February 2023, The cosmic particle detector in the depths of the Mediterranean recorded the arrival of neutrinos, whose energy was about 20 to 30 times higher than any other neutrinos recorded previously. The particle is marked KM3-230213A and has a calculated energy of 220 Petaelectronvolts (PEV), much larger than the 10 PEV of the most energetic neutrinos before. This discovery has excited physicists, but also raised many questions.
Neutrinos are the most abundant particles in the universe in mass. They are elementary particles, meaning they don’t break down into smaller components and are therefore small and lightweight. In fact, they are the lightest of all subatomic particles with mass. Neutrinos also have no charge (unlike electrons, another type of elementary particles, which is negative). As a result, few neutrinos interact with other matter. They usually go through it directly without changing it. In fact, since you started reading this, trillions of neutrinos will pass through your body. Therefore, neutrinos are sometimes called “ghost particles.”
For particle physicists, this anomaly energy-based neutrino can only be explained in two ways: KM3-230213A is evidence of cosmic processes, which may have never been seen before, and may change our understanding of neutrinos. Or it is a disappointing measurement error. Researchers quickly began to work hard to find out which explanations were correct.
Now there seems to be an answer. A comprehensive study published in the journal Physical Review X compared the data from KM3-230213A with an information database of other ghost particles that have been detected. After analyzing the available data, scientists believe that this extraordinary ultra-energy neutrino is not a statistical fantasy.
But where does it come from?
Just as rocks cannot describe the nature of a mountain, only 220 PEV neutrinos are useless for explaining the phenomenon that produces it. As the paper admits, with the available information, it is impossible to “get definite conclusions about observations suggesting new ultra-high energy components in this spectrum.”
However, if there are other records of energy-like neutrinos, this will be done by suggesting substantial progress in the existence of other previously invisible phenomena. “This could mean we see cosmic neutrinos for the first time, generated when cosmic rays interact with cosmic microwave backgrounds, or perhaps point to a new type of astrophysical source,” the study said.
The energy of neutrinos in 2023 also suggests that it may be emitted by one of the powerful cosmic accelerators we realize in the universe: a gamma-ray burst or supernova, or perhaps a relativity jet, a beam of plasma emitted from near a black hole. In contrast, many of the neutrinos detected on Earth are atmospheric neutrinos, produced by the effects of cosmic rays hitting atoms in the Earth’s atmosphere, and have much less energy. They are the same particles, but their origin may affect their energy.
Different branches of neutrinos are scientifically used and studied for different reasons. Since neutrinos pass through the universe without being deflected or absorbed, valuable information about very distant cosmic events can be provided. Some scientists consider them “reporters from the universe” who travel to Earth from time to time with their lost data.
This story originally appeared in Wired enespañol and has been translated into Spanish.
