A nearby supernova in 2023 offered astrophysicists an excellent opportunity to test ideas about how these types of explosions boost particles, called cosmic rays, to near light-speed. But surprisingly, NASA's Fermi Gamma-ray Space Telescope detected none of the high-energy gamma-ray light those particles should produce.
"Astrophysicists previously estimated that supernovae convert about 10% of their total energy into cosmic ray acceleration," said Guillem Martí-Devesa, a researcher at the University of Trieste in Italy."But we have never observed this process directly. With the new observations of SN 2023ixf, our calculations result in an energy conversion as low as 1% within a few days after the explosion.
Scientists have been investigating cosmic ray origins since the early 1900s, but the particles can't be traced back to their sources. Because they're electrically charged, cosmic rays change course as they travel to Earth thanks to magnetic fields they encounter. One theory proposes that supernovae may accelerate the most energetic cosmic rays in our galaxy in the first few days and weeks after the initial explosion.
"Unfortunately, seeing no gamma rays doesn't mean there are no cosmic rays," said co-author Matthieu Renaud, an astrophysicist at the Montpellier Universe and Particles Laboratory, part of the National Center for Scientific Research in France."We have to go through all the underlying hypotheses regarding acceleration mechanisms and environmental conditions in order to convert the absence of gamma rays into an upper limit for cosmic ray production.
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Fonte: physorg_com - 🏆 388. / 55 Consulte Mais informação »