Polarisation of Radio Relics in Galaxy Clusters
  Radio emission in the form of giant radio relics is observed at the periphery
of galaxy clusters. This non-thermal emission is an important tracer for
cosmic-ray electrons and intracluster magnetic fields. One striking
observational feature of these objects is their high degree of polarisation
which provides information on the magnetic fields at the relics' positions. In
this contribution, we test if state-of-the-art high resolution cosmological
simulations are able to reproduce the polarisation features of radio relics.
Therefore, we present a new analysis of high-resolution cosmological
simulations to study the polarisation properties of radio relics in detail. In
order to compare our results with current and future radio observations, we
create mock radio observations of the diffuse polarised emission from a massive
galaxy clusters using six different projections, for different observing
frequencies and for different telescopes. Our simulations suggest that, due to
the effect of Faraday rotation, it is extremely difficult to relate the
morphology of the polarised emission for observing frequencies below $1.4 \
\mathrm{GHz}$ to the real magnetic field structure in relics. We can reproduce
the observed degree of polarisation and also several small-scale structures
observed in real radio relics, but further work would be needed to reproduce
some large-scale spectacular features as observed in real radio relics, such as
the "Sausage" and the "Toothbrush" relics.
