GMRT radio continuum study of Wolf Rayet galaxies I: NGC 4214 and NGC
  4449
  We report low frequency observations of Wolf-Rayet galaxies, NGC 4214 and NGC
4449 at 610, 325 and 150 MHz, using the Giant Meterwave Radio Telescope (GMRT).
We detect diffuse extended emission from NGC 4214 at and NGC 4449. NGC 4449 is
observed to be five times more radio luminous than NGC 4214, indicating
vigorous star formation. We estimate synchrotron spectral index after
separating the thermal free-free emission and obtain $\alpha_{nt}=-0.63\pm0.04$
(S$\propto\nu^{\alpha_{nt}}$) for NGC 4214 and $-0.49\pm0.02$ for NGC 4449.
About $22\%$ of the total radio emission from NGC 4214 and $\sim 9\%$ from NGC
4449 at 610 MHz is thermal in origin. We also study the spectra of two compact
star-forming regions in NGC 4214 from 325 MHz to 15 GHz and obtain
$\alpha_{nt}=-0.32\pm0.02$ for NGC 4214-I and $\alpha_{nt}=-0.94\pm0.12$ for
NGC 4214-II. The luminosities of these star-forming regions ($\sim 10^{19}\rm
W~ Hz^{-1}$) appear to be similar to those in circumnuclear rings in normal
disk galaxies observed with similar linear resolution. We detect the supernova
remnant SNR J1228+441 in NGC 4449 and estimate the spectral index of the
emission between 325 and 610 MHz to be $-1.8$ in the epoch 2008-2009. The
galaxies follow the radio-FIR correlation slopes suggesting that star formation
in Wolf - Rayet galaxies, which are low-metallicity systems, are similar to
that of normal disk galaxies.
