Deep Radio Continuum Imaging of the Dwarf Irregular Galaxy IC10: Tracing
  Star Formation and Magnetic Fields
  We exploit the vastly increased sensitivity of the Expanded Very Large Array
(EVLA) to study the radio continuum and polarization properties of the
post-starburst, dwarf irregular galaxy IC10 at 6 cm, at a linear resolution of
~50 pc. We find close agreement between radio continuum and Halpha emission,
from the brightest HII regions to the weaker emission in the disk. A
quantitative analysis shows a strictly linear correlation, where the thermal
component contributes 50% to the total radio emission, the remainder being due
to a non-thermal component with a surprisingly steep radio spectral index of
between -0.7 and -1.0 suggesting substantial radiation losses of the cosmic-ray
electrons. We confirm and clearly resolve polarized emission at the 10-20%
level associated with a non-thermal superbubble, where the ordered magnetic
field is possibly enhanced due to the compression of the expanding bubble. A
fraction of the cosmic-ray electrons has likely escaped because the measured
radio emission is a factor of 3 lower than what is suggested by the Halpha
inferred SFR.
