Experimental Astroparticle Physics

The Research Group of Olaf Reimer is interested in sigantures of Cosmic Ray interactions. Particle decay and energy loss processes, acceleration and transport yield observable phenomenology at high energy gamma-rays. Experimental astroparticle physics investigates sources of CRs as well as interactions between primary particle and nuclei and their charged or neutral secondaries. We use data from space observatories or observations from ground-based telescope arrays.

Gamma-ray astrophysics using space telescopes focus on signatures of particle interactions in astrophysical environments and their interpretation. Data from the Fermi Gamma-ray Space Telescope are used to distinguish spectra, variability and periodicity pattern and allow us to assess source extension and morphology in a broad variety of astronomical objects. The Large Area Telescope measures photons between 30 MeV and 300 GeV and scans the full sky every 90 minutes. As member of the instrument team we investigate the still insufficiently understood binary systems, search for classes of astronomical gamma-ray emitters and study the dominant diffuse galactic gamma-ray emission.

Membership in one of the foremost capable experiments in ground-based gamma-ray astronomy, the High Energy Stereoscopic System (H.E.S.S.), allow us to extend observational coverage beyond the Fermi energy regime. This system of five imaging atmospheric Cherenkov telescopes was built at Khomas Highland, Namibia for the allowing prime access to the Galactic Center and excellent dark sky observation conditions. Gamma-ray astronomy at very high energies allows to resolve the expanding shock frontiers of Supernova remnants. The high instrumental sensitivity of the air Cherenkov technique allows measuring varying source extension as function of energy. As member of the collaboration we investigate particle acceleration at TeV-energies and characterize galactic gamma-ray sources according to their morphology, variability- and periodicity patters. Of particular interest is the transition regime from diffuse emission dominance at GeV energies to source dominance at TeV energies.

The future of gamma-ray astronomy will be defined by the Cherenkov Teleskope Array (CTA) presently under construction. Innsbruck University is shareholder in the observatory CTAO, the institute member of the consortium and actively involved in the preparation of future observations and the key science projects of the consortium. Furthermore, with MPIK Heidelberg, and the Universities of Erlangen and Tübingen we are involved in a consortium to construct new, fully-digital Cherenkov camera for the middle size telescope in CTA. A prototype is working since 2019 as principal camera on the large telescope CT5 in H.E.S.S. The observatory will be built on two locations at Paranal, Chile and La Palma, Spain and will preform a demanding and competitive observation program.

Gammamap of the sky, observed with the FERMI-Telescope


Head of the Research Group
Univ.-Prof. Dr. Olaf Reimer
Tel. +43 512 507-52060


Administrative Assistant
Claudia Wester
Tel. +43 512 507-52054

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