The Confinement Radius of a Cosmic Ray (Galactic vs. Extra-galactic)

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SUMMARY

The discussion focuses on determining the confinement of a cosmic ray particle within the Milky Way using the Larmor radius formula, r = γmc / qB. A specific example is provided with a 10^14 eV proton and a galactic magnetic field strength of 10^−11 T, illustrating that the particle remains confined within a radius of 15^15 kpc. Participants emphasize the importance of calculating the curvature radius to confirm confinement, noting that if the curvature radius is significantly smaller than the galaxy's radius, the particle will remain within the galaxy. Additionally, there is a mention of a potential error in the calculated radius of the Milky Way.

PREREQUISITES
  • Understanding of the Larmor radius in particle physics
  • Familiarity with relativistic mechanics
  • Knowledge of cosmic ray properties and behavior
  • Basic grasp of magnetic field effects on charged particles
NEXT STEPS
  • Explore the implications of magnetic fields on cosmic ray trajectories
  • Research relativistic particle dynamics and their applications
  • Learn about the structure and magnetic properties of the Milky Way
  • Investigate methods for calculating curvature radii in astrophysics
USEFUL FOR

Astronomers, astrophysicists, and students studying cosmic rays and galactic dynamics will benefit from this discussion.

mjda
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If we want to show whether or not a specific Cosmic Ray particle is confined to our galaxy we must use the Larmor radius (relativistic version),

r = γmc / qB

Considering a 10^14 eV proton and assuming the galactic magnetic field strength is 10^−11 T, show that the particle is confined to the Milky Way (radius 15^15 kpc).

How can we use the Larmor radius to prove that the particle is in fact confined to the Milky Way?
 
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Just plug in the values?
If the path of a particle has a curvature radius much smaller than the galaxy it won’t leave it, or at least will leave it only much later and severely scattered.

Something went wrong with the radius of the Milky Way.
 

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