Where do neutrinos come from?

US, WASHINGTON (ORDO NEWS) — Russian astrophysicists have come close to determining the origin of high-energy neutrinos from space. The team compared data on elusive particles collected by the IceCube Antarctic Neutrino Observatory and long electromagnetic waves measured by radio telescopes. It turned out that cosmic neutrinos are associated with flares in the centers of distant active galaxies, which are believed to contain supermassive black holes.

When matter falls toward the black hole, some of it accelerates and is thrown into space, which leads to the appearance of neutrinos, which then move through the universe at almost the speed of light.

The study is published in the Astrophysical Journal and is also available in the arXiv preprint repository.

Neutrinos are mysterious particles, so tiny that researchers do not even know their mass. They easily pass through objects, people, and even entire planets. High energy neutrinos are created when protons accelerate almost to the speed of light.

Russian astrophysicists have focused on the origin of ultrahigh-energy neutrinos at 200 trillion electron-volts or more. The team compared the measurements of an IceCube object buried in Antarctic ice with a large number of radio observations. It was found that elusive particles occur during radio frequency bursts in the centers of quasars.

Quasars are sources of radiation at the centers of some galaxies. They consist of a massive black hole that absorbs matter floating in the disk around it and spews extremely powerful jets of super-hot gas.

“Our results show that high-energy neutrinos are generated in the active nuclei of the galaxy, especially during radio flares. Since both neutrinos and radio waves travel at the speed of light, they reach the Earth at the same time, ”said the first author of the study, Alexander Plavin.

Plavin – Ph.D. P. N. Lebedeva of the Russian Academy of Sciences (RAS) and the Moscow Institute of Physics and Technology. Thus, he is one of the few young researchers who obtained results of this level at the beginning of his scientific career.

Neutrinos come from where no one expected

After analyzing about 50 neutrino events detected by IceCube, a team of scientists showed that these particles come from bright quasars visible by a network of radio telescopes around the planet. The network uses the most accurate method for observing distant objects in the radio range: a very long basic interferometry.

This method, in fact, creates a giant telescope, placing many antennas around the globe. Among the largest elements of this network is the 100-meter telescope of the Max Planck Society in Effelsberg.

In addition, scientists have hypothesized that neutrinos occurred during radio outbreaks. To test this idea, physicists studied the data of the Russian RATAN-600 radio telescope in the North Caucasus. This hypothesis turned out to be very plausible, despite the widespread assumption that high-energy neutrinos should arise together with gamma rays.

“Previous studies of the origin of high-energy neutrinos searched for their source right in the spotlight. We thought that we would experience an unconventional idea, albeit without much hope of success. But we were lucky, ”says Yuri Kovalev from the Lebedev Institute, Moscow Institute of Physics and Technology and the Max Planck Institute for Radio Astronomy. “Long-term observations from international radio telescopes have made this a very interesting discovery, and the radio range has been decisive in determining the origin of neutrinos.”

“At first, the results seemed too good to be true, but after a thorough re-analysis of the data, we confirmed that neutrino events are clearly related to the signals received by radio telescopes,” added Sergey Troitsky of the Institute for Nuclear Research of the Russian Academy of Sciences.

“We tested this association based on long-term observations of the RATAN telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The probability that the results will be random is only 0.2%. This is very successful for neutrino astrophysics, and our discovery now requires theoretical explanations.”

The group intends to double-check the results and find out the mechanism of the origin of neutrinos in quasars using data from the Baikal-GVD, an underwater neutrino detector in Lake Baikal, which is at the final stage of construction and is already partially operational.

The so-called Cherenkov detectors used to detect neutrinos – including IceCube and Baikal-GVD – rely on a large mass of water or ice as a means of maximizing the number of neutrino events and preventing accidental triggering of sensors. Of course, continuous observations of distant galaxies using radio telescopes are also crucial for solving this problem.

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