The ARCA detector of the KM3NeT underwater neutrino telescope, located deep in the Mediterranean Sea near Sicily, registered the passage of a neutrino with an unprecedented energy of 220 peta-electronvolts (PeV). The event marked the detection of the most energetic neutrino ever observed, surpassing previous records by more than 100 times.
Neutrinos are tiny, electrically neutral elementary particles that zoom across the universe at nearly the speed of light, interacting very weakly with matter. As a result, they are difficult to detect. Diário de Notícias reports that neutrinos are so elusive that their chance of interacting with matter is akin to flipping 75 heads in a row on a fair coin.
The KM3NeT project, still under construction, is divided into two sites: ARCA, dedicated to high-energy astronomy at a depth of 3,450 meters off the coast of Sicily, Italy, and ORCA, optimized for studying neutrino properties at a depth of 2,450 meters off Toulon, France. These detectors utilize seawater as an interaction medium to detect high-energy neutrinos.
Despite operating at just 10% of its planned configuration, the KM3NeT instrument managed to capture this event.
Neutrinos act as celestial messengers, gliding silently from cosmic collisions and carrying information from the most remote places in the universe. They provide insights into extreme phenomena like supernova explosions and gamma-ray bursts.
The exact origin of this super-energetic neutrino remains unknown. Scientists speculate that it may have formed amid cosmic cataclysms such as supermassive black holes, supernovae, or gamma-ray bursts.
The detection of this neutrino is important not only because of its unprecedented energy but also because it opens new avenues in astronomy. "The detection of a cosmic neutrino of this magnitude opens a new chapter in astronomy and a new window of observation of the universe," stated Paschal Coyle, spokesperson for KM3NeT, according to a report by ANSA.
The KM3NeT telescope comprises two detectors, ARCA and ORCA, utilizing seawater to capture Cherenkov light—a bluish glow produced when neutrinos interact with water molecules. This method allows scientists to detect these particles.
Neutrinos are produced in environments including during violent cosmic events. Phys.org notes that ultra-high-energy neutrinos can escape dense regions that produced them and travel in a straight line through the universe, making them excellent probes of distant astrophysical phenomena.
The powerful neutrino, designated KM3-230213A, was detected after traveling across the cosmos. Its journey was undisturbed by galaxies, stars, or other matter, arriving at Earth with high energy.
The detection was the result of a collaborative effort. The KM3NeT Collaboration includes over 360 scientists from 68 institutions in 21 countries.
Researchers are continuing to investigate possible sources of the neutrino. Potential sources include blazars, which are energetic cores of active galactic nuclei powered by supermassive black holes. Blazars emit beams of high-energy particles and light pointed directly at Earth, making them plausible candidates.
"We get excited, as physicists, when there's a bit of drama," said Éric Thrane, an astrophysicist at Monash University who was not involved in the research, according to ABC News Australia.
This article was written in collaboration with generative AI company Alchemiq