Researchers at the High Energy Stereoscopic System (HESS) observatory in Namibia have reported detecting the most energetic cosmic ray electrons and positrons ever observed.
According to WP Tech, with energies exceeding 40 teraelectronvolts (TeV), these particles lose energy as they travel through space, indicating their source must be relatively close to Earth.
The universe is filled with powerful phenomena that produce highly energetic particles.
Supernova remnants, pulsars, and active galactic nuclei are known to emit charged particles and gamma rays with energy levels far beyond those generated by nuclear fusion in stars.
In a study published in Physical Review Letters, the HESS consortium describes the detection of these record-breaking cosmic rays. Due to their energy loss during interstellar travel, these particles are believed to originate from sources within a few thousand light-years of our Solar System—a small distance on a galactic scale.
Gamma rays, which travel unimpeded through space, provide clear insights into their origins.
In contrast, charged cosmic rays like electrons and positrons are influenced by magnetic fields throughout the universe, scattering them in all directions and complicating the identification of their source.
High-energy cosmic ray particles, particularly those exceeding 1 TeV, lose energy rapidly as they interact with light and magnetic fields. This makes their detection on Earth challenging and points to the likelihood of nearby particle accelerators capable of producing such powerful rays.
The HESS observatory specializes in capturing Cherenkov radiation—a faint light produced by highly charged particles and photons entering Earth’s atmosphere. Though its primary focus is studying gamma rays, HESS has enabled significant breakthroughs in cosmic ray detection.
Using four 12-meter telescopes, researchers analyzed a decade’s worth of data with cutting-edge algorithms designed to extract cosmic ray electrons from background noise.
This unique dataset allowed scientists to identify cosmic ray electrons with energies up to 40 TeV, revealing a distinct break in their energy distribution.
Clues to a Nearby Source
“This is an important result because we can conclude that the measured cosmic ray electrons most likely come from a small number of sources close to our Solar System, at a distance of up to a few thousand light-years,” said Kathrin Egberts of the University of Potsdam, one of the study's authors.
The findings suggest these particles were accelerated by nearby astrophysical phenomena, although the exact sources remain unknown.
