Abstract We present O iii 88 μm observations towards four Herschel-selected dusty star-forming galaxies (DSFGs; log10μLIR/L⊙ = 13. 5 − 14 at z = 2. 9 − 4) using the Atacama Compact Array (ACA) in Bands 9 and 10. We detect O iii emission in all four targets at 3σ, finding line luminosity ratios (L ₎_₈₈₈ / L ₈ₑ = 10^-4. 2 to 10−3) similar to local spiral galaxies, and an order of magnitude lower when compared with local dwarf galaxies as well as high-redshift Lyman-break galaxies. Using the short-wavelength capabilities of the ACA, these observations bridge the populations of galaxies with O iii emission at low redshift from space missions and at high redshift from ground-based studies. The difference in O iii emission between these DSFGs and other high-redshift galaxies reflects their more evolved stellar populations (10 Myr), larger dust reservoirs (Mdust ∼ 109 − 11 M⊙), metal-rich interstellar medium (Z ∼ 0. 5 − 2 Z⊙), and likely weaker ionization radiation fields. Ancillary C ii emission on two targets provide LO\, III/LC\, II ratios at 0. 3 − 0. 9, suggesting that ionized gas represents a smaller fraction of the total gas reservoir in DSFGs, consistent with theoretical models of DSFGs as transitional systems between gas-rich, turbulent disks and more evolved, gas-poor galaxies. Expanding samples of DSFGs with O iii emission will be key to place this heterogeneous, poorly-understood galactic phase in its astrophysical context.
Bakx et al. (Thu,) studied this question.