Just a few months back, researchers at The IceCube Neutrino Observatory (IceCube) in Antarctica, reported that after years of rigorous data collection, they still couldn’t be certain of what first caused the mysterious “Fermi Bubbles” spewing from the center of the Milky Way. Now, the IceCube scientists say they’ve found another anomaly in nature, and this one is so strange it may require new physical laws in order to be explained.
New Scientist picked up news of the strange anomaly, which was described in a paper recently published in The Astrophysical Journal. The IceCube press release describing the paper notes that “extremely high-energy neutrinos” (emphasis theirs) were detected by the team’s Antarctic Impulsive Transient Antenna (or ANITA), and apparently traveled right through Earth, despite the fact that they shouldn’t have.
? New IceCube paper submitted to ApJ! ?
ANITA, another Antarctic neutrino experiment, has detected some very strange signals. In this analysis, IceCube scientists found that these signals cannot be explained with Standard Model physics…
— IceCube Neutrino Observatory (@uw_icecube) January 8, 2020
While less energetic neutrinos are able to pass through all of Earth’s matter without issue, these extremely high-energy neutrinos should’ve behaved more like “bulls in a china shop” according to one of the lead authors of the paper, Alex Pizzuto of the University of Wisconsin–Madison. “It’s commonly said that neutrinos are ‘elusive’ or ‘ghostly’ particles because of their remarkable ability to pass through material without smashing into something,” Pizzuto says in the press release, “But at these incredible energies, neutrinos… become much more likely to interact with particles in Earth.”
Scientists have tried explaining the phenomenal ability for these extremely high-energy neutrinos to pass through Earth undisturbed, but so far explanations within the bounds of the Standard Model of physics—the theory that describes three of the four known fundamental forces of the universe—have failed.
A look at ANITA on the ground. NASA
To determine the source of the anomalous neutrinos, the researchers took eight years of data collected by IceCube and cross referenced it with the theoretical source location for the anomalous extremely high-energy neutrinos detected by ANITA. (ANITA is tuned to detect higher-energy neutrinos and is able to do so thanks to the fact that it floats in the atmosphere, suspended from a balloon.) No lower-energy neutrinos that would’ve come from the same source location as those detected by ANITA were found, however, meaning that they must’ve not come from “an intense point source.” This is especially bizarre because, as Anastasia Barbano, another lead author of the paper, notes, “the odds of ANITA seeing an event and IceCube not seeing anything are [incredibly] slim.”
?Cannot be explained by ???????? ????? physics?
— Alex Pizzuto (@ajpizzuto) January 14, 2020
This all means that the anomalous extremely high-energy neutrinos detected by ANITA somehow zipped through Earth without running into anything, even though they should have, and also have no apparent source, which other neutrinos usually do. Because of these two mysteries, the IceCube scientists are now looking to new, exotic physics to explain the unexplainable. Once they’re certain these anomalous neutrinos aren’t, in fact, an error with their detectors, it seems that new physics will be their last resort for finding an explanation. “Our analysis ruled out the only remaining Standard Model astrophysical explanation of the anomalous ANITA events,” Pizzutor says in the IceCube press release, adding that “if these events are real and not just due to oddities in the detector, then they could be pointing to physics beyond the Standard Model.”
What do you think about these anomalous extremely high-energy neutrinos? Do you think new, exotic physics will be necessary to describe this phenomenon, or is there a Standard Model explanation that these researchers have overlooked? Give us your ultra-high energy opinions in the comments!
Feature image: NASA