They were known to be invisible and elusive, and we now know that the most elusive of all particles, the high-energy cosmic neutrinos, are also ubiquitous in the Milky Way. Seeing its glow across the galaxy is made possible by the massive amount of data collected over ten years by IceCube, the world’s largest neutrino telescope that studies these cosmic ghosts of Antarctic ice, at a base near the American Amundsen-Scott station, with thousands of sensors spread out. in cubic kilometres. He did this with the help of artificial intelligence, which obtained theoretical models based on a huge amount of data. The discovery, which opens a new chapter in high-energy astrophysics in the Milky Way, has been published in the journal Science by hundreds of researchers from the IceCube International Collaboration, which includes 58 institutions from 14 countries including the University of Padua. Italy, together with Infn, made an important contribution with theoretical models. The Universities of Pisa, Federico II of Naples, Sapienza University of Rome, Gran Sasso Institute of Science and Stockholm University also contributed to its development. The discovery confirms a phenomenon expected decades ago, which is the presence of a halo spreading in our galaxy consisting of cosmic neutrinos, which are particles that pass continuously through matter, from Earth to the human body, without leaving any traces. It’s a discovery that “definitely upends our understanding of both the distribution of matter in our galaxy and that of potential astrophysical sources of cosmic rays, because the detected signal is much more intense than various theoretical predictions,” Elisa told ANSA. from the University of Padua and coordinator of the Italian participation in IceCube. “This is the first time that a measurement of this type has been done, and it is much more difficult than those done so far because we are not looking for point sources, but rather a diffuse background,” notes Infn’s Dario Grasso, who collaborated with IceCube on the data analysis. . He adds that this analysis required “an additional step in statistical analysis and the use of artificial intelligence techniques.” The theoretical model obtained in this way made it possible to confirm the existence of a diffuse halo of high-energy neutrinos in the Milky Way. “There was a diffuse emission that wasn’t unexpected, and the new fact is that the emission was much more intense than expected,” he adds. “The Italian group presented the IceCube collaboration with a map related to the model, which made the analysis possible” In this way it turned out that “the traditional models have a mistake: there must be something different in the cosmic rays that collide with interstellar stars. The average production of more neutrinos, it is like If only they were more concentrated in the center of the galaxy.” In 2013, IceCube discovered very high-energy astrophysical neutrinos, inaugurated the so-called neutrino astronomy, and in 2018 announced the identification of the first extragalactic source, but so far the origin of most of the detected neutrinos is still unknown. The new discovery confirms the existence of more widespread and abundant neutrino emission than expected, as well as the presence of a group of cosmic rays in the deeper regions of the galactic plane, more energetic than those observed near Earth. This is valuable information for understanding the hitherto mysterious origin of cosmic rays. For Bernardini, “The next challenge will be to distinguish the diffuse signal of neutrinos due to the interactions of cosmic rays on their journey through the distributed matter in the galaxy, from that caused by neutrinos produced directly by astrophysical sources, which we are at the moment unable to distinguish yet. We We are looking for the origin of cosmic rays with completely new eyes.”
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