Sensitivity of the cherenkov telescope array to the detection of intergalactic magnetic fields

Manuel Meyer, Jan Conrad, Hugh Dickinson

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19 Scopus citations


Very high energy (VHE; energy E 100 GeV) γ-rays originating from extragalactic sources undergo pair production with low-energy photons of background radiation fields. These pairs can inverse-Compton-scatter background photons, initiating an electromagnetic cascade. The spatial and temporal structure of this secondary γ-ray signal is altered as the pairs are deflected in an intergalactic magnetic field (IGMF). We investigate how VHE observations with the future Cherenkov Telescope Array, with its high angular resolution and broad energy range, can potentially probe the IGMF. We identify promising sources and simulate γ-ray spectra over a wide range of values of the IGMF strength and coherence length using the publicly available ELMAG Monte Carlo code. Combining simulated observations in a joint likelihood approach, we find that current limits on the IGMF can be significantly improved. The projected sensitivity depends strongly on the time a source has been γ-ray active and on the emitted maximum γ-ray energy.

Original languageEnglish (US)
Article number147
JournalAstrophysical Journal
Issue number2
StatePublished - Aug 20 2016

Bibliographical note

Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved..


  • BL Lacertae objects: general
  • astroparticle physics
  • gamma rays: galaxies
  • magnetic fields


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