Blue compact dwarf galaxies with <i>Spitzer</i>: the infrared/radio properties

We study the correlation between the radio, mid-infrared, and far-infrared properties for a sample of 28 blue compact dwarf (BCD) and low-metallicity star-forming galaxies observed by Spitzer. We find that these sources extend the same far-infrared-to-radio correlation typical of star-forming late-type galaxies to lower luminosities. In BCDs, the 24 μm (or 22 μm) mid-infrared-to-radio correlation is similar to that of starburst galaxies, although there is somewhat larger dispersion in their q24 parameter compared to their qFIR. No strong correlations between the q parameter and galaxy metallicity or effective dust temperature have been detected, although there is a hint of decreasing q24 at low metallicities. The two lowest metallicity dwarfs in our sample, I Zw 18 and SBS 0335-052E, despite their similar chemical abundance, deviate from the average q24 ratio in opposite manners, displaying an apparent radio excess and dust excess, respectively