International School of Cosmic Ray Astrophysics <<Maurice M. Shapiro>>

21^st Course: Astroparticle Physics: Yesterday, Today, and Tomorrow
1-7 August, 2018

What began a few years ago with the detection of a few sources of high-energy gamma radiation has since developed into a rich field of research in high-energy astronomy. Gamma-ray photons carry crucial information about the most powerful processes in our universe. They allow the study of an impressive variety of non-thermal processes in a large number of astrophysical environments ranging from compact relativistic objects such as pulsars and accreting black holes to large scale cosmological structures such as galaxy clusters. After a short historical introduction, I will focus on the experimental challenges in the first lecture and discuss some results, especially with regard to the experimental limits of current experiments. In the second lecture, when other teachers of the school have laid the necessary theoretical foundations, I will discuss the state of the measurements, paying particular attention to the measurements of supernova remnants and the search for PeVatrons, the accelerators in our Milky Way that generate cosmic radiation up to energies of 10^15 eV. The lecture ends with an outlook at CTA, the Cherenkov Telescope Array, a global initiative to build an open observatory for ground-based gamma astronomy, which will be operational in the coming years.