Informal Astro Talk
On ultra-high energy cosmic-ray origin
In the past few years new measurements (brought by experiments such as KASCADE-Grande, the Pierre Auger Observatory or Telescope Array) have radically improved our knowledge of the highest energy domain of the cosmic-ray spectrum. Recent Auger composition analyses suggest a composition getting gradually heavier above a few 10^18 eV. I will first review the recent observations (energy spectrum, composition and arrival directions). I will show that the observational data across the Galactic-to-extragalactic cosmic-ray transition can be described with minimal assumptions within a generic model putting together only one Galactic component and one extragalactic component. I will finally discuss multi-messenger constrains brought by neutrino and gamma-ray experiments.