A 60 -year -old cosmic puzzle can finally have an answer

Could black holes help explain the origins of high-energy cosmic radiation?

The universe is filled with many forms of radiation and particles that can be detected here on earth. Among them are photons, which extend over the entire electromagnetic spectrum, the lowest radio waves with the most energetic gamma rays. Other examples include elusive neutrinos and cosmic rays, which both travel through space at almost the speed of light.

Interestingly, despite their name, the “cosmic rays” are not at all rays. The term has remained for historical reasons, but in reality, it is tiny particles, mainly atomic nuclei, which have been propelled to extraordinary energies somewhere in the cosmos. Scientists have long suspected that these particles come from some of the most extreme parameters in the universe, including black holes, explosive stars or neutron stars that turn (a type of dead star).

From time to time, however, cosmic rays are discovered with much greater energy than usual. These ultra-high energies particles have been intrigued since their identification for the first time in 1962, and their origins remain a mystery.

A team from the Norwegian University of Sciences and Technology (NTNU) can now be closer to the resolution of this sustainable puzzle in physics.

Supermassive black holes can be the cause

Foteini Oikonomou, associate professor in the NTNU physics department, is working on the case. In a recent article, she and her colleagues have a completely new and plausible explanation of this ultra-high influence.

The main author is the Domenik Ehlert doctorate in the same department. The team also includes the enrico peretti postdoctoral comrade from Paris Cité University. Their work focuses on the physics of astroparticles, which studies the relationship between the smallest particles of the universe and the greatest phenomena of the universe.

“We suspect that this high energy radiation is created by winds from supermassive black holes,” said Oikonomou.

But what does that mean?

Active black holes create winds

THE Milky Way is the district of the universe where you and I live. Our sunshine and solar system is part of this galaxy, as well as at least 100 billion other stars.

“There is a black hole called Sagittarius-A * located in the center of the Milky Way. This black hole is currently in a calm phase where it consumes no star, because there is not enough material nearby, “said Peretti.

This contrasts with the growing black, supermassive and active holes that consume the mass of our own sun each year.

“A small part of the material can be pushed by the force of the black hole before it is fired.

We have known these gigantic winds for about ten years. The winds of these black holes can affect galaxies. By exploding gases, they can prevent new stars from forming, for example. It is quite dramatic in itself, but Oikonomou and his colleagues looked at something else, much smaller, that these winds could be the cause of. “”

These powerful winds may accelerate the particles that create ultra-high energy radiation, “said Ehlert.

To understand this, we must also explain the atoms a little.

Atoms and huge amounts of energy

The atoms consist of a nucleus, made up of protons and neutrons. These particles are made up of quarks, but we do not need to enter it right now.

One or more electrons can be found around this nucleus in the so-called cloud.

“The ultra-high energy radiation consists of protons or atomic nuclei with energy up to 1020 volt electrons,” said Oikonomou.

If this number means nothing for you, you should know that in this context, it is an absolutely enormous amount of energy.

“A particle like this, which is smaller than atomContains about as much energy as a tennis ball when Serena Williams serves 200 kilometers per hour, “said Oikonomou.

It corresponds to approximately a billion times more energy than the particles created by researchers from the great collision of Hadrons in Switzerland and France.

Fortunately, these cosmic rays are destroyed by the earth’s atmosphere. When they reach the soil level, they are as harmless as all the other cosmic radiations that reach us on the surface of the earth.

“But for astronauts, cosmic influence is a very serious problem,” said Oikonomou.

The crews of airlines do not have to worry about this because they do not fly high enough.

“The main concern for astronauts is the low energy cosmic radiation produced by our own sun, because it is much more common. The rays we are studying are rare enough for it to be extremely unlikely that they are going through an astronaut,” she said.

Other suspects

Previously, the researchers sought to know if these high energy particles come from gusts of gamma rays, galaxies which create new stars at an extremely high rate, or from plasma Supermassive black holes flows.

However, Oikonomou and his colleagues have another hypothesis.

“All the other hypotheses are very good assumptions – these are all sources that contain a lot of energy. But no one provided that one of them is the source. This is why we decided to study the winds of the supermassive black holes,” said Ehlert.

Guilty? Maybe

So what do we really know? Are the winds that create high energy particles in cosmic radiation?

“Our answer is more a prudent” maybe “,” said Oikonomou.

This does not seem particularly dramatic. However, when researchers ask questions like this, they often feel a feeling of excitement and think “Yes, it may be the case!”, But that does not mean that this is the case in this case.

“We note that the conditions linked to these winds align particularly well with the acceleration of particles. But we are always unable to prove that it is specifically these winds which accelerate the particles behind high energy cosmic radiation,” said Oikonomou.

However, the model that researchers use can explain a specific aspect of these particles that we still do not understand. In a certain range of energy, particles have a chemical composition that other models cannot explain significantly.

“We can also test the model using neutrino experiences,” said Oikonomou.

However, this is something for a completely different article.

“In the years to come, we hope to collaborate with neutrinos astronomers to test our hypothesis,” said Oikonomou. Maybe they will then find more evidence, in one way or another.

Reference: “Ultra-elevated cosmic rays from ultra-rapid outputs of active galactic nuclei” by Domenik Ehlert, Foteini Oikonomou and Enrico Peretti, March 19, 2025, Monthly opinion from the Royal Astronomical Society.
DOI: 10.1093 / Mnras / Staf457

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