Speaker
Dr
Anita Reimer
(Institut für Theoretische Physik, Universität Innsbruck, Austria)
Description
The Fermi Large Area Telescope is scanning the sky for gamma-rays in the range ~20 MeV to over 300 GeV thereby revealing a wealth of high energy sources. Gamma rays may interact with low-energy photons from the Extragalactic Background Light (EBL) through photon-photon pair production if above the energy threshold. This results in redshift- and energy-dependent attenuation features in extragalactic source spectra such as from blazars and gamma-ray bursts (GRBs). Using photons above 10 GeV collected by the LAT during more than one year of observations from high-redshift blazars and GRBs, the effect of gamma-ray flux attenuation by the EBL is investigated. Several techniques are used to place robust upper limits on the gamma-ray opacity of the Universe at various energies and redshifts. By comparing with predictions from a range of EBL models, high-confidence limits on EBL intensity models at optical-ultraviolet wavelengths are derived.
Primary author
Dr
Anita Reimer
(Institut für Theoretische Physik, Universität Innsbruck, Austria)
