Ultrahigh-energy cosmic rays dipole and beyond

Author(s)

Lang, Rodrigo Guedes ; Taylor, Andrew M. ; de Souza, Vitor

• Document type: Journal article
• Source: PHYSICAL REVIEW D; v. 103, n. 6, p. 12-pg., 2021-03-03.

Abstract

Recent data from the Pierre Auger Observatory has revealed the presence of a large-scale dipole in the arrival direction distribution of ultrahigh-energy cosmic rays (UHECR). In this work, we build up an understanding of the diffusive origin of such a dipolar behavior as well as its dependency on energy and astrophysical source assumptions such as extra-Galactic magnetic field strength and cosmic ray composition. We present a novel analytical approach for calculating the angular distribution of CR coming from a single source and discuss the regimes in which the steady-state dipole result is expected. We also present a semianalytical method for calculating the evolution with energy of the resultant dipole for an ensemble of sources. We show that a local source allows for a strong growth of the dipole with energy over a large energy range. The possibility of a transition from a dipolar to nondipolar regime at the highest energies and its implications for the source density, magnetic field intensity, and cosmic ray composition are discussed. (AU)

• FAPESP's process: 15/15897-1 - Cherenkov Telescope Array - CTA
• Grantee: Luiz Vitor de Souza Filho
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/24943-0 - New physics in astroparticle physics: dark matter and Lorentz invariance
• Grantee: Rodrigo Guedes Lang
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/01653-4 - On the importance of local sources of ultra-high energy cosmic rays
• Grantee: Rodrigo Guedes Lang
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate