How did they catch them? Thanks to an astronomical detector buried in the Antarctic ice. It is a vision of our galaxy never before captured. In it, we can see for the first time the ghost particles of the Milky Way: the neutrinos.
Scientists turned a large block of Antarctic ice into a detector. “This is the first time we see our galaxy using particles instead of photons (of light).” Professor Subir Sarkar of Oxford University announced. “It provides insight into the high-energy processes that drive our galaxy.”
Neutrinos can be thought of as astronomical messengers pointing to these fundamental processes. They are created when particles called cosmic rays collide with other matter. It happens almost at the speed of light. Detecting these collisions means capturing neutrinos. And that’s not easy.
“The neutrino is a ghost particle. Basically, it has almost no mass,” Professor Sarkar explained. “They can pass through the galaxy without interacting with anything. To see them you need a huge detector,” he added. The detector the scientists and engineers designed is called IceCube. It has thousands of sensors located on long cables placed in a perforated ice cube 1 km on a side. The entire structure is buried near the South Pole. Every time a neutrino interacts with one of the billions of ice molecules, that interaction is captured.
“By knowing which sensor is triggered at what time, we can reconstruct the direction of the neutrino.” The discovery was published in the journal Science. A century has passed since astronomer Edwin Hubble discovered that the Milky Way was only one of millions of galaxies. Humans have been trying to understand it for millennia.
“We have seen it in many wavelengths of light, such as radio waves and gamma rays. But it has always been captured in electromagnetic radiation at all wavelengths of light or photons. It is the first ‘map’ of our galaxy in high-energy neutrinos.” Now we can begin to better understand the Milky Way’s ghost particles.
Researchers will spend the next 5 to 10 years trying to answer questions that “we can finally ask. We’ll see where the answers take us.