Probing the spectral shape of dust emission with the DustPedia galaxy
  sample
  The objective of this paper is to understand the variance of the far-infrared
(FIR) spectral energy distribution (SED) of the DustPedia galaxies, and its
link with the stellar and dust properties. An interesting aspect of the dust
emission is the inferred FIR colours which could inform us about the dust
content of galaxies, and how it varies with the physical conditions within
galaxies. However, the inherent complexity of dust grains as well as the
variety of physical properties depending on dust, hinder our ability to utilise
their maximum potential. We use principal component analysis (PCA) to explore
new hidden correlations with many relevant physical properties such as the dust
luminosity, dust temperature, dust mass, bolometric luminosity, star-formation
rate (SFR), stellar mass, specific SFR, dust-to-stellar mass ratio, the
fraction of absorbed stellar luminosity by dust (f_abs), and metallicity. We
find that 95% of the variance in our sample can be described by two principal
components (PCs). The first component controls the wavelength of the peak of
the SED, while the second characterises the width. The physical quantities that
correlate better with the coefficients of the first two PCs, and thus control
the shape of the FIR SED are: the dust temperature, the dust luminosity, the
SFR, and f_abs. Finally, we find a weak tendency for low-metallicity galaxies
to have warmer and broader SEDs, while on the other hand high-metallicity
galaxies have FIR SEDs that are colder and narrower.
