ProFuse: Physical Multi-Band Structural Decomposition of Galaxies and
  the Mass-Size-Age Plane
  We present the new ProFuse R package, a simultaneous spectral (ultraviolet to
far infrared) and spatial structural decomposition tool that produces physical
models of galaxies and their components. This combines the functionality of the
recently released ProFound (for automatic source extraction), ProFit (for
extended source profiling) and ProSpect (for stellar population modelling)
software packages. The key novelty of ProFuse is that it generates images using
a self-consistent model for the star formation and metallicity history of the
bulge and disk separately, and uses target images across a range of wavelengths
to define the model likelihood and optimise our physical galaxy reconstruction.
The first part of the paper explores the ProFuse approach in detail, and
compares results to published structural and stellar population properties. The
latter part of the paper applies ProFuse to 6,664 z < 0.06 GAMA galaxies. Using
re-processed ugriZYJHKs imaging we extract structural and stellar population
properties for bulges and disks in parallel. As well as producing true stellar
mass based mass-size relationships, we further extend this correlation to
explore the third dimensions of age and gas phase metallicity. The disks in
particular demonstrate strong co-dependency between mass-size-age in a well
defined plane, where at a given disk stellar mass younger disks tend to be
larger. These findings are in broad agreement with work at higher redshift
suggesting disks that formed earlier are physically smaller.
