The source of the cosmic-ray excess in the Centaurus region -- constraints on possible candidates, mass composition and cosmic magnetic fields

Understand

The most significant excess in the arrival directions of ultra-high-energy cosmic rays with energies $\gtrsim40\,\mathrm{EeV}$ is found in the direction of several interesting source candidates, most prominently the nearby radio galaxy Centaurus A.

• Naturally, Cen A has been suspected to create the anisotropy - but very different scenarios have been proposed.
• This includes a subdominant source contribution in combination with isotropic background sources, as well as a scenario where Cen A supplies the whole cosmic-ray flux above the ankle.
• Recently, it was suggested that the overdensity could instead consist of strongly deflected events from the Sombrero galaxy.