(abridged) We present a study on the effects of the intracluster medium (ICM)
on the interstellar medium (ISM) of 10 Virgo cluster spiral galaxies using {\it
Spitzer} far-infrared (FIR) and VLA radio continuum imaging. Relying on the
FIR-radio correlation within normal galaxies, we use our infrared data to
create model radio maps which we compare to the observed radio images. For 6 of
our sample galaxies we find regions along their outer edges that are highly
deficient in the radio compared with our models. We believe these observations
are the signatures of ICM ram pressure. For NGC 4522 we find the radio deficit
region to lie just exterior to a region of high radio polarization and flat
radio spectral index, although the total 20 cm radio continuum in this region
does not appear strongly enhanced. These characteristics seem consistent for
other galaxies with radio polarization data in the literature. The strength of
the radio deficit is inversely correlated with the time since peak pressure as
inferred from stellar population studies and gas stripping simulations,
suggesting the strength of the radio deficit is good indicator of the strength
of the current ram pressure. We also find that galaxies having {\it local}
radio {\it deficits} appear to have {\it enhanced global} radio fluxes. Our
preferred physical picture is that the observed radio deficit regions arise
from the ICM wind sweeping away cosmic-ray (CR) electrons and the associated
magnetic field, thereby creating synchrotron tails as observed for some of our
galaxies. We propose that CR particles are also re-accelerated by ICM-driven
shocklets behind the observed radio deficit regions which in turn enhances the
remaining radio disk brightness.Comment: 19 pages, 10 figures; Astrophysical Journa
