Every second, a particle with the energy of a collider hits Earth
High-energy particles are constantly raining down on our planet, carrying the same punch as collisions in the Large Hadron Collider. While these cosmic rays are incredibly powerful, we have only recently begun to identify the massive celestial engines responsible for accelerating them.
Every single second, a particle with energy equivalent to a collision in the Large Hadron Collider (LHC) strikes every square kilometer of Earth [S1:p1]. These high-energy cosmic rays, primarily composed of protons, are vital to our Galaxy's energy budget [S2:p2]. For a long time, the exact origin of these rays remained a mystery, but evidence now points toward supernova remnants (SNRs) as the primary galactic factories [S1:p1, S2:p2].
The mechanism behind this acceleration is known as diffusive shock acceleration, or the first-order Fermi mechanism [S2:p2]. When a star explodes, the resulting shock waves act as natural particle accelerators [S2:p1]. In the remnant of the supernova observed in 1006 AD, known as SN 1006, scientists have detected X-ray synchrotron emission from ultrarelativistic electrons reaching energies of about 10 TeV [S2:<0xE2><0x80><0x8A>p3].
While the link between supernovas and cosmic rays is widely accepted, identifying them as the definitive source remains a complex challenge [S2:p4]. To prove SNRs are the main source, researchers must demonstrate they provide the necessary power—roughly 10^41 erg s^-1—to sustain Galactic cosmic rays [S2:p5]. Given that our Galaxy experiences about two supernovae per century, these remnants would need to convert 10–20% of their characteristic kinetic energy, approximately 10^51 erg, into cosmic rays [S2:p5].
Observing this process requires looking for specific signatures, such as gamma-ray emission. In SN 1006, both the HESS observatory and the Fermi telescope have detected gamma rays in the TeV and GeV bands [S2:p3, S1:p4]. However, debate continues over whether these rays come from electrons (the leptonic scenario) or from protons interacting with their environment (the hadronic origin) [S2:p4].
Source: How Supernovas Act as Universe’s Largest Particle Accelerators
