Scientists from the CNRS, a consortium of German universities, and the Max-Planck-Institut für Kernphysik at the H.E.S.S. observatory have identified electrons and positrons with the highest energies recorded on Earth. This discovery provides evidence of cosmic processes emitting unknown colossal amounts of energy. The findings will be published on November 18 in the journal Physical Review Letters.
The universe contains extreme environments, including supernova remnants and active galactic nuclei, capable of emitting charged particles and gamma rays with energies far exceeding those produced by nuclear fusion in stars. Gamma rays can reveal much about their sources due to their undisturbed travel through space. In contrast, charged particles, known as cosmic rays, face challenges as they are influenced by magnetic fields and lose energy during their journey, complicating the determination of their origins.
Detecting electrons and positrons with energies exceeding one teraelectronvolt (TeV) is particularly challenging. Space-based instruments have limited detection areas, while ground-based instruments, like the H.E.S.S. Observatory in Namibia, indirectly detect cosmic rays through atmospheric particle showers. The observatory employs five large telescopes to capture Cherenkov radiation from these showers.
In a decade-long analysis, H.E.S.S. scientists utilized advanced algorithms to extract cosmic-ray electrons from background noise, resulting in an unmatched dataset. This analysis revealed new information about cosmic-ray electrons, with measurements reaching up to 40 TeV. A notable finding was a sharp break in the energy distribution of these particles.
Kathrin Egberts from the University of Potsdam, a co-author of the study, stated, “This is an important result, as we can conclude that the measured cosmic-ray electrons most likely originate from very few sources within a few thousand light years of our solar system, a small distance compared to the size of our galaxy.”