On May 18, 2023, the supernova named SN 2023ixf occurred about 22 million light-years away in Ursa Major, marking it as one of the brightest in proximity since the launch of Fermi.
Guillem Marti-Devesa from the University of Trieste noted, "Although supernovae are theorized to convert about 10% of their energy to accelerate cosmic rays, the recent data from SN 2023ixf suggest this might be as low as 1% shortly after the explosion."
The Earth's atmosphere is bombarded daily with cosmic rays, mainly composed of protons, with a minority of electrons and nuclei from heavier elements. These rays are deflected by magnetic fields due to their charge, making their paths untraceable.
Elizabeth Hays from NASA's Goddard Space Flight Center explained, "Cosmic rays produce gamma rays when interacting with matter. Given Fermi's sensitivity, its failure to detect these signals from SN 2023ixf challenges our understanding of cosmic ray origins."
Supernovae, which occur when a star more than eight times the mass of the Sun exhausts its fuel, are suspected major contributors to cosmic rays. These explosions send shock waves that accelerate particles, generating gamma rays upon colliding with surrounding matter and light.
Despite the role of supernovae in galactic dynamics and their potential in cosmic ray production, observations from SN 2023ixf have provided crucial insights. Matthieu Renaud of the National Center for Scientific Research in France stated, "The absence of gamma rays doesn't exclude the presence of cosmic rays, but it does necessitate a reevaluation of our assumptions about their acceleration and environmental impacts."
Fermi's observations after the explosion offer a foundational study of supernova conditions. Further research through additional spectral observations, new models, and future supernova studies are essential to demystify cosmic ray origins.
Research Report:Early-time gamma-ray constraints on cosmic-ray acceleration in the core-collapse SN 2023ixf with the Fermi Large Area Telescope
Related Links
Fermi Gamma-ray Space Telescope
Stellar Chemistry, The Universe And All Within It
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