Deciphering the Dipole Anisotropy of Galactic Cosmic Rays

Area of Science:

• Astrophysics
• Particle Physics
• Cosmic Ray Physics

Background:

• Recent measurements reveal significant energy dependence in the dipole anisotropy of Galactic cosmic rays (CRs) across the TeV-PeV energy range.
• Understanding the origins and propagation of high-energy CRs is crucial for astrophysics and particle physics.

Purpose of the Study:

• To explain the observed energy-dependent dipole anisotropy in Galactic cosmic rays.
• To identify potential local sources contributing to this anisotropy.
• To validate standard diffusion theory in the context of CR propagation.

Main Methods:

• Analysis of recent measurements of CR arrival directions.
• Application of standard diffusion theory incorporating multiple factors.
• Modeling the influence of local sources, magnetic fields, and solar system motion.

Main Results:

• The observed dipole anisotropy is well-explained by a combination of factors within standard diffusion theory.
• Local sources, particularly in the Galactic longitude range 120°≲l≲300°, dominate the CR gradient below 0.1-0.3 PeV.
• The Vela supernova remnant is identified as a strong candidate for the local CR source responsible for the 1-100 TeV dipole anisotropy.

Conclusions:

• The energy-dependent dipole anisotropy of Galactic cosmic rays is a natural consequence of diffusion theory.
• Local astrophysical environments, including supernova remnants and magnetic fields, significantly influence observed CR characteristics.
• The findings support the role of the Vela supernova remnant as a nearby source of high-energy cosmic rays.