KM3NeT has recently detected cosmic neutrinos with high energies of petaelectronvolts. This exceeds the data recorded by IceCube and Pierre Auger. New questions arise regarding cosmic background radiation, cosmic rays, and even gamma-ray bursts. Regarding theories about their origin, the Milky Way takes second place. Thus, the discovery led to the creation of muons, thanks to photons that have enabled a more exhaustive study.
Detection of a cosmic neutrino
The detection of a cosmic neutrino that crushed into Earth with an non-expected energy level is not a glitch or a mistake, but a real detection of a real particle.
In February 2023, a detector called KM3NeT, located deep under the Mediterranean Sea, picked up a signal that seemed to reveal a neutrino with a record-shattering energy of 220 petaelectronvolts (PeV). For reference, the previous record was just 10 PeV.
Currently, a new study of all the data on and around the event, designated KM3-230213A, not only holds up the conclusions that the signal was caused by a 220-PeV neutrino, but adds to the mystery about where the heck in the Universe it came from.
“The patterns of light detected for KM3-230213A show a clear match to what is expected from a relativistic particle crossing the detector, most likely a muon, ruling out the possibility of a glitch,” the KM3NeT Collaboration told ScienceAlert.
Neutrinos are all aloing the Universe
Neutrinos are really usual in the Universe – among the most abundant particles out there, generated by energetic circumstances, such as stellar fusion, or supernova explosions. Nevertheless they have no electric charge, their mass is close to zero, and they almost interact with other particles they encounter.
Hundreds of billions of neutrinos are streaming through your body right at this moment, just passing on through like ghosts. That’s the main reason they’re affectionately known as ghost particles.
This avoidant particle personality poses something of a issue: it makes neutrinos almost not possible to detect. Every now and again, nevertheless, a neutrino smacks into another particle, an event that produced a small shower of particles such as muons and photons – particles of light. This shows a very faint glow that the right detector can pick up.
Everything you must know abot KM3NeT
KM3NeT is just such a detector array. It’s submerged 3,450 meters (11,320 feet) under the surface of the ocean, a depth at which no sunlight can pass through. In such total darkness, neutrino events shine like tiny beacons.
This is what led to the detection of KM3-230213A, but since other detectors operating far longer have come nowhere close to such a high energy detection, some uncertainty left behind.
The KM3Net collaboration explained that given that other experiments, IceCube and Auger in particular, have been operating for more than a decade and have before performed looks for for ultra-high-energy neutrinos but have not detected one so far. In addition, they are investigating the possibility that the neutrino observed by KM3NeT is the first such neutrino observed,.
“We find that, despite a rather low probability of happening – approximately 1 in 100 chance – it is possible that the only event seen so far is in KM3NeT and not in IceCube and Pierre Auger; therefore, the three measurements do not disagree.”
The profesionals also studied how KM3-230213A fits into the bigger neutrino picture – how many neutrinos are streaming through the Universe, and the distribution of energies. The increasing of the 220-PeV neutrino results in more coherent predictions of neutrino behavior.
At the end, the paper studied whether KM3-230213A proposes the presence of a recent component or process that produces ultra-high-energy neutrinos, compared to the relatively known processes under the rest of the neutrinos detected to date.
The results are not clear
Alas, the study was not able to determine whether there’s a recent component or not. Possible origins of the neutrino still take into account ejection from the extreme environment of a galactic center, the gamma-ray bursts emitted by exploding stars, or an interaction with the cosmic microwave background.
One subject that scientists do have in mind, though, is that it’s very, very unlikely that the neutrino originated within the Milky Way galaxy. So wherever it’s from, KM3-230213A was born somewhere extreme and very for away. Work is nowadays underway to try and refine the neutrino’s trajectory, to hopefully come closer to tracing its origin point. So we’re far from hearing the last from KM3-230213A.
The paper has been published in Physical Review X.
