SCUBA observations of galaxies with metallicity measurements: a new method for determining the relation between submm luminosity and dust mass

Using a new technique we have determined a value for the constant of proportionality between submillimetre (submm) emission and dust mass, the dust mass absorption coefficient (κd) at 850μm. Our method has an advantage over previous methods in that we avoid assumptions about the properties of dust in the interstellar medium. Our only assumption is that the fraction of metals incorporated in the dust (ε) in galaxies is a universal constant. To implement our method we require objects that have submillimetre and far-infrared (FIR) flux measurements as well as gas mass and metallicity estimates. We present data for all the galaxies with suitable measurements, including new submm maps for five galaxies. We find κ850 = 0.07± 0.02m kg. We have also been able to use our sample to investigate our assumption that ε is a universal constant. We find no evidence that ε is different for dwarf and giant galaxies and show that the scatter in ε from galaxy to galaxy is apparently quite small.