EGMF Constraints from Simultaneous GeV-TeV Observations of Blazars

摘要: Attenuation of the TeV gamma-ray flux from distant blazars through pair production with extragalactic background light leads to development electromagnetic cascades and subsequent, lower energy, GeV secondary emission. Due deflection VHE cascade electrons by magnetic fields (EGMF), spectral shape this arriving emission is dependent on strength EGMF. Thus, GeV-TeV has potential probe EGMF along line sight object. We investigate constraints derived observations for which simultaneous those Fermi telescope were reported. study dependence bound hidden assumptions it rests upon. select blazar objects Fermi/LAT Veritas, MAGIC or HESS have been published. model beams these sources using Monte Carlo simulations, including calculation temporal delay incurred photons, relative propagation time direct gamma-rays source. Constraints could be data RGB J0710+591, 1ES 0229+200, 1218+304. The measured source level in band than expected component calculated under assumption zero Assuming that reason suppression extended nature emission, we find B>10^{-15} G (assuming correlation length ~1 Mpc) consistent data. Alternatively, caused photons are B>10^{-17} same length.