ASTRONOMY COLLOQUIUM

The earth has been bombarded by high-energy particles for millions of years. Known as cosmic rays, these particles can have higher energies than particles accelerated by the best human-made accelerators. Since the discovery of cosmic rays in 1912, we have studied these energetic particles for over a hundred years. These particles should be accelerated under a more extreme environment than our Sun to obtain their high energies. Supernova remnants have been the most supported candidates to be our Galaxy's main sources of cosmic rays. However, it is challenging to study the sources of these particles because of the deflection of their trajectories by magnetic fields and their interactions with particles and radiation in interstellar and intergalactic space. Observations of the neutral particles, such as gamma rays and neutrinos, produced during the interactions experienced by cosmic rays have been expected to provide the key measurements to find the elusive source sites of cosmic rays. In recent decades, we have seen great improvements in cosmic-ray and gamma-ray measurements. High-energy gamma-ray observations have discovered over 200 astrophysical objects emitting gamma rays with energies higher than 100 GeV, while cosmic-ray measurements have revealed many unexpected features in the spectrum and composition. I will present an overview of current high-energy cosmic-ray and gamma-ray observations of our Galaxy, and a glimpse into future perspectives.

To view this talk on YouTube, please visit: https://www.youtube.com/playlist?list=PLb1880Rn0qkKFkWyROUq1kRlgCsuBTrnd