STRANGE radio pulses detected roughly 25 miles (40km) above Antarctica could be the mark of a new cosmic particle, according to a new study.
This rare signal was first detected by the Antarctic Impulsive Transient Antenna (ANITA) in 2006, a series of tools floating over icy continent carried by balloons.
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The now-retired ANITA experiment aimed to detect ultra-high-energy (UHE) cosmic neutrinos – or “ghost particles” – and other cosmic rays as they rain down on Earth from space.
While ANITA usually picks up cosmic signals that bounce off the ice, this new radio pulse came from beneath the horizon and under the ice sheet.
Its orientation cannot currently be explained by particle physics, a study in the journal Physical Review Letters wrote.
A similar event was recorded in 2014, and it has continued to baffle scientists.
The mysterious radio waves were being emitted at a steep angle below the ice, suggesting they had to pass through thousands of miles of rock before reaching ANITA.
All those obstacles would typically leave a radio pulse too faint to be detectable – but not this signal.
“It’s an interesting problem, because we still don’t actually have an explanation for what those anomalies are,” ANITA team member and Penn State University researcher Stephanie Wissel said in a statement.
“What we do know is that they’re most likely not representing neutrinos.”
Scientists have ruled out neutrinos, the most common particle in the universe.
Neutrinos are unofficially known as “ghost particles” due to the fact that they don’t have any mass or carry any charge.
“You have a billion neutrinos passing through your thumbnail at any moment, but neutrinos don’t really interact,” added Wissel.
“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.”
Scientists suspected that a supernova erupting in space could have coughed a slew of neutrinos in Earth’s direction.
An international team of researchers attempting to solve the mystery conducted a series of simulations to see if the 2006 and 2014 events align with any significant cosmic events, with data from the the Pierre Auger Observatory in Argentina.
There was a supernova that aligned with the signals captured in 2014, but not the 2006 event.
So there is no clear indication that this cosmic event is what caused the bizarre radio waves.
What scientists have done, however, is narrow down their set of explanations.
“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,” said Wissel.
“So, right now, it’s one of these long-standing mysteries, and I’m excited that when we fly [Payload for Ultrahigh Energy Observations], 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.”
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