The ISM scaling relations in DustPedia late-type galaxies: A benchmark
  study for the Local Universe
  The purpose of this work is the characterization of the main scaling
relations between all the ISM components (dust, atomic/molecular/total gas),
gas-phase metallicity, and other galaxy properties, such as Mstar and galaxy
morphology, for late-type galaxies in the Local Universe. This study is
performed by extracting late-type galaxies from the entire DustPedia sample and
by exploiting the large and homogeneous dataset available thanks to the
DustPedia project. The sample consists of 436 galaxies with morphological stage
from T = 1 to 10, Mstar from 6 x 10^7 to 3 x 10^11 Msun, SFR from 6 x 10^(-4)
to 60 Msun/yr, and 12 + log(O/H) from 8 to 9.5. The scaling relations involving
the molecular gas are studied by assuming both a constant and a
metallicity-dependent XCO. The analysis has been performed by means of the
survival analysis technique. We confirm that the dust mass correlates very well
with the total gas mass, and find -- for the first time -- that the dust mass
correlates better with the atomic gas mass than the molecular one. We
characterize important mass ratios such as gas fraction, molecular-to-atomic
gas mass ratio, dust-to-total gas mass ratio (DGR), and dust-to-stellar mass
ratio. Only the assumption of a metallicity-dependent XCO reproduces the
expected decrease of the DGR with increasing morphological stage and decreasing
gas-phase metallicity, with a slope of about 1. DGR, gas-phase metallicity, and
the dust-to-stellar mass ratio are, for our galaxy sample, directly linked to
the galaxy morphology. The molecular-to-atomic gas mass ratio and the DGR show
a positive correlation for low molecular gas fractions, but for molecular gas
rich galaxies this trend breaks down. This trend has never been found
previously, to our knowledge. It provides new constraints for theoretical
models of galaxy evolution and a reference for high-redshift studies.
