Detection was made 3,450 meters (2.1 miles) underwater

13/2/2025 6:15

Using an observatory under

construction deep beneath the Mediterranean Sea near Sicily,

scientists have detected a ghostly subatomic particle called a

neutrino boasting record-breaking energy in another important

step toward understanding some of the universe's most

cataclysmic events.



The researchers, part of the KM3NeT (Cubic Kilometre

Neutrino Telescope) Collaboration, believe the neutrino came

from beyond the Milky Way galaxy. They identified 12

supermassive black holes actively guzzling surrounding matter at

the center of distant galaxies as possible origination points,

though the neutrino may have arisen from some other source.



KM3NeT comprises two large neutrino detectors at the bottom

of the Mediterranean. One called ARCA - 3,450 meters (2.1 miles)

deep near Sicily - is designed to find high-energy neutrinos.

One called ORCA - 2,450 meters (1.5 miles) deep near Provence,

France - is designed to detect low-energy neutrinos.



The newly described "ultra-high energy" neutrino, detected

by ARCA in February 2023, was measured at about 120 quadrillion

electronvolts, a unit of energy.



It was 30 times more energetic than any other neutrino

detected to date, a quadrillion times more energetic than

particles of light called photons and 10,000 times more

energetic than particles made by the world's largest and most

powerful particle accelerator, the Large Hadron Collider near

Geneva.



"It's in a completely unexplored region of energy," said

physicist Paschal Coyle of the Marseille Particle Physics

Centre (CPPM) in France, one of the leaders of the research

published on Wednesday in the journal Nature.



"The energy of this neutrino is exceptional," added

physicist Aart Heijboer of the Nikhef National Institute for

Subatomic Physics in the Netherlands, another of the

researchers.



Neutrinos offer scientists a different way to study the

cosmos, not based on electromagnetic radiation - light. Many

aspects of the universe are indecipherable using light alone.



Neutrinos are electrically neutral, undisturbed by even the

strongest magnetic field, and rarely interact with matter. As

neutrinos travel through space, they pass unimpeded through

matter - stars, planets or anything else.



That makes them "cosmic messengers" because scientists can

trace them back to their source, either within the Milky Way or

across galaxies, and thus learn about some of the most energetic

processes in the cosmos.



"Neutrinos are ghost particles. They travel through walls,

all the way through the Earth, and all the way from the edge of

the universe," Coyle said. "Neutrinos have zero charge, zero

size, almost zero mass and almost zero interaction. They are the

closest thing to nothing one can imagine, but nevertheless they

are key to fully understanding the universe."



Other high-energy cosmic messengers zipping through space

are not as reliable. For instance, the path of cosmic rays gets

bent by magnetic fields, so they cannot be traced back to their

place of origination.



Detecting neutrinos is not simple, requiring large

observatories located deep underwater or in ice. These mediums

offer an expansive and transparent volume where a passing

neutrino may interact with a particle, producing a flash of

light called Cherenkov radiation.



The researchers concluded that the one spotted at ARCA -

which was a type of neutrino called a muon - was of cosmic

origin based on its horizontal trajectory and the fact that it

had traversed through about 140 km (87 miles) of rock and

seawater before reaching the detector.



The KM3NeT detectors are still under construction and have

not yet reached their full capabilities.



Neutrinos are produced through various astrophysical

processes at various energy levels. For instance, low-energy

neutrinos are born in nuclear fusion processes inside stars.



High-energy neutrinos arise from particle collisions

occurring in violent events such as a black hole greedily eating

infalling matter or bursts of gamma rays during the explosive

deaths of stars. They also can be produced by interactions

between high-energy cosmic rays and the universe's background

radiation.



The study of neutrinos is still in its formative stages.



"So why it matters? It's basically just trying to understand

what is going on in the cosmos," Heijboer said.