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Filamentary diffusion of cosmic rays on small scales
G Giacinti1, M Kachelriess, D V Semikoz
1Institutt for fysikk, NTNU, Trondheim, Norway.
Physical Review Letters
|September 26, 2012
Summary
Cosmic rays diffuse anisotropically near sources in turbulent magnetic fields, creating irregular density structures. This anisotropic diffusion transitions to standard diffusion over time, impacting observable photon emissions.
Area of Science:
- Astrophysics
- Cosmic Ray Physics
- Plasma Physics
Background:
- Cosmic rays (CRs) are high-energy particles originating from astrophysical sources.
- Their propagation is crucial for understanding galactic and extragalactic phenomena.
- Turbulent magnetic fields are believed to play a significant role in CR diffusion.
Purpose of the Study:
- To investigate the diffusion of cosmic rays (CRs) in turbulent magnetic fields near their sources.
- To understand the resulting spatial distribution and structure of CRs.
- To determine the transition time from anisotropic to isotropic diffusion.
Main Methods:
- Simulating individual CR propagation in isotropic turbulent magnetic fields.
- Analyzing CR diffusion anisotropy at distances up to the maximum scale of magnetic field variations (lmax).
- Calculating photon emission from CR interactions with ambient gas.
Main Results:
- CRs exhibit anisotropic diffusion at distances r ≤ lmax from their sources.
- CR densities form irregular, filamentary structures around sources.
- A transition time (t*) to standard diffusion was determined, dependent on lmax, energy, and magnetic field strength.
Conclusions:
- Anisotropic diffusion near sources leads to observable irregularities in CR distribution and photon emission.
- The transition time to standard diffusion is a key parameter for understanding CR propagation.
- This study provides insights into the complex behavior of CRs in turbulent astrophysical environments.
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