The research in the field of Astroparticle Physics at KVI-CART focuses on the study of the sky map of the high-energy Universe, addressing the unknown origin of cosmic rays at the highest energies. Cosmic rays are a collective name for a variety of subatomic particles that are continuously bombarding the outer layers of the Earth’s atmosphere. While the Sun is a well-known source of low-energy cosmic rays, the origin of particles with energies in excess of 10¹² eV is still an open question. Supernovae explosions, for instance, are commonly believed to be the source of cosmic rays with energies up to 10¹⁵ eV, but so far it has not been possible to prove this observationally. Beyond this energy domain cosmic-ray particles must originate from unknown extragalactic sources at very large distances. Some of these particles are reaching energies well in excess of the highest energies that can be produced in the most advanced man-made particle accelerators. In fact, cosmic rays are the only observed ultra-high energy (UHE) particles on Earth, i.e. with energies in excess of 10¹⁶ eV. Still, the acceleration mechanism(s) leading to such ultra-high energies and their sources remain largely unknown.