The cold gas and dust properties of red star-forming galaxies

Abstract

We study the cold gas and dust properties for a sample of red star-forming galaxies called 'red misfits.' We collect single-dish CO observations and H i observations from representative samples of low-redshift galaxies, as well as our own James Clerk Maxwell Telescope CO observations of red misfits. We also obtain SCUBA-2 850 $\mu$m observations for a subset of these galaxies. With these data we compare the molecular gas, total cold gas, and dust properties of red misfits against those of their blue counterparts ('blue actives') taking non-detections into account using a survival analysis technique. We compare these properties at fixed position in the log SFR-log M⋆ plane, as well as versus offset from the star-forming main sequence. Compared to blue actives, red misfits have slightly longer molecular gas depletion times, similar total gas depletion times, significantly lower molecular- and total-gas mass fractions, lower dust-to-stellar mass ratios, similar dust-to-gas ratios, and a significantly flatter slope in the log Mmol-log M⋆ plane. Our results suggest that red misfits as a population are likely quenching due to a shortage in gas supply.