Small-scale Anisotropies of Cosmic Rays from Turbulent Flow

Abstract

Within the classical convection–diffusion approximation, we show that the angular distribution of cosmic rays (CRs) in a highly turbulent flow may exhibit significant small-scale anisotropies. The CR intensity angular power spectrum C _ℓ is then a direct reflection of interstellar turbulence, from which one expects C _ℓ ∝ ℓ ^− ^γ ^−1 for ℓ ≫ 1, where γ is the power-law turbulence spectral index. Observations by IceCube and HAWC at TeV energies can be explained approximately with the Kolmogorov law γ = 5/3 with a convection velocity dispersion of 20 km s ^−1 on the scale of 10 pc.

Keywords

• High energy astrophysics
• Particle astrophysics
• Cosmic rays
• Galactic cosmic rays
• Cosmic ray astronomy
• Interstellar medium