  The existence of intergalactic magnetic fields (IGMFs) is an open problem in
cosmology and has never been unambiguously confirmed. High-energy gamma rays
emitted by blazars are unique probes of cosmic magnetism, as their interactions
with pervasive radiation fields generate a short-lived charged component
sensitive to intervening magnetic fields. Spatial and temporal properties of
the secondary gamma rays generated in the electromagnetic cascade can provide
information about the strength, power spectrum, and topology of IGMFs. To probe
these fields, detailed simulations of gamma-ray propagation in the
intergalactic medium are necessary. In this work the effects of magnetic fields
on the spectrum and arrival directions of gamma rays are studied using
three-dimensional simulations, emphasising the particular case of helical
IGMFs.
