Dust-to-gas ratio and star formation history of blue compact dwarf galaxies

Abstract

This paper investigates the origin of the observed large variety in dust-to-gas ratio among blue compact dwarf galaxies (BCDs). By applying our chemical evolution model, we find that the dust destruction can largely suppress the dust-to-gas ratio when the metallicity of a BCD reaches $12+\log{\rm (O/H)}\sim 8$, i.e., a typical metallicity level of BCDs. We also show that dust-to-gas ratio is largely varied owing to the change of dust destruction efficiency that has two effects: (i) a significant contribution of Type Ia supernovae to total supernova rate; (ii) variation of gas mass contained in a star-forming region. While mass loss from BCDs was previously thought to be the major cause for the variance of dust-to-gas ratio, we suggest that the other two effects are also important. We finally discuss the intermittent star formation history, which naturally explains the large dispersion of dust-to-gas ratio among BCDs.