for dark matter is one of fundamental science’s most important objectives, but a lot of experiments are based on Earth, waiting with hands outstretched for the dark matter to come to them,” Balaji says. “By peering into the centre of our Milky Way, the Hydrogen gas in the CMZ is suggesting that we may be closer to identifying evidence on the possible nature of dark matter.”
