A team of researchers trying to locate neutrinos in the Antarctic stumbled upon unusual radio signals coming from below the Earth’s surface rather than space. The Antarctic Impulsive Transient Antenna (ANITA), a range of equipment flown up on a balloon to capture waves from cosmic rays before they strike the Earth’s surface, picked up the signals. This occurrence is contrary to the current commonly accepted norms of particle physics.
Ruling out neutrinos
The transmissions were caught from 30 degrees below the ice surface- a phenomenon quite uncommon for neutrinos. Stephanie Wissel, an astrophysicist at Penn State University and part of the team, said in her results journal, “It’s an interesting problem because we still don't actually have an explanation for what those anomalies are, but what we do know is that they're most likely not representing neutrinos.”
According to the team’s calculations, neutrino signals are highly unlikely to be detected despite their widespread availability. The signals would have had to pass through thousands of kilometers of rock before being recorded, which makes the possibility incredibly low. “You have a billion neutrinos passing through your thumbnail at any moment, but neutrinos don't really interact. So, this is the double-edged sword problem. If we detect them, it means they have traveled all this way without interacting with anything else. We could be detecting a neutrino coming from the edge of the observable universe,” Wissel added.
Possible alternatives
Given its secluded location and minimal interference from other signals, the Antarctic was picked as the backdrop of this study. Speaking about how the ANITA works, Wissel said, “We have these radio antennas on a balloon that flies 40 kilometers above the ice in Antarctica. We point our antennas down at the ice and look for neutrinos that interact in the ice, producing radio emissions that we can then sense on our detectors.”
{{/usCountry}}Given its secluded location and minimal interference from other signals, the Antarctic was picked as the backdrop of this study. Speaking about how the ANITA works, Wissel said, “We have these radio antennas on a balloon that flies 40 kilometers above the ice in Antarctica. We point our antennas down at the ice and look for neutrinos that interact in the ice, producing radio emissions that we can then sense on our detectors.”
{{/usCountry}}After cross-referencing the data picked up by ANITA with two other independent detectors namely the IceCube Experiment and the Pierre Auger Observatory, the team found that the results didn’t match. The signal has now been described as “anomalous” and confirmed not to be a result of neutrino activity.
“My guess is that some interesting radio propagation effect occurs near ice and also near the horizon that I don't fully understand, but we certainly explored several of those, and we haven't been able to find any of those yet either,” Wissel noted. “So, right now, it's one of these long-standing mysteries, and I'm excited that when we fly PUEO, we'll have better sensitivity. In principle, we should pick up more anomalies, and maybe we'll actually understand what they are. We also might detect neutrinos, which would in some ways be a lot more exciting.”
Several plausible theories to explain the incident have been provided with some suggesting the existence of dark matter and unknown radio wave behavior due to the ice and proximity to the horizon. However, no concrete answer has been reached.
By Stuti Gupta