  A dynamical model including ram pressure stripping is applied to the strongly
HI deficient Virgo spiral galaxy NGC 4522. A carefully chosen model snapshot is
compared with existing VLA HI observations. The model successfully reproduces
the large-scale gas distribution and the velocity field. However it fails to
reproduce the large observed HI linewidths in the extraplanar component, for
which we give possible explanations. In a second step, we solve the induction
equation on the velocity fields of the dynamical model and calculate the large
scale magnetic field. Assuming a Gaussian distribution of relativistic
electrons we obtain the distribution of polarized radio continuum emission
which is also compared with our VLA observations at 6 cm. The observed maximum
of the polarized radio continuum emission is successfully reproduced. Our model
suggests that the ram pressure maximum occurred only ~50 Myr ago. Since NGC
4522 is located far away from the cluster center (~1 Mpc) where the
intracluster medium density is too low to cause the observed stripping if the
intracluster medium is static and smooth, two scenarios are envisaged: (i) the
galaxy moves very rapidly within the intracluster medium and is not even bound
to the cluster; in this case the galaxy has just passed the region of highest
intracluster medium density; (ii) the intracluster medium is not static but
moving due to the infall of the M49 group of galaxies. In this case the galaxy
has just passed the region of highest intracluster medium velocity. This study
shows the strength of combining high resolution HI and polarized radio
continuum emission with detailed numerical modeling of the evolution of the gas
and the large-scale magnetic field.
