Scientists are trying to solve a mystery of a decade when determining the identity of anomalous signs detected under the Ice in Antarctica.
The strange radio waves emerged during a search for another unusual phenomenon: high energy cosmic particles known as neutrinos. Reaching the land of the more distant regions of the cosmos, neutrinos are often called “Ghostic” Because they are extremely volatile, or vaporous, and can cross any kind of matter without change.
In the last decade, researchers have conducted multiple experiments using vast extensions of water and ice designed to look for neutrinos, which could clarify the most energetic particles in the universe. One of these projects was the Antarctic Impulsive Transient Antenna Experiment, or Anita, which launched balloons carrying instruments on Antarctica between 2006 and 2016.
It was during this search that Anita detected anomalous radio waves that didn’t seem to be neutrinos.
The signs came from under the horizon, suggesting that they had crossed thousands of kilometers of rock before reaching the detector. But radio waves should have been absorbed by the rock. The Anita team believed that these anomalous signs could not be explained by the current understanding of particle physics.
Observations and follow -up analyzes with other instruments, including one recently performed by the Pierre Auger Observatory in Argentina, could not find the same signs. Pierre Auger collaboration results were published in Physical Review Letters in March.
The origin of anomalous signs remains uncertain, said the co -author of the study Stephanie Wissel, associate professor of physics, astronomy and astrophysics at Pennsylvania State University.
“Our new study indicates that such (signs) were not seen by an experiment, such as the Pierre Auger Observatory,” said Wissel. “So this does not indicate that there is a new physics, but more information to add to the story.”
Larger and more sensitive detectors may be able to solve the mystery, or finally prove whether anomalous signs have been a chance, while they continue to search for neutrine enigmatic and their sources, scientists say.
Detection of researchers allows them to track them to their sources, that scientists believe they are mainly cosmic rays that reach the atmosphere of our planet.
The most energetic particles in the universe, cosmic rays are mainly composed of protons or atomic nuclei, and are released through the universe because whatever produces them is such a powerful particle accelerator that it overshadows the capabilities of the large Hawk collier. Neutrinos could help astronomers better understand cosmic rays and what throws them through the cosmos.
But neutrinos are difficult to find because they have almost no mass and can go through the most extreme environments, such as stars and whole, unchanged galaxies. They, however, interact with water and ice.
Anita is designed to look for the highest energy neutrinos in the universe, in higher energies than those already detected, Justin Vandenbrouke, Associate Professor at Wisconsin University, Madison, said. The experimental radio antennas look for a short pulse of radio waves produced when a neutrino collides with an atom on antarctic ice, leading to a lower -energy particle waterfall, he said.
During their flights, Anita found High energy sources of ice particlesa kind of inverted shower of cosmic rays. The detector is also sensitive to ultra-high energy cosmic rays that fall on the earth and create a radio explosion that acts as a radio wave flashlight beam.
When Anita observes a cosmic radius, the flashlight beam is actually a explosion of radio waves lasting a billionth of a second that can be mapped as a wave to show how it reflects on ice.
Twice on their Anita flight data, the experiment’s original team has detected signs by rising through the ice at a much more acute angle than expected by any model, making it impossible to track the signals to their original sources.
“The radio waves we detected almost a decade ago were in really steep angles, such as 30 degrees below the ice surface,” Wissel said.
Neutrinos can travel through a lot of matter, but not through the entire land, Vandenbrouke reinforced.
“They are expected to arrive a little below the horizon, where there is not much land to be absorbed,” he wrote in an email. “Anita’s anomalous events are intriguing because they seem to come well below the horizon, so neutrinos would have to travel through much of the earth.”
“This is not possible according to the standard model of particle physics.”
The Pierre Auger collaboration, which includes hundreds of scientists around the world, analyzed more than a decade of data to try to understand the anomalous signs detected by Anita.
The team also used their observatory to try to find the same signs. The Auger Observatory is a hybrid detector that uses two methods to find and study cosmic rays. A method depends on the detection of high energy particles as they interact with water in earth surface tanks, and the other potential tracking interactions with ultraviolet light in the high atmosphere of our planet.
“The Auger Observatory uses a very different technique to observe ultra-high energy cosmic ray showers, using the secondary glow of loaded particles as they cross the atmosphere to determine the direction of the cosmic radius that began it,” said Peter Gorham, professor of physics at the University of Hawaii in Mānoa. “When using computational simulations of what such particle shower would seem if they had behaved like Anita’s anomalous events, they can generate a kind of model for similar events and then search for their data to see if something similar appears.”
Gorham, who was not involved with the new research, designed the Anita experiment and conducted other research to understand more about anomalous signs.
Although the Auger Observatory has been designed to measure descendant particle showers produced in the ultra-high energy cosmic rays, the team redesigned their data analysis to look for ascending atmospheric showers, Vandenbrouke said. Vandenbrouke did not work in the new study, but was the reviewer of the same before the publication.
“Auger has a huge area of collection for such events, larger than Anita,” he said. “If Anita’s anomalous events are produced by any particle traveling through the earth and then producing ascending showers, the auger should have detected many of them, and did not detect.”
A separate follow -up study using the Icecube experiment, which has deeply incorporated sensors into antarctic ice, also sought anomalous signs.
“Since the icecube is very sensitive, if Anita’s anomalous events were neutrinos, we would have detected them,” wrote Vandenbrouke, who acted as a colleyage of the Icecube neutrinic sources working group between 2019 and 2022.
“It’s an interesting problem because we don’t have a real explanation for what these anomalies are yet, but what we know is that they probably don’t represent neutrinos,” Wissel said.
Curiously, a different type of neutrino, called neutrino tauIt is one of the hypotheses that some scientists have presented as the cause of anomalous signs.
Tau neutrinos can regenerate. When they decline in high energies, they produce another tau neutrino, as is a particle called lepton tau – similar to an electron, but much heavier.
But what makes the neutrino scenario tau very unlikely is the inclination of the angle connected to the signal, Wissel said.
“You expect all these Tau neutrinos to be very, very close to the horizon, perhaps one to five degrees below the horizon,” Wissel said. “These are 30 degrees below the horizon. There is simply too much material. They would really lose a lot of energy and would not be detectable.”
In the end, Gorham and the other scientists have no idea of the origin of Anita’s anomalous events. So far, no interpretation corresponds to the signs, which continues to attract scientists to try to solve the mystery. The answer, however, may be close.
Wissel is also working on a new detector, Payload for Ultra-High Energy Observations or Pueo, which will flee Antarctica for a month from December. Bigger and 10 times more sensitive than Anita, Pueo can reveal more information about what is causing the anomalous signs detected by Anita, Wissel said.
“At the moment, it’s one of those longtime mysteries,” said Wissel. “I’m excited that when we fly Pueo, we’ll have better sensitivity.”
“In principle, we must be able to better understand these anomalies, which will contribute significantly to understanding our origins and, consequently, detecting neutrinos in the future.”
Gorham explained that Pueo, an acronym that refers to the Hawaiian owl, should have the necessary sensitivity to capture various anomalous signs and help scientists find an answer.
“Sometimes you need to go back to the zero stake and really find out what these things are,” Wissel said. “The most likely scenario is that it is some common physical phenomenon that can be explained, but we are knocking on every door to trying to find out what they are.”
