Pierre Auger Observatory

Cosmic Rays

The Earth is exposed to a continuous flux of high energy particles, called cosmic rays. Sources of such ratiation are, among others, the sun (at low energies) and supernova remnants (at intermediate energy scales). With an abundance of about one particle per $\text{km}^2$ and year also extremely high energetic particles with energies beyond $10^{18}$ eV can be found among the cosmic rays. These are the most energetic particles that can be found in the Universe! Their origin still unknown: could they possibly be produced by supermassive black holes which can be found in the centers of active galaxies? Are they messengers of still unknown processes of new physics?

Extensive Air Showers

Because of their low flux, particles at the highest energies can only be measured indirectly through the particle cascades (extensive air showers) which they produce in the atmosphere. Within such an air shower, billions of secondary particles are produced propagating towards the ground where they can be detected with suitable devices

Pierre Auger Observatory

Our working group is a member of the Pierre Auger Collaboration Pierre Auger Collaboration. The Pierre Auger Observatory near the city of Malargüe, Argentina, is the worlds largest device for the measurement of these air showers. It covers an area of more than 3000 $\text{km}^2$ with about 1660 detector stations. In addition 27 fluorescence telescopes measure the fluorescence light, a faint afterglow in the air, induced by air showers. The Pierre Auger Observatory is an international large-scale project and is being operated by about 400 scientists from 18 different nations.

Fields of activity of the Siegen working group:

• Search for ultra-high-energy photons
• Multimessenger astronomy of astrophysical transient sources
• Mass composition of cosmic rays
• Studying possible deviations from Lorentz invariance using air showers