Simulations of cosmic ray propagation

Area of Science:

• Astrophysics
• Computational Physics

Background:

• Cosmic rays (CRs) are high-energy particles propagating through astrophysical environments.
• Understanding CR propagation is key to galactic evolution and high-energy astrophysics.

Purpose of the Study:

• To review numerical methods for simulating CR propagation on galactic scales.
• To present algorithms for phenomenological and self-consistent CR propagation models.

Main Methods:

• Numerical solutions of the Fokker-Planck equation for kinetic CR description.
• Discretization and numerical solution of the CR transport equation coupled with MHD equations.
• Two-fluid approach and spectrally resolved particle evolution in physical and momentum space.

Main Results:

• Development of algorithms for phenomenological models with stationary interstellar medium.
• Development of algorithms for self-consistent models with dynamical coupling of CRs to thermal plasma.
• Incorporation of advection, diffusion, spallation, secondary production, and radiation mechanisms.

Conclusions:

• Numerical models are essential for interpreting CR data from various instruments.
• These models aid in understanding astrophysical processes like galactic winds and magnetic field amplification.
• Simulations provide insights into interstellar medium instabilities and galactic evolution.