With the help of a giant ice cube at the South Pole, researchers have detected neutrinos from the Milky Way for the first time. It is very difficult to track down “ghost particles”.
Antarctica – In Antarctica, near the Amundsen-Scott South Pole Station, there is an unusual scientific instrument in the eternal ice: the Ice Cube Neutrino Observatory. The detector system is just what its name says: an ice cube. Its edge is 1 kilometer long, so it contains 1 cubic kilometer of ice. In it, science is looking at something very special: neutrinos.
These electrically neutral elementary particles are extremely volatile – they hardly interact with ordinary matter. They race through unnoticed, which is why they’re called “ghost particles.” To be able to detect volatile particles, you need as much matter of matter that is pure as possible and can interact with neutrinos. One such material is water – of which Antarctica has ample supplies in frozen form.
“Ghost particles” from the Milky Way race across the ice and emit light
When a neutrino interacts with a water molecule, electrically charged particles are created that race across the ice at nearly the speed of light and emit light in the process — Cherenkov radiation. This radiation is captured at the giant IceCube detector in Antarctica using 5160 photointensifiers. And that’s not all: the researchers can also determine which direction the light is coming from—an indication of which direction the neutrinos came from.
So far, IceCube has only been able to detect high-energy neutrinos from distant galaxies, but it was expected that high-energy neutrinos and gamma rays are also produced in our Milky Way by the interaction of cosmic rays with gas and dust. The latter has already been proven, but the search for Milky Way neutrinos has so far been unsuccessful.
However, my research team has now succeeded in detecting high-energy neutrinos from the Milky Way for the first time. Until now, astronomers have searched in vain, since neutrinos are also produced in the Earth’s atmosphere – this noise is superimposed on a signal from the Milky Way, which researchers have been looking for for a long time.
Researchers discover neutrinos from the Milky Way – a new research method
The detection is made possible by a machine learning-based method primarily developed at TU Dortmund. “These improved methods mean that we have been able to use about ten times more neutrinos than before, and with better directional accuracy,” Mirko Honnefeld of TU Dortmund explains to the news agency. dpa. “Overall, our analysis was three times more sensitive than previous research methods.” In addition to the new method, the researchers filtered the data that came from the direction of the Milky Way’s center. The results of the study were in the journal Sciences published.
The new IceCube data provides the first image of the Milky Way as it would appear if neutrinos could be seen. “This image confirms our previous knowledge about the Milky Way and cosmic rays,” IceCube researcher Steve Sclafani confirms to dpa. In the future, more data will be collected and methods will be improved. “This gives us an image with better resolution than ever before,” says Denise Caldwell. Next, the researchers want to know exactly where neutrinos originate. “Of course, we also hope to discover previously unknown and never-before-seen structures in our Milky Way,” Caldwell continues. (tab/dpa)