Montpellier, France – Scientists were surprised by the unexpected findings discovered during observations of the supernova SN 2023ixf in 2023. The event, located in the Pinwheel galaxy (Messier 101) about 22 million light-years away, provided a unique opportunity to study cosmic ray production. However, NASA’s Fermi Gamma-ray Space Telescope did not detect the high-energy gamma rays that were anticipated to be produced by these particles.
Previous estimates suggested that about 10% of a supernova’s total energy is converted into cosmic ray acceleration. Yet, the new observations of SN 2023ixf led to calculations revealing a much lower energy conversion rate of approximately 1% within days after the explosion. This unexpected result challenges prior assumptions about the role of supernovae in cosmic ray production, indicating that there is still much to learn about the process.
A paper led by Guillem Martí-Devesa, a researcher at the University of Trieste in Italy, sheds light on these findings. The study, conducted while Martí-Devesa was at the University of Innsbruck in Austria, will be published in a future edition of Astronomy and Astrophysics.
Cosmic rays, composed of hydrogen nuclei, electrons, and heavier elements’ nuclei, bombard Earth’s atmosphere daily. Despite extensive research into their origins since the early 1900s, tracing cosmic rays back to their sources remains a challenge due to their interaction with magnetic fields as they travel.
The absence of gamma rays detected by the Fermi Telescope following the SN 2023ixf explosion poses a mystery that astronomers are eager to solve. Understanding the relationship between cosmic rays and gamma rays is crucial in piecing together the puzzle of cosmic ray origins and acceleration mechanisms.
Supernovae, such as SN 2023ixf, have long been suspected of playing a significant role in cosmic ray acceleration. These massive explosions occur when a star runs out of fuel, leading to the acceleration of particles that create cosmic rays. The impact of supernovae on their galaxy’s interstellar environment can last for tens of thousands of years, influencing the evolution of galaxies.
Despite the challenges posed by the absence of gamma rays in the Fermi Telescope observations, researchers remain optimistic about future studies and simulations based on events like SN 2023ixf. Further investigations into young supernovae and collaborations across international institutions will continue to shed light on the enigmatic sources of cosmic rays in the universe.