A radio continuum and H I study of optically selected blue compact dwarf galaxies: Mrk 1039 and Mrk 0104

Abstract

We present a GMRT radio continuum and H I study of two Blue Compact Dwarf (BCD) galaxies Mrk 1039 and Mrk 0104. GMRT 610 MHz observations of Mrk 1039 show that the emission is coincident with a bright intense star forming region in the east of the galaxy. The emission at 610 MHz is more extended compared to higher frequencies. The radio spectrum is found to steepen away from the star forming region, suggesting the dominance of the non-thermal component at 610 MHz which maybe due to an older (few 100 Myr old) burst. We detect radio emission at 610 and 240 MHz from Mrk 0104 and estimate a spectral index of -1.14. We find that the emission is more extended at the low GMRT frequencies compared to the 1.4 GHz emission. The galaxy shows extended H I distribution which is about 1.3 times the optical size and contains a mass of 9×10^8 Mȯ. We also detect a H I cloud about ˜ 4.5 kpc to the north of the galaxy which does not have any obvious optical counterpart. We speculate that this H I cloud could be involved in triggering the current burst of star formation in Mrk 0104.