Earlier this year, an underwater detector in the Mediterranean Sea has found the most energetic neutrino to date. And scientists always talk about it because, well, this discovery could really be a big problem. Not only is this neutrino, also known as “ghost particle”, could have flew a gust of gamma rays or a supermassive black hole, but it could also have been produced by an ultra-powerful cosmic radius interacting with the cosmic microwave (CMB).
This last song we will arrive soon, could be enormous. In addition, the detector that has identified this particle is not even completely constructed yet – once assembled, who knows what he can accomplish. “We are delighted to have observed this event and we are hungry and curious for more,” said Km3net spokesperson, Paul de Jong from Amsterdam, Space.com
For a background, the neutrino was detected on February 13, 2023 by the European Union Km3The neutrino telescope kilometer cube. Neutrinos are ghostly particles because they have very little mass and rarely interact with other forms of matter, which makes them very difficult to detect. Billions of neutrinos cross your body every second, but you cannot say it. Scientists should be patient to even locate a neutrino.
Modern neutrinos detectors are placed in water, and in particular in darkness. Sometimes this water is maintained in a reservoir, as was the case with the Sudbury neutrinos observatory in Canada, as well as with the super-kamiokande in Japan. Other times, this water is frozen in the ground, as in the case of NEUTRINOS Observatory Icecube at the South Pole. But it is also possible for neutrinos detectors to be literally immersed in the sea, as is the case with KM3NET, which extends up to 2.17 miles (3.5 kilometers) under the waves.
The reason why water is so important is that sometimes a neutrinos will interact with a molecule of water. The energies involved can be so large that the collision breaks the separate water molecule into a pile of nuclei and girl particles, especially muons. The muons travel quickly, almost as fast as light In a vacuum, and certainly faster than the light through the water – the water refraction index slows around 738,188,976 feet per second (225,000,000 meters per second) against 983,571,056 feet per second (299,792,458 meters per second) in a vacuum. Because the muons travel faster than the light in the water, they give off the equivalent of a sound boom in the form of a lightning of light. This light is called Cherenkov radiation.
KM3NET consists of two detectors. The first, called Orca, is 8,038 feet (2,450 meters) deep off the coast of France and is designed to study how neutrinos oscillate between different types of neutrinos. The other, alias the detector which spotted the new energetic neutrino – which was cataloged under the name of KM3-230213a – is called Arca and is located off the coast of Sicily.
Arca and Orca are still under construction. Once finished, Arca will include 230 lines of vertical detection descending into the sea. Each will be doubled with 18 optical modules containing 31 photomultiplier tubes which can identify flashes of Cherenkov radiation in the dark at these depths. As Arca detected the KM3-230213A, only 21 of its detection lines were in service.
The Arca Muon detected had an energy of 120 PEV (1,000 Billions, or Quadrillion, electrolves), which implies the neutrino that produced it must have a record energy of 220 PEV. These are 100 quadrillions more energetic than visible light photons, and 30 times more energetic than the neutrinos which maintained the previous energy record.
The muons can travel several kilometers through the sea before being absorbed, and Km3net has detected the muon traveling horizontally rather than directly to the seabed.
“The horizontal direction on the muon is very relevant,” said Jong.
Muons can also be trained in cosmic ray spallation, in which a cosmic radius between The atmosphere of the earth And collided with a molecule or an atom, crushing it in a shower of subatomic particles. The muons formed in this way can either reach the surface or enter the ocean while traveling directly – not horizontally. For having moved horizontally, the muon must have in place “was created near the detector, and the only realistic scenario is that it was created by a high energy neutrino,” said Jong.
A 220 PEV neutrino is unprecedented. No environment or object known in our Milky Way Galaxy Could have produced neutrinos with as much energy. This means that its origin must be extragalactic, perhaps created in the violence of an exploding star and producing a gust of gamma raysor a Supermassive black hole Ripping has star or a cloud of lamb gas with its titanic gravitational tide forces. Because neutrinos are not deflected by magnetic or gravity fields, their travel management brings back to their source.
“Muon’s management is almost identical to the direction of the original Neutrino, so we can play the game to bring it back to its cosmic origin,” said Jong.
This origin is somewhere in the direction of the constellation Orion, the hunter. However, although there are many active galaxies with supermassive black holes in this region, none of them brought an activity at the time which could explain the neutrino, and a gapma gamma was not detected in this direction at the time.
But another intriguing possibility is that km3-230213a is the first “cosmogenic” neutrino to discover, produced when an ultra-high cosmic radius crashes in a photon belonging to Cosmic microwave backgroundwhich is the residual light released 379,000 years after Big Bang.
It would take an extremely energetic cosmic radius to be able to produce a neutrino as km3-230213a. Cosmic rays greater than 100,000 PEVs were detected by the Pierre Auger observatory in Argentina. Their origins are uncertain, but, in theory, each time such a cosmic ray meets a CMB photon, the collision can produce neutrinos as energetic as km3-230213a.
The greater the energy of the cosmic rays, the greater the transverse section of its interaction, which means that it is more likely to interact with CMB photons. The constant interactions between the cosmic rays and the CMB photons slow down the cosmic ray, limiting their kinetic energy. This is called the Greisen limit – Zatsepin – Kuzmin (Gzk).
The possibility of a cosmogenic neutrinos excites Jong. “It would be the very first observation of a cosmogenic neutrino, and it would be the first confirmation of the Gzk cut outside the cosmic rays loaded-and even there, the proof is ambiguous,” he said.
In addition, the energy of cosmogenic neutrinos can reveal the properties of these ultra-high energy cosmic rays. This parameter is the key to discovering whether such phenomena are made protons or heavier atomic nuclei – and, therefore, which produces them. Although km3-230213a is the only extremely high energy neutrino detected by km3net, there will undoubtedly be much more passage Earth which are not detected. Is the early detection of KM3NET with Arca Bode well able to detect these neutrinos more regularly?
“We certainly hope!” said of Jong. “But realistically, other experiences such as Icecube have taken data for longer and have not observed such an event, so we could have been lucky.”
The discovery was described in an article published on February 12 in the review Nature.