PeVatrons

Syllabus: General Studies Paper 3

A study using 12 years of data from NASA’s Fermi telescope helped scientists understand PeVatrons, or the source of a kind of extremely high-energy cosmic particles.

• NASA’s Fermi Gamma-ray Space Telescope, scientists are finally getting close to accurately identifying PeVatrons, the source of some of the highest energy particles that whip across our galaxy.
• Streams of particles called cosmic rays travel at breakneck speeds around our galaxy and they also strike our planet’s atmosphere. 
• They typically consist of protons but sometimes also include atomic nuclei and electrons. 
• They all carry an electric charge, this means that their paths deviate and scramble as they go through our galaxy’s magnetic field.
• This means that we can no longer tell which direction they originally came from, effectively masking their birthplace. 
• But when the particles that are part of cosmic rays collide with the gas near supernova remnants, they produce gamma rays; some of the highest-energy forms of radiation that exist.
• “Theorists think the highest-energy cosmic ray protons in the Milky Way reach a million billion electron volts, or PeV energies. The precise nature of their sources, which we call PeVatrons, has been difficult to pin down,” 
• These particles get trapped by the chaotic magnetic fields near supernova remnants. 
• They pass through the supernova’s shock wave multiple times and each time they do, they gain speed and energy. 
• Eventually, they can no longer be held by the supernova remnant and will careen off into deep space.
• These particles are boosted to 10 times the energy that the Large Hadron Collider, the most powerful man-made particle accelerator, can generate.