Where do cosmic rays come from?

Cosmic rays are high-speed particles, primarily atomic nuclei or electrons, that travel through space. Their origins are categorized based on their source and energy levels:1

• Galactic Cosmic Rays (GCRs): Most cosmic rays originate within the Milky Way Galaxy. It is widely accepted that a significant portion of these particles are accelerated by the expanding shock waves from supernova remnants, particularly those resulting from core-collapse supernovas.123
• Solar Cosmic Rays: Energetic particles also emerge from the Sun, specifically during solar flares and coronal mass ejections, where they are accelerated by strong magnetic fields.4
• Extragalactic Sources: Particles with the highest energies almost certainly originate from outside the Milky Way. While the exact mechanisms of all cosmic ray production remain a subject of study, active galactic nuclei—regions at the centers of galaxies powered by supermassive black holes—are known to emit high-speed particle jets and are considered significant sources of high-energy radiation.15