Russian researchers have now traced the source of some ultra-high-energy neutrinos — radio flares from active quasars– according tomedia New Atlas. Neutrinos are elementary particles with neutral charges with almost no mass. They are very common and occur when nuclear reactors and weapons, the sun, supernovae and cosmic rays interact with the Earth’s atmosphere.
But some of them are accelerated into extremely high levels of energy in deep air, and how and where this happens remains a mystery. The mystery is the target of a new study by researchers at the Moscow Institute of Physics and Technology (MIPT), the Russian Academy of Sciences and the Max Planck Institute.
Although neutrinos are common, they are difficult to study. This is because they do not interact with other matter much and can easily cross the entire planet. But every once in a while, one particle interacts randomly with another, and a special detector can capture the signal. To protect them from outside interference, neutrino detectors are usually built deep underground, underwater or under ice. As a result, other particles deflect on or near the earth’s surface, while neutrinos pass directly through.
In this case, the team used data from the IceCube Neutrino Observatory, a neutrino observatory buried 2 kilometers (1.2 miles) under ice in Antarctica. They are looking for neutrinos with 200 trillion electron volts or more.
Their hypothesis is that high-energy neutrinos are generated during radio flares in quasars. When matter falls into a black hole, protons are sometimes accelerated and ejected into space to become high-energy neutrinos. Although neutrinos from quasars have been detected before, they are thought to always be accompanied by gamma-ray bursts. The team in the new study suspects they may have been created in radio flares.
To find out, the researchers analyzed 50 neutrino events collected by IceCube and compared the data with radio telescopes around the world that measured quasars. In particular, they used the Russian radio telescope RATAN. Sure enough, they found that when neutrinos hit the Earth, radio flares with frequencies greater than 10GHz were often recorded from certain quasars.
“At first, the results seemed ‘too good’, but after careful analysis of the data, we confirmed that neutrino events were clearly related to the signals picked up by radio telescopes,” said Study author Sergey Troitsky. “We examined this correlation based on years of observations by the RATAN telescope at the RAS Special Astrophysical Observatory, and the probability of randomness was only 0.2%. This has been quite successful in neutrino astrophysics, and our findings now require theoretical explanations. “
Now, the team plans to study exactly how quasars produce neutrinos and re-examine the initial findings.
The findings were published in the Astrophysical Journal.