Scientists have revealed, for the first time, the origin of neutrinos

M. Weiss/CfA

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Cosmic rays consisting of highly energized and electrically charged particles continually bombard the Earth’s atmosphere.

These particles come from space and have traveled billions of light years. However, where do they come from? What is it that shoots them through the Universe with such great force? These questions have been among the most complex challenges in astrophysics for over a century.

An international research team, led by the University of Würzburg and the University of Geneva (UNIGE), is shedding light on one aspect of this mystery: it is thought that the neutrinos are born in blazars — galactic cores powered by supermassive black holes.

In 2017, Sara Buson and other researchers suggested that the blazar TXS 0506+056 would be a potential source of neutrinos.

This study sparked a scientific debate on whether there really is a link between blazars and high-energy neutrinos.

After taking this initial step, Buson’s team received funding from the European Research Council to start an ambitious research project in June 2021, according to the Tech Explorist.

The analysis of numerous signals (or “messengers”, for example neutrinos) from the Universe is necessary. The main objective is to understand the origin of astrophysical neutrinos, confirming whether blazars are really the first highly reliable source of high energy extra-galactic neutrinos.

The project has now had its first success. Scientists have confirmed that blazars can be confidently associated with astrophysical neutrinos with an unprecedented degree of certainty, according to the results of the new study. published no American Astronomical Society,

“The accretion process and the rotation of the black hole lead to the formation of relativistic jets, where the particles are accelerated and emit radiations up to a thousand trillion energies of visible light. The discovery of the link between these objects and cosmic rays could be the ‘Rosetta stone’ of astrophysics high energy”, revealed Andrea Tramacere, from the University of Geneva.

Scientists used neutrino data from the IceCube Neutrino Observatory in Antarctica and BZCat — one of the most accurate catalogs of blazars.

Using this data, they had to prove that the blazars whose directional positions coincided with those of the neutrinos were not there by chance.

So, developed software able to estimate how similar the distributions of these objects in the sky appear.

“After rolling the dice several times, we found that the random association could only exceed that of the real dice once in a million trials. This is strong evidence that our associations are correct”, underlines Tramacere.

Despite the results of the study, the research team considers that the number of findings in this initial sample is just the “tip of the iceberg”.

They collected “new observational evidence” thanks to their effort, which is a key component in creating more accurate models of astrophysical accelerators.

“What we have to do now is understand the main difference between objects that emit neutrinos and those that don’t. This will help us to understand to what extent the environment and the accelerator ‘talk’ to each other”, emphasizes the team.

“We will then be able to discard some models, improve the predictive power of others, and finally add more pieces to the eternal puzzle from the acceleration of cosmic rays,” the researchers concluded.