Deep Near‐Infrared Mapping of Young and Old Stars in Blue Compact Dwarf Galaxies

We analyze J, H and Ks near-infrared data for 9 Blue Compact Dwarf (BCD)galaxies, selected from a larger sample that we have already studied in theoptical. We present contour maps, surface brightness and color profiles, aswell as color maps of the sample galaxies. The morphology of the BCDs in theNIR has been found to be basically the same as in the optical. The innerregions of these systems are dominated by the starburst component. At lowsurface brightness levels the emission is due to the underlying host galaxy;the latter is characterized by red, radially constant colors and isophotes wellfit by ellipses. We derive accurate optical near--infrared host galaxy colorsfor eight of the sample galaxies; these colors are typical of an evolvedstellar population. Interestingly, optical near--infrared color maps reveal thepresence of a complex, large-scale absorption pattern in three of the samplegalaxies. We study the applicability of the Sersic law to describe the surfacebrightness profiles of the underlying host galaxy, and find that, because ofthe limited surface brightness interval over which the fit can be made, thederived Sersic parameters are very sensitive to the selected radial intervaland to errors in the sky subtraction. Fitting an exponential model givesgenerally more stable results, and can provide a useful tool to quantify thestructural properties of the host galaxy and compare them with those of otherdwarf classes as well as with those of star-forming dwarfs at higher redshifts.Comment: 49 pages, 9 figures, 10 tables, accepted for publication in the Astrophysical Journa