Revealing The Ism Properties Of Star-Forming Dwarf Galaxies With CLOUDY

To understand how star-formation properties in galaxies evolve, a better characterization of their interstellar medium is needed. Thanks to Spitzer, Herschel, and now SOFIA, ALMA, we have detected for the first time in low-metallicity galaxies important cooling lines that provide great insight on the physical conditions of the ISM closely related to star formation. In this talk, I present our on-going work to model the multi-phase ISM of nearby low-metallicity star-forming galaxies using IR-mm observations and the spectral synthesis code CLOUDY. We find that the low-metallicity ISM differs dramatically from that of more metal-rich objects. It is characterized by harder radiation fields and a porous structure, with larger filling factors of ionized gas. The C+ emission arises mostly from photodissociation regions (PDRs), which have low covering factors and moderate UV fields. We also find that most of the molecular gas mass in those galaxies resides in PDRs not traced by CO.