Ghostly Milky Way Neutrinos Reveal Secrets of Our Galaxy's Stellar Core

Earth is constantly bombarded by neutrinos from the Milky Way, with billions of these ghostly particles passing through us every second. Scientists are now detecting them in greater detail than ever before. Two key detectors—IceCube in Antarctica and XENONnT in Italy—have recently made breakthroughs in measuring these elusive cosmic messengers.

The influx of stellar neutrinos is currently at its highest due to ongoing star formation in the galaxy's thin disk. Most of these particles carry energies around 0.5 MeV and come from massive stars. A staggering 100 billion neutrinos near 0.1 MeV strike each square centimetre of Earth every second, while at lower energies (0.01 MeV), the number rises to about 1 billion per second.

The majority of detected neutrinos originate from regions 16,000 to 32,000 light-years away, with the galactic centre acting as a major source. Even high-energy neutrinos, exceeding 1 MeV, still arrive in quantities ranging from 100,000 to 1 million per square centimetre.

Recent detections have come from IceCube, which identified Milky Way neutrinos at higher energies, and XENONnT, which in July 2024 announced the first observation of solar neutrinos via boron-8 nuclear recoils. Meanwhile, Germany's KATRIN experiment, set to begin operations in 2026, will search for sterile neutrinos in the keV range.

Because neutrinos escape directly from stellar cores, they offer rare insights into the life cycles of stars and the galaxy's structure. Precise measurements could also help answer long-standing questions in physics and cosmology.

With detectors like IceCube and XENONnT already providing new data, the study of Milky Way neutrinos is advancing rapidly. Future experiments, including KATRIN, will expand our understanding of these particles and their role in the universe. The findings could reshape our knowledge of stars, galaxies, and fundamental physics.