Far-infrared properties of blue compact dwarf galaxies observed with AKARI/far-infrared surveyor (FIS)

Abstract

We report on the basic far-infrared (FIR) properties of eight blue compact dwarf galaxies (BCDs) observed by AKARI. We have measured the fluxes at the four FIS bands (wavelengths of 65 μm, 90 μm, 140 μm, and 160 μm). Based on these fluxes, we have estimated basic quantities of dust: dust temperature, dust mass, and total FIR luminosity. We find that the typical dust temperature of the BCD sample is systematically higher than that of normal spiral galaxies, although there is a large variety. The interstellar radiation field estimated from the dust temperature ranges up to 100-times the galactic value. This confirms the concentrated star-forming activity in BCDs. The starformation rate can be evaluated from the FIR luminosity as 0.01-0.5 M⊙ yr -1. Combining this quantity with the gas mass taken from the literature, we have estimated the gas consumption timescales (gas mass divided by the starformation rate), which have proved to span a wide range from 1 Gyr to 100 Gyr. A natural interpretation of this large variety can be provided by intermittent star-formation activity. We finally show the relation between dust-to-gas ratio and metallicity (we utilized our estimate of dust mass, and took other necessary quantities from the literature). There is a positive correlation between dust-to-gas ratio and metallicity, as expected from chemical evolution models. © 2008. Astronomical Society of Japan.