Halpha imaging survey of Wolf-Rayet galaxies: morphologies and star
  formation rates
  The Halpha and optical broadband images of 25 nearby Wolf-Rayet (WR) galaxies
are presented. The WR galaxies are known to have the presence of a recent
($\le$10 Myr) and massive star formation episode. The photometric Halpha fluxes
are estimated, and corrected for extinction and line contamination in the
filter pass-bands. The star formation rates (SFRs) are estimated using Halpha
images and from the archival data in the far-ultraviolet (FUV), far-infrared
(FIR) and 1.4 GHz radio continuum wave-bands. A comparison of SFRs estimated
from different wavebands is made after including similar data available in
literature for other WR galaxies. The Halpha based SFRs are found to be tightly
correlated with SFRs estimated from the FUV data. The correlations also exist
with SFRs estimates based on the radio and FIR data. The WR galaxies also
follow the radio-FIR correlation known for normal star forming galaxies,
although it is seen here that majority of dwarf WR galaxies have radio
deficiency. An analysis using ratio of non-thermal to thermal radio continuum
and ratio of FUV to Halpha SFR indicates that WR galaxies have lesser
non-thermal radio emission compared to normal galaxies, most likely due to lack
of supernova from the very young star formation episode in the WR galaxies. The
morphologies of 16 galaxies in our sample are highly suggestive of an ongoing
tidal interaction or a past merger in these galaxies. This survey strengthens
the conclusions obtained from previous similar studies indicating the
importance of tidal interactions in triggering star-formation in WR galaxies.
