Herschel-ATLAS: Revealing dust build-up and decline across gas, dust and
  stellar mass selected samples: I. Scaling relations
  We present a study of the dust, stars and atomic gas (HI) in an HI-selected
sample of local galaxies (z<0.035) in the Herschel Astrophysical Terahertz
Large Area Survey (H-ATLAS) fields. This HI-selected sample reveals a
population of very high gas fraction (>80 per cent), low stellar mass sources
that appear to be in the earliest stages of their evolution. We compare this
sample with dust and stellar mass selected samples to study the dust and gas
scaling relations over a wide range of gas fraction (proxy for evolutionary
state of a galaxy). The most robust scaling relations for gas and dust are
those linked to NUV-r (SSFR) and gas fraction, these do not depend on sample
selection or environment. At the highest gas fractions, our additional sample
shows the dust content is well below expectations from extrapolating scaling
relations for more evolved sources, and dust is not a good tracer of the gas
content. The specific dust mass for local galaxies peaks at a gas fraction of
~75 per cent. The atomic gas depletion time is also longer for high gas
fraction galaxies, opposite to the trend found for molecular gas depletion
timescale. We link this trend to the changing efficiency of conversion of HI to
H2 as galaxies increase in stellar mass surface density as they evolve.
Finally, we show that galaxies start out barely obscured and increase in
obscuration as they evolve, yet there is no clear and simple link between
obscuration and global galaxy properties.
