A team of Penn State University and international scientists revealed that NASA used the Anktika Impact Transient Antenna (ANITA) experiment on a high-altitude balloon in Antarctica to detect mysterious radio signals from beneath the Antarctic ice. This discovery has not yet been clearly explained.
Between 2016 and 2018, scientists using ANITA detected multiple unusual radio pulses while collecting data above the Antarctic ice. The mission was originally designed to study distant cosmic phenomena by detecting radio waves produced by cosmic rays hitting the atmosphere. But the source of some of the signals seemed to come from beneath the ice, which was completely inconsistent with existing particle physics models, leading researchers to suspect that unknown particles or interactions might have been discovered.
To investigate further, the team analyzed fifteen years of cosmic ray data from the Pierre Auger Observatory in Argentina, and recently published relevant results in Physical Review Letters. The study pointed out that the signal detected by ANITA needs to pass through thousands of kilometers of rock, but according to conventional theory, this propagation path will completely absorb radio waves, and the signal should not be detected. The results also show that the Pierre Auger Observatory has not detected similar events, so it cannot currently prove the existence of new physical laws, but it adds new information to the mystery.
Stephanie Wissel, an associate professor at Penn State University, pointed out that these steep-angle radio events have not been captured by conventional large-scale observation experiments, which further proves that these abnormal signals are not neutrinos. Neutrinos are particles that barely interact with matter. They are abundant in the universe but are extremely difficult to detect. Scientists are working to build more sensitive large neutrino radio telescopes to catch similar signals.
The current analysis has excluded common particles and background noise, and has also been cross-validated with data from the IceCube experiment and the Pierre Auger Observatory. Other detectors did not detect events that could explain ANITA's unusual signal, further narrowing the scope of explanations.
The Wissel team is designing the next-generation detector PUEO, which is expected to improve detection sensitivity and hopes to reveal the truth about these mysterious signals in the future. She said that there is still no conclusion on the anomaly at this stage, and it is expected that the new equipment will help better identify these abnormal events and the source of the neutrino signal.
The research was funded by the U.S. Department of Energy and the National Science Foundation.
Compiled from /ScitechDaily