Nav: Home

Virginia Tech research provides new explanation for neutrino anomalies in Antarctica

June 09, 2020

A new research paper co-authored by a Virginia Tech assistant professor of physics provides a new explanation for two recent strange events that occurred in Antarctica - high-energy neutrinos appearing to come up out of the Earth on their own accord and head skyward.

The anomalies occurred in 2016 and 2018 and were discovered by scientists searching for ultra-high-energy cosmic rays and neutrinos coming from space, all tracked by an array of radio antennas attached to a balloon floating roughly 23 miles above the South Pole. Neutrinos are exceedingly small particles, created in a number of ways, including exploding stars and gamma ray bursts. They are everywhere within the universe and are tiny enough to pass through just about any object, from people to lead to buildings and the Earth itself.

The events were discovered by scientists at the ANITA experiment -- that's short for Antarctic Impulsive Transient Antenna, started in 2006 -- in the South Pole. Twice, ANITA scientists discovered radio signals mimicking highly energetic neutrinos seemingly coming upward out of the ground on their own accord. Scientists remain perplexed by the activity, with some 40 papers so far giving wildly different answers -- the pulses are neutrinos that passed unencumbered through the entire core of Earth and came out of the ground; the pulses are the long sought-after "fourth" neutrino known as the sterile neutrino; the mysterious "dark matter" of space is to blame; or this is an entirely unknown frontier of particle and/or astrophysics physics begging for a Nobel.

Ian Shoemaker, an assistant professor in the Department of Physics and the Center for Neutrino Physics, both part of the Virginia Tech College of Science, has a different, simpler explanation. In a recent paper published in the journal Annals of Glaciology, Shoemaker and several colleagues posit that the anomalies are not from neutrinos, but are merely unflipped reflections of the ultra-high-energy cosmic rays that arrive from space -- miss the top layer ice -- then enter the ground, striking deep, compacted snow known as firn.

"We think sub-surface firn is the culprit," said Shoemaker, adding that "firn is something between snow and glacial ice. It's compacted snow that's not quite dense enough to be ice. So, you can have density inversions, with ranges where you go from high density back to low density, and those crucial sorts of interfaces where this reflection can happen and could explain these events."

Shoemaker was joined on the paper by his former Ph.D. advisor, Alexander Kusenko of the University of California Los Angeles' Department of Physics and Astronomy; Andrew Romero-Wolf, a member of the ANITA team and a researcher at the California Institute of Technology's Jet Propulsion Laboratory; and four other researchers, including two glaciologists: Dustin Shroeder from Stanford University and Martin Siegert from Imperial College London.

Call it a case of Occam's razor (that's the centuries-old theory that the simplest solution in most likely the correct one, for those who skipped philosophy in college), but Shoemaker isn't railing ANITA. "Whatever ANITA has found, it is very interesting, but it may not be a Nobel prize-winning particle physics discovery." But he's not discounting that the so-called anomalies have no scientific merit. "ANITA still could have discovered something interesting about glaciology instead of particle physics, it could be ANITA discovered some unusual small glacial lakes."

Sub-glacial lakes were another consideration by Shoemaker and his team for the reflections. These lakes, deep underground, though, are too far spread apart according to current research, and hence are not the most likely explanation. But if there are far more lakes than previously known, this discovery would be a big win for scientists who study the landscape and interior of Antarctica. Shoemaker and his team suggest scientists purposefully blast radio signals into the areas where the anomalies occurred.

"I didn't know anything about them, but they really do exist," Shoemaker said of sub-glacier lakes in Antarctica. "There are lakes under the ice in Antarctica, and those would have the right reflective properties, but they're not widespread enough. Our idea is that part of the radio pulse from a cosmic ray can get deep into the ice before reflecting, so you can have the reflection without the phase flip. Without flipping the wave, in that case, it really looks like a neutrino."

Shoemaker added that, "When cosmic rays, or neutrinos, go through ice at very high energies, they scatter on materials inside the ice, on protons and electrons, and they can make a burst of radio, a big nice radio signal that scientists can see. The problem is that these signals have the radio pulse characteristic of a neutrino, but are appear to be traversing vastly more than is possible given known physics. Ordinary neutrinos just don't so this. But cosmic rays at these energies are common occurrences and have been seen by many, many experiments."

Virginia Tech

Related Neutrinos Articles:

Big answers from tiny particles
A team of physicists led by Kanazawa University demonstrate a theoretical mechanism that would explain the tiny value for the mass of neutrinos and point out that key operators of the mechanism can be probed by current and future experiments.
Physicists cast doubt on neutrino theory
University of Cincinnati physicists, as part of an international research team, are raising doubts about the existence of an exotic subatomic particle that failed to show up in twin experiments.
Exotic neutrinos will be difficult to ferret out
An international team tracking the 'new physics' neutrinos has checked the data of all the relevant experiments associated with neutrino detections against Standard Model extensions proposed by theorists.
Excess neutrinos and missing gamma rays?
A new model points to the coronoe of supermassive black holes at the cores of active galaxies to help explain the excess neutrinos observed by the IceCube Neutrino Observatory.
Where neutrinos come from
Russian astrophysicists have come close to solving the mystery of where high-energy neutrinos come from in space.
Where did the antimatter go? Neutrinos shed promising new light
We live in a world of matter -- because matter overtook antimatter, though they were both created in equal amounts when our universe began.
Strongest evidence yet that neutrinos explain how the universe exists
New data throws more support behind the theory that neutrinos are the reason the universe is dominated by matter.
Why didn't the universe annihilate itself? Neutrinos may hold the answer
New results from an experiment called T2K suggest that physicists are closer than ever before to answering a major mystery: Why didn't the universe annihilate itself in a humungous burst of energy not long after the Big Bang?
T2K insight into the origin of the universe
Lancaster physicists working on the T2K major international experiment in Japan are closing in on the mystery of why there is so much matter in the universe, and so little antimatter.
Radar and ice could help detect an elusive subatomic particle
A new study published today in the journal Physical Review Letters shows, for the first time, an experiment that could detect a class of ultra-high-energy neutrinos using radar echoes.
More Neutrinos News and Neutrinos Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Warped Reality
False information on the internet makes it harder and harder to know what's true, and the consequences have been devastating. This hour, TED speakers explore ideas around technology and deception. Guests include law professor Danielle Citron, journalist Andrew Marantz, and computer scientist Joy Buolamwini.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.